Is This Mistake RUINING Your Acoustics? (and How to INSTANTLY Fix It)

[@warpacademy]

I wanted to pin a comment to the top here to address the most common question that's been coming up in the comments. That's, "You can't use EQ to correct the frequency response when you have SBIR because you'd just be boosting the drive signal and still causing destructive interference at the same frequency based on the 1/4 wavelength" or something to that effect. The answer is.....YES, you absolutely can. Using standard analog EQ, it's not possible. But when you employ digital adaptive EQ that uses a modelling delay, you can achieve a near perfect response correction. Here are the details on that, and my sources. I had thought the Sonarworks SoundID Reference platform was using this technology, but I was incorrect. I apologize. Sonarworks cannot correct phase distortion from boundaries, yet, although they tell me they're working on it and hope to deploy this in a future version. Take a look at the Journal of the Audio Engineering Society / JAES Volume 33 Issue 3 pp. 127-132; March 1985. Spectral, Phase, and Transient Equalization for Audio Systems, P. M. CLARKSON, J. MOURJOPOULOS, AND J. K. HAMMOND, Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton, UK. www.aes.org/e-lib/browse.cfm?elib=4461 If you want to see evidence of this technology that is currently available as a commercial product, look at the Trinnov system. In their technical literature, you'll find confirmation, complete with visual graphics, of how this technology works to correct phase distortion by using a modelling delay to time-align specific frequencies, thus correcting for phase shifts in a non-minimum phase or mixed phase system. www.trinnov.com/en/technologies/. Also the AES book Recording Studio Design by Philip Newell, page 332-334, which states "Near perfect response at optimum listening position after correction (with digital adaptive EQ)". This example was based on a test where a loudspeaker was positioned on a stand, part way through a room (exactly as I did in position 2 and 3), after which digital adaptive EQ was applied. This section of the book is also key to understanding why and how the correction can occur: "A non-minimum phase effect (such as when a loudspeaker is freestanding in a room, and not mounted at or in the wall) cannot be universally corrected by (analog) equalization (alone) of the loudspeaker drive signal. Even perfect amplitude correction could not restore the original phase response by any known practical analogue means. Only by digital signal processing could an almost perfect response be restored. Adaptive digital filtering can model, very accurately, the inverse phase responses necessary to correct either the minimum phase or non-minimum phase components of a transient or steady state response anomaly. By means of measuring microphones, modelling delays, and adaptive filtering processes, the digital systems can be made to 'learn' what a given room will do to a loudspeaker response, and apply acausal corrections to cancel the disturbances [acausal, in this sense, means that by means of a signal delay, the measured response error is fed into the drive-signal, in inverted form, to precondition the output to anticipate the error." -Pg 334, 11.5.2 Digital Correction Techniques, Recording Studio Design, Philip Newell, Audio Engineering Society. I followed up by speaking with Philip Newell directly on this matter. He personally watched this video, reviewed the comments, and confirmed this is a correct presentation of the information. Here are his comments on this specific topic: "I stand by what I said in the section that you quoted from Recording Studio Design, but it has to be taken in context. Acausal filtering and signal processing, WITH A MODELLING DELAY, can correct for the room boundary effects, but only for a very small region of a room -- say a very restricted 'sweet spot'. Elsewhere in the room, the response may then be much worse than before the correction. So, for example, if someone must work in an acoustically-poor room, this type of processing could greatly improve things at a restricted listening position, which may be beneficial to a single user, or it may 'somewhat' improve things over a slightly wider area, but it cannot make an overall improvement to the room acoustics. When one place is improved, another place will suffer." Furthermore, I spoke with the team at Sonarworks about their platform and this is what they've said on the topic: "We align the time between channels by phase measurements currently. The boundary nulling question: It will not be the same as it will still be there, but at a lower energy level. In short, phase-induced dips cannot be corrected by amplitude EQ only, only their impact lessened. For proper handling of phase effects, phase shaping is required." This parallels exactly what Philip Newell has stated. Sonarworks does not currently do phase shaping (I got this wrong, so sorry about that. I had thought their platform was doing this but I was incorrect.), but I hear they may be planning to roll this out in a future release. Also, to be clear, the audience for this is music studios, not audiophile hifi systems. In audio engineering control rooms, the flattest response possible is most certainly a primary goal. My comments to audiophiles are: Do what sounds good to you. You're the end user of your media and you should optimize it however you want to. Audio engineers and music producers, like myself, and many of the subscribers on my channel, have a different set of needs, which include accuracy and translation. Cheers!

[@keywestjimmy]

As a recovering audiophile and budding mix engineer, there are things both can learn from one another. Go to an audio show and listen to the top 3 rigs, you'll understand "audiophile sound character." In this priority: It's a recessed soundstage with 1) emphasis on depth and 2) solidity of apparent sounding body and 3) frequency accuracy. Engineers hear frequency accuracy 1st. Sounding body floats close to the listener, mostly L-R-C, intimately 2nd and 3rd low end punch is controlled, but not excessively tactile. Overall, engineers prefer a 3D soundstage close with forward reverberation and audiophiles prefer a 3D soundstage gigantic and recessed back and away. These are 2 unique sonic perspectives, achieved in slightly different ways and here's the crazy part: with the same source material. In other words, go ahead and mix for near-field, studio monitoring, but don't be surprised to hear this legitimately interpreted differently in a living-room with real-world room conditions. Peace.

[@warpacademy]

Hey hey. Interesting insights. For engineers, accuracy and translation are paramount, not just frequency response. Accuracy is more all encompassing (such as accurate transient response). Translation, as I'm sure you're aware, is ensuring that your engineering decisions still sound correct when monitored in many other listening environments & playback systems. This has been a much studied subject in audio engineering journals and acoustics research. Many (most?) audiophile listening environments do virtually nothing about 2 of the main obstacles to accuracy and hence the ability to translate: 1) Room reflections color the sound of the room - speaker system as much as (or sometimes more than) the speakers themselves. And because room reflections are unique only to that specific acoustic space, then any system that has much in the way of reflections has a pattern of constructive and destructive interference in the room and resonances that will dramatically skew the sound from anything resembling accurate. IE the music will sound wildly different from room to room. If there is some reflected energy in a control room, it will be scattered by the use of diffusors so the energy is dispersed in a hemi-disc (typically) rather than a hard, distinct, specular reflection. 2) Decay time. Most residential (and audiophile) listening environments have decays times (varying by frequency) of 500-1000 ms. This has a significant masking effect as the decaying frequencies obscure the perception of the next transient, or word in a vocal, or note in a melody. Long decays times are generally desirable in large chambers / theatres and halls of worship as they add a sense of lushness, but never for engineering purposes. Over the last 4 decades, the effect of decay times have been studied. Even decay times of 300-700 ms, which were common for old style control rooms, have now been proven inadequately long. Audiophile spaces have a completely different set of priorities, which is why I carefully set the context of this video before discussing the acoustics. Control rooms are not designed for enjoyable listening; they're designed to turn out mixes and masters that translate well, and to do that as quickly and efficiently as possible.

[@pen5139]

Nice video and explaination. Could Dirac solve this problem?

[@warpacademy]

Hey hey. AFAIK, no commercially available system (Trinnov, Dirac, Sonarworks) can correct boundary nulling. Theoretically it is possible by using a phase modelling delay / non-causal filter system, but nothing like that has been commercialized. It's only ever been demonstrated in a research setting by ISVR.

[@_OHEN]

This, was info was not only the correct information that I’ve been searching for, but very well organized. I can’t emphasize the value of references regarding these topics . Very well done, cheers .

[@dronbana]

You helped me solve 2 of my room’s biggest problems, 35hz and 80 hz. Thank you for this video 🙏🏼

[@warpacademy]

Glad I could help!

[@EverFroz3n]

So much valuable information! Thanks a lot for sharing. I can confirm all your test as I have both a Treated Mixing Studio and a Home Studio both calibrated with Sonarworx and I did get these curves as I tested different speaker positions. You put years of test in such a clear and concise video. Wonderfull work.

[@warpacademy]

Thanks for the comment. And I'm glad you've been able to optimize things in your studios using these principles. Cheers!

[@HumeAudio]

I've been sharing these videos with my clients, students and discord. Thanks for another fantastic video, you really go above and beyond on everything you do.

[@warpacademy]

Thanks for sharing these around. Much appreciated! All the best.

[@FOH3663]

You're absolutely right, flush mounted or inside of two feet. It's worth noting doing so elevates the importance of rear wall treatment, ie., all modes additively sum up and at a pressure maximum. Obviously you're on your of it with three feet of fluffy or whatever.

[@warpacademy]

Hey mate. Thanks for the comment. Yes, that font back axial room mode is down around 35 hz with our room dims. So the depth of treatment we have is absolutely necessary to reign in that mode.

[@sansproductionlounge8083]

Oh my goodness!!! This is an amazing video! Holy crap! I’m amazed with this experiment you have done. Keeping your speakers closer to the wall was actually insane! I cannot believe it. This video combined with your other one you did for Sonarworks is an incredible combination of knowledge. You are actually a wizard. Thank you for this absolute gold!

[@warpacademy]

Thank you so much! Glad you’ve gotten a lot of value out of these videos :)

[@VarunPratapSingh]

I watch every video from warp academy even tho I have an untreated room with the mackie CR4 :p waiting for your studio build update as well!

[@warpacademy]

Glad to have you on the channel! Happy music making.

[@trevorbartram5473]

I hope your viewers understand that this is studio specific guidance where flat frequency response is paramount. The requirements for Hi-Fi are different in that frequency response and sound staging must strike a balance. The best stereo sound staging produces aural images in front of, above, behind and to the far left & right of the speakers. I believe that is difficult to achieve in-wall or against a wall (except the Dutch & Dutch specialized speakers?). In Hi-Fi, sound staging is the reason why it is recommended that speakers be brought out into a room. A balance can only be achieved by listening to both sound staging and lack of bass room modes (not only rear wall but uncarpeted floor, ceiling and side walls too) and experimenting with various locations. I've just been thru this and it has taken many attempts and much listening to strike a happy balance.

[@warpacademy]

Hey hey. Thanks for the comment. Our audience on the channel here is definitely music producers and engineers. We've been publishing videos for that audience for over 10 years now. We're not talking about hi-fi, but perhaps it would be good for me to specifically state that in the intro. I figured that the fact I'm in a control room would make it obvious but it's always good to be crystal clear. Thanks for the feedback. Your comments on sound staging are interesting. I assume to a large part you're talking about stereo imaging? If so, there are substantial advantages with stereo field perception with a flush mounted speaker setup. Most notably, you eliminate cabinet edge diffraction which smears stereo imaging. With speakers on stands, you get edge diffraction, but that's eliminated by the front wall flush mount, which acts as a huge continuous baffle. Then you get further improvements in stereo field by eliminating much of the side wall reflections through the use of acoustic treatment on those boundaries. Side wall reflections from untreated surfaces smear transients and stereo field quite a bit. In home listening environments, such as typical living rooms, they're mayhem for acoustics. There's usually no symmetry, there's tons of diffraction sources, usually little or no acoustic treatment. I imagine it's a tall order to get accurate sound in that type of environment. But then again, perhaps that's not the goal as it is in a control room. Thanks for watching and commenting. All the best!

[@nicassiuscordero7173]

When we design churches, auditoriums, anechoic chambers, etc;.we try to find aesthetic acoustical solutions that blend and solve acoustic aberrations. A cnc perforated marble or hardwood could retain the finish the client wants, while maximizing the potential of the audiophile's speakers.

[@warpacademy]

Thanks for joining in the conversation. Are you working in the industry as a studio builder or acoustic consultant? Cheers!

[@nicassiuscordero7173]

@@warpacademy We can provide consultation services but most of our projects are design and build. The seamless integration of multiple disciplines is required to make a project exceptional since the ideal location for lighting, HVAC and ceiling speakers are always in the same spot. Being in control of the project gives us a balance between all the elements of a build, especially when value engineering is required to complete a project or make a project viable.

[@warpacademy]

Right on. Thanks for sharing a bit about your background. This is the room we're building at the moment: kzbin.info/www/bejne/a4fVeGWBlKpqp6s

[@Underview]

Another heavy hitter of a video! One thing to consider with the boosted lows in a situation with monitors flush against a wall is that it's actually preferable to flat when mixing low, and is just more fun in general to mix that way as opposed to flat.

[@warpacademy]

Thanks for the comment. You’re totally right. When mixing at low volumes the bass will be perceived as quieter due to equal loudness contours. So that would help avoid over mixing the bass. Good point!

[@Audfile]

Yeah, but up against the wall sounds gross everywhere else. You need bass, get some subs. I'm always near field or way out from the wall, via experience. Even my subs are away from the walls and lifted 3 feet off the ground.

[@warpacademy]

To be clear, we're talking about music studio control rooms here. Not audiophile hifi systems. It's an industry-wide best practice to flush mount monitors in control rooms for a multitude of reasons, and barring that, to put the monitors right up against the wall. If you're optimizing in an environment that's not a studio control room for engineering, then just do what sounds best to you. Cheers!

[@dilbydj]

​@@Audfilethere is only a single position that matters in a studio and that is your listing position. If it sounds good in the listening position and terrible everywhere else you are winning 🎉

[@warpacademy]

Well said. We generally optimize for the listening position. In my room - and many professional rooms - we needed a wider view though. You need to account for the fact that you'll also have clients and students in the room alongside you; not just a single engineer. In my room (it's a teaching studio where I sometimes have up to 8 additional people) it's a goal to have the frequency response as good as possible throughout a larger area. Of course it can't sound good everywhere, but by eventually flush mounting the monitors into the front wall (we're doing that right now) you can achieve that because it's minimum phase and no digital adaptive EQ correction is required. We can account for the LF lift (baffle step) by shelving down the monitor drive signal using analog EQ on the back of the KH420s and this will improve the response in all positions of the room. In most home and project studios though, you only need to have 1 area sound good. The mix position like you said. Thanks for watching and commenting!

[@fantasyflare]

Wow amazed by the quality of your videos. You're like the Dr. Berg of audio engineering.

[@warpacademy]

Thanks very much. Glad you've been enjoying them.

[@astrarivm]

Thank you, sir! So it's better to keep speakers closer to a wall with absorbers around than to have thick absorbers behind speakers and further from a wall?

[@warpacademy]

Yes, correct. Absorbers behind the speakers will not do much for the sub range under 100 hz. Porous absorption performs very poorly there and it also performs more poorly when particle velocity is zero which is exactly what it’s at when you reach a boundary (wall).

[@DaftFader]

Thanks for this video. I always used to have my speakers up against the wall, but for some reason, on Adam's instruction manual they say to put the speakers 30cm away from the wall ... So I did with my new Adams, and I get the exact dips and boosts you show in the vid! I'm so glad I can reclaim that 30cm of space I lost by moving my entire desk back off the wall haha. Only issue is I need to find my measurement mic so I can recalibrate my system!

[@warpacademy]

Glad it helped! Yeah, much of the advice I've seen in speaker manuals is just dead wrong. Speaker designers care about frequency response in an anechoic chamber, and don't seem to give much useful advice for real-world situations that include putting them in a room. It's a fairly deep understanding of acoustics that's needed, but you'd think they'd be aware of this issue and the fact that once you create it, you cannot solve it using room EQ or realistic acoustic treatment. It's a damn shame so many people compromise their low end frequency response by following that wall gapping / speaker positioning advice without ever testing it themselves.

[@potitwist]

Outstanding! Thank you for switching the light on for me on this topic 🙏

[@warpacademy]

Glad it was helpful!

[@gabofortuna]

Thanks so much for the in depth video and real world measurements of your tests. These kinds of tests, results and explanations are INVALUABLE and I’ve struggled to find many videos documenting these topics to this degree. Well done as always, cheers!

[@warpacademy]

Thanks Gabriel. Glad you got a lot out of this one. Opinions are plentiful, but facts are rare. I like the data-driven approach with actual acoustic tests. Cheers and best of luck with your music!

[@g.s.3389]

very nice video, i learnt a lot, i noticed what you explained moving from one home to another the same speakers, although the difference is minimal for a not audiophile like me, i have noticed the difference. I moved at the end the speakers close to the wall as much as possible given the obstacles at the back :). thanks again.

[@warpacademy]

Glad it was helpful! Thanks for watching.

[@wr7629]

great video.... i have the exact frequency respond on time stamp 18:18. a dip around 1-2khz and a hump around 4-6khz. from your video, those frequency are 'flat' after the speaker is place up the back wall. 18:46 May i know why?

[@warpacademy]

Thanks for the comment. The ranges in my video are much lower and they null and peak are due to reflected bass energy from the front wall. In my room the higher frequencies are flat because of the amount of absorption in the room. Those modes are heavily damped and the treatment easily absorbs at those wavelengths. By moving the speakers against the wall you get the reflected energy mostly in phase and you even out the bass response.

[@mrsogood3531]

Very clear, love the drawings to illustrate the physics. I already knew about SBIR but it's always cool to see how other people explain it ! Such a nightmare to deal with ! The pos 1 is definitely the best if you don't mind the listening position. In my case i really wanted that optimised listening position and didn't want to have my monitors far away from me close to the walls. I heard subwoofer could help and it really did ! Because it lets you position your monitors freely while the low frequencies are carried by the subwoofer which i positionned right against the wall (since it's omnidirectional it doesn't even sound like the subwoofer is far) 👌

[@warpacademy]

Nice one. Thanks for sharing a bit about your experience. Yes, that's certainly one of the advantages of using a sub. You can position it separately from your monitors. Although subs have several substantial drawbacks IMO: 1) Because they're positioned in the bottom front wall/floor seam or a lower tri-corner they excite room modes far more than speakers up on stands. That's an issue in most rooms that have inadequate LF acoustic treatment. 2) You have to carefully phase align your sub with your tops. Subs have very rough phase alignment options (usually 0, 180, or sometimes in 90 degree increments) so usually you need to manually play with the distances (string test) or use phase-alignment software / hardware like a Trinnov. 3) And this is the biggest one...if you don't have 2 subs configured in stereo, now your entire low end is in mono and you cannot effectively mix your low frequencies as an engineer. Any professional studio has full range stereo monitoring, not a single mono sub. Of course, you could always use headphones to check stereo sub information. Those are just some issues I find. You may find them totally acceptable and that's all good. It's about getting good enough for you. Thanks for the comment!

[@merihakaboogie]

@@warpacademyI managed to get 25-105hz within +/- 0,6db in my listening position with dual subs in front corners. It was tricky to get the phase alignment just right but definitely worth it! My room is only 47 m3 so I’m super stoaked with the results!

[@ricksalt6860]

Great info , Thanks . I had a Yamaha NS10 on the left and a similar type speaker on the right but front ported . I was shocked when I realized after comparing the two each by themselves , the front port had 300 hz - ish info coming out of the port , most noticeable on vocals . Something you don't notice when using the ported pair but having an NS10 to compare , it was very interesting to discover .

[@warpacademy]

Thanks for sharing. Glad you enjoyed the video. Cheers!

[@Essential-Electronic-Music]

hands down the best video on this subject i've seen so far.

[@warpacademy]

Glad it was helpful!

[@sansproductionlounge8083]

I just moved my speakers!!!!!! 🤯🤯🤯 the difference is actually insane!! Lowend sounds full and juicy and I was able to calibrate it all by just moving the speakers and using the built in speaker tuning in the back of my Rokit 7s. Just amazing, Drew. You and David from mixbustv are absolute legends with what you’re sharing. I just feel so grateful that you’re sharing this gold. Thank you from the bottom of my heart. I am going to have to get used to this new profile, but it really does sound so much better and more balanced. It’s actually insane. 🙌🏼🙌🏼

[@warpacademy]

So happy to hear that mate. Yeah the difference in low end really is astounding when you get that reflection more in phase and you shelf it down. I’m stoked to have you on the channel and yes David is an amazing resource. I’ve learned to much from him.

[@DaPhunk73]

Thanks for a great video! Gonna try the monitors up against the wall again, have experimented with different positions out from the wall, and having the exact problems you describe..

[@warpacademy]

You're most welcome. Glad it was helpful. Yeah, this one is a very common issue in music studios, but easily resolved. I encourage you to run before and after acoustic tests in Sonarworks, if you have it, or Room EQ Wizard. Use the data to confirm the difference in room response. Feel free to post a comment or question if you need any advice going forwards. Cheers!

[@RoddSantiago]

wow this is huge, i had a problem with 140 hz being too resonant this helped me tons taming that, its still high but not overpowering, thanks.

[@warpacademy]

Glad you found it helpful, and that it made a difference to your room!

[@gesnerjr.gaugirard6831]

Thanks a LOT for those explanations! I will definitely give it a try because I have done DIY accoustic, I also have sonarworks and I feel my mixes so inaccurate within the low end. I was used to it my day to day routine but I figured out during my car test something is off in my studio under 100 hz, same feeling when I have gone to my best friend's home studio.

[@warpacademy]

Best of luck! Keep in mind that most rooms also have a huge amount of LF ringing under 100 hz which masks things down there. That’s just due to those frequencies being harder to control. So that could be an issue too.

[@gesnerjr.gaugirard6831]

​@@warpacademy Hi, I tested to place my monitors closer from the wall and I also moved my sweetspot a little bit by following the "bass hunter technique" from accoustic insider, the overall result before room eq correction seems a little bit more flat and low end is definitely more present. My room is fat from perfect but I can't do much with accoustic treatment as I am renting my flat. I will also test some other listening placement but I am already seeing some improvement. Thanks for your explanations :D

[@warpacademy]

Stoked to hear that! Be very careful applying room EQ to a space that does not have adequate acoustic treatment. Room EQ will most likely be detrimental vs making an improvement if you do not have controlled acoustics. Only after a decent amount of wideband absorption has been applied should you consider using room EQ, otherwise you can do more harm than good as the room EQ cannot discriminate between a reflection causing interference, and an issue with your monitoring like a cabinet resonance.

[@dwaynepiper3261]

Many years ago I read a lot of literature on room acoustics and if I remember correctly the timing of the reflection from the original signal has an important effect on our ear's perception. I think it was something like a reflection 5-10 milliseconds delay after the original wave is perceived as a separate sound by our brains. Less and it's perceived as the same signal. It would be interesting to know the calculated delay for the three positions and room modes from other wall reflections. We can not localize bass frequencies like mid and high ones. Is optimizing the bass hurting the other frequencies? Is the effect of room modes caused by reflection from back and side walls more important? If my memory serves me correctly you should be able to calculate the best speaker and listening position which will be different depending on room dimensions to minimize room mode effects. Was the microphone positioned in a room mode?

[@warpacademy]

Hey Dwayne. Thanks for the comment. I think what you're referring to is the human echo threshold. Although it can depend on the type of sound (transient vs steady state) and frequency, it's typically around 30 ms. But in some circumstances it could be shorter. You can test it yourself with a delay effect to see where you can start to discern a the delayed echo. I usually start to hear a distinct delay at 30 ms or so. In a music studio control room, you want to optimize all frequencies of course, and many other things, such as the decay rate of each frequency (addressing modal ringing), the stereo field and phantom center, the impulse response / ETC of the room (the liveness of the room as well as especially loud early reflections, desk reflections) etc. The low end just happens to be one of the most challenging aspects to optimize, which is why it's important not to create unnecessary problems through bad room setup and speaker placement. When your goal is a very controlled and accurate listening environment, you'll be using extensive acoustic treatment. Because of the frequency-dependent way that porous absorption works, mid and high frequencies are easier to control - hence the focus on getting the low end right from the start. All room modes are important, as is the spacing of room modes. The room modes are usually the most isolated and spaced out (IE uneven and lumpy looking in REW) in the low end. As you go higher and higher up, the room modes start to create a more even effect (IE the Bonello criterion). You typically would be designing a room based on one of the golden ratios using a room mode calculator to avoid stacking room modes on the same frequencies and ensuring the room meets Bonello. Although as you add more and more acoustic treatment those golden ratios get less and less important because you're damping them so heavily. In my room, we chose to maximize room volume rather than target a golden ratio. When you say, "was the microphone positioned in a room mode", do you mean in a node or anti-node? Cheers!

[@noself1028]

Thanks so much for this video. It's extremely informative and corroborates some other guidance I've seen on the subject of speaker placement. I'm looking forward to trying this method with my own speakers, in combination with Dirac Live room correction. Hopefully this technique works as well for stereo listening rooms as it does for studios.

[@warpacademy]

Hey mate. Glad this was helpful for you. This is unpopular advice with a lot of living room / audiophile folks. There's a lot of outdated or just plain bad setup tips out there that aren't grounded in any kind of actual testing or physics. Gapping your speakers out from a wall, 1/3 of the way into the room to "solve" SBIR is the biggest one of them all and that's why I focused on it in this video. Good low end response accounts for 30% of the listening enjoyment experience, even if you're not a professional engineer (per Floyd Toole). And there's only one way to get a relatively flat low end - it's to put the rearward radiated bass energy from the speaker as in-phase as possible with the direct sound. Gapping a speaker from a wall, or putting 6" of porous absorption behind it does not stop the out-of-phase reflected bass energy from causing low end interference - the distance and the absorption characteristics of porous absorption are not capable of that - at least not with that amount of time of flight and that thickness of absorption. So really, you must put your speakers against the wall if you care about low end response.

[@djvictornova9188]

This method works great on solving the dip and speaker efficiency.. But i also found that you also sacrifice soundstage depth wise. That's been my experience when placing my speakers close to the front wall..

[@warpacademy]

Hey hey. Thanks for checking out the video. What I would ask you is to define what soundstage means to you and depth. In the context of an engineering control room with reference monitoring. Here’s what I think. The sense of depth is created in the mix by the use of depth staging mix techniques. The sound of a mix can be further enhanced by reflections in a room but those always have a negative consequence on the accuracy of the response of the room and thus reflections are generally considered undesirable in control rooms. In audiophile rooms, which is not the context of this video, you definitely would want some controlled reflections and room ambience. But not for engineering generally speaking. This is why you will consistently see main monitoring built flush into the front wall in all professional caliber, purpose designed control rooms. So, if you’re listening for pure enjoyment and not accuracy or critical listening then go ahead and gap out the speakers. But if you’re in an engineering context that will be a bad trade off IMO.

[@djvictornova9188]

Thx for the explanation much appreciated. Soundstage to me is when your listening to a speaker and it sounds opened , You are able to hear reverbs , delays , that exist in-between the sounds . Yes there's left and right sound placement , and louder and lower sounds that give you a sense of depth. But for me its more then just technical mumble jumble , its how a song feels as a whole that creates good soundstage. The closer to the wall i placed my speaker the more it lost what makes a song shine and also the speaker shine. Its almost like you grabbed a great recording and reduced everything by 50 perct to MONO ... There's no way any speaker up against a wall could be natural. But i get it that its fixed same issues at the cost of other more important things.. Hopefully this makes sense.. Thx again

[@thePunkRockMix]

no its not just you saying this. it stands for example in the genelec manual for their SAM Monitors. I did it that way - pretty happy with the results.

[@warpacademy]

Thanks for sharing that.

[@thePunkRockMix]

@@warpacademy thanks for the video. And I can see it's relevance, because when I first read it 2 years back, I was a bit confused, why they told me to place the monitors so close at my walls 😀

[@warpacademy]

That's one of the rare examples I've heard of where a speaker manufacturer actually gets it right. Quite often they say to gap them from the walls, which makes no sense when you know the physics.

[@tomburden]

Really awesome video. This really improved my mixing position. There is a room simulator in REW this can illustrate everything shown in the video. Also added note the null in the first position can be adjusted by the width of the speakers. 1130/2x13= 99.5 hz. 13 would be a 13 foot room.

[@warpacademy]

Hey Tom. Glad you liked this one. And yes, indeed there is a Room Sim aspect of REW. It's very useful for showing your calculated room modes and how they line up with your test results! You comment about moving the speakers wider apart is a bit complex. If you have reflective side walls and a reflective front wall (which I don't - only my front wall is reflective) then you will have overlapping boundary reflections from both the lateral and front boundary. Moving the speakers closer to reflective side walls will certainly change the null frequency from that destructive interference. However moving the speakers further or closer apart laterally, but not changing their gap to the front wall, will not change that null at all. Because: The frequency of boundary nulling is related to the distance from the speaker to a boundary, and due to the need for symmetry in a control room, both speakers should always be the same distance to boundaries. In my room, the side walls are extremely absorptive while my front wall is massive, rigid and reflective. So in my tests I was able to mostly isolate the effect of the front wall SBIR. As I'm sure you know as well, when you move your speakers further apart from each other, you also must shift your listening position backward, which dramatically changes the acoustics as you now are in a totally different position with respect to your pressure nodes and anti-nodes. I'm glad you've found some improvement at your listening position. All the best!

[@tomburden]

@@warpacademy Thank you for the in depth response. Your channel is a great resource to the audio community!

[@warpacademy]

My pleasure, and thanks for the comment!

[@wattspeakers]

Excellent video. I think this will help viewers understand what happens when you have speakers close to or pulled away from walls.

[@warpacademy]

Cheers! Nice channel BTW. Your videos look excellent.

[@sansproductionlounge8083]

Thank you so much :)

[@warpacademy]

Thank you so much for helping to support what I do. You get the honor of being the very first person to ever use the Superthanks! Big ups. I super appreciate you sending me that donation, it really makes a difference.

[@sansproductionlounge8083]

@@warpacademy wooohooo!! 🙌🏼🙌🏼🙌🏼 you content is just awesome man. The detail, depth and science behind what you deliver just helps it all make sense. Love your work mate!

[@1973Cyberscotty]

You are so right about that, which you discussed about in the beginning. It is so true. Thank you very much.

[@warpacademy]

Glad it was helpful!

[@Rhekluse]

Great video! Congrats and good luck on your fresh studio build. It looks phenomenal! Edit: I believe speakers isolated on floor stands against the wall hold much different & much better results verses speakers isolated on a desk against the wall. Less build up of resonances and reflections. So floor stands ftw. However, I assume if speakers are to be isolated on a desk the best results may in fact be right up against the wall.

[@warpacademy]

Glad you enjoyed this one. We're in the final stages of the build now. Home stretch. Regarding speakers on stands, I'm 100% with you on that. I spoke on that in this video: kzbin.info/www/bejne/qH3Vi5eXnc12eac&. If your monitors are desk-mounted and also up against the wall, you're likely going to be out of an ideal listening position and too far forwards in the room. It's also likely that your monitors are going to be too low and the acoustical axis will be firing below your ears, necessitating you to angle them up - not ideal either. Stands are a much better option as they allow the listening position to be fully independent of the speaker position, such that you can configure the room in whichever way that works best. For stands, I really like the Ultimate Support MS-90 models. You can add sand or shot into the internal channel to add mass, and you can also feed cables through a separate internal channel for a cleaner look. They have decoupling points at the feet, where they connect with the floor, and decoupling points at the top where the speaker sits. You can also get an upgraded version of them with the Isoacoustics decouplers. I use those in my KZbin shooting studio to mount my Tannoy Reveal 802 monitors for general recreational listening (not mixing or critical listening work). Cheers!

[@Rhekluse]

@@warpacademy Thank you very much for the very courteous response! I appreciate it. I've been following you for a hot minute now, nearly over 13 years and I am really happy to see someone of your constant integrity grow from a humble studio to a full out custom design. Bless for sharing everything you have learned along your journey, Vespers! Bless!

[@warpacademy]

13 years? Wow! That's nearly at the beginning. I started the channel in 2009. Thanks for your support over the years and for following the channel for so long. Nice to still have you on board and getting value out of the videos. Cheers!

[@basveeren7436]

@@warpacademygreat video and interesting test! So now that the speakers should be against the wall, while not sit too close to that wall, the speakers should be spread wider in the room to keep the equally triangle right? (Wider then a desk is) This may increase the influence of the room? And any tips for someone who has a sit standing desk to benefit heath. Now I have speaker stands attached to the backside of the desk that moves along with the desk… they are quite close to me as the current desk is not so deep. Have a huge peak at 120 hz (using Clamp On Stative - gator frameworks. All tips are much appreciated!

[@warpacademy]

Hey hey. Glad you liked this video. Having the speakers close to the wall will help to flatten the LF frequency response. You should certainly maintain the equilateral triangle with your mix position about 12-18" forwards to the apex of the triangle so that your ears are in the path of HF sound propagation. Standing desks, while perhaps necessary, will wreak havoc on your acoustics. There's no way you can maintain acoustics while moving substantially up and down in your room as you'll be putting your ears directly on a pressure node or anti-node for your vertical axial room mode at some point. If you need to stand, and you need accurate acoustics, try monitoring on headphones if you don't get a good result. Having your monitors clamped onto your desk is also not a great setup for acoustics. This places them very close to you, will likely create comb filtering off the desk surface, and also will likely create acoustical coupling that will cause the desk to resonate heavily. Maybe an alternate solution is to have 2 sets of stands at 2 different heights. 1 for seated, 1 for standing height?

[@sebastiaanbosker1199]

Great video. How does it work when a Sub is placed in the room? Also flush it up against the wall and acoustically treat around it?

[@warpacademy]

Thanks. Good question. A sub will behave exactly the same way. If you put it out into the room then you’ll get massive cancellation and boosts. The best place for a sub is built into the wall flush (and then you phase align it using digital time alignment software) or placed against the wall.

[@sebastiaanbosker1199]

@@warpacademy Thanks a lot for your response and your videos. It really helps! :)

[@warpacademy]

My pleasure.

[@audiononsense1611]

As an acoustician, I'm going to offer some help to you and anyone else listening to this video!! (1) It's impossible to assume EQ is going to help with a 12dB swing on the low-end. At most 2dB is manageable and as you stated, moving the speakers forward can help. (2) Taking proper room dimensions out (for purposes of help) measuring room gain (knowing how is key) will tell you what treatments are needed and I can say no 4" panel is going to help with frequencies under 300Hz. I could go on however consulting is not free...

[@warpacademy]

Thanks for joining in the discussion. Nice to have some professional acousticians in the mix. I agree completely that large peaks and nulls to the tune of 12 dB are not going to be magically corrected and sound flat with EQ. The approach of using EQ, as I said in the video, is an added final layer to be used, if necessary, after acoustic treatment, speaker optimization, etc. I also agree that no 4" panel is going to help with LF response and I don't think I made such a statement in the video. However, a floor to ceiling absorber that's 5.5" thick with Rockwool Comfortbatt R22, air gapped from the wall, will most certainly put a dent in the LF. Although that's only just a start, and in this room we went with much thicker treatment. The 5.5" thick absorbers are more for home project studios with DIY treatment, not professional rooms. Thanks for joining in the discussion. Cheers!

[@rocknroller6975]

Excellent information, very clear and straight to the point. Question: can you recommend porous absorption panels? Thank you.

[@warpacademy]

Thanks for the comment. Glad to hear you found this one valuable. For porous absorption, I have a very detailed video about using that type of acoustic treatment here: kzbin.info/www/bejne/iYTRaXt7qKxrqNE. Watch that first. Then I have a video on exactly how to make the best DIY porous absorbers for only $250 here: kzbin.info/www/bejne/e3TEq3qwqtmejJo This video will show you how to wrap them: kzbin.info/www/bejne/hIrIqGiQpqyAbbM

[@rocknroller6975]

@ Thank you

[@joentell]

Good video and testing methods. 🙌 I also like this placement for the same reasons you mentioned. A few questions/comments: the 160hz dip you saw in the measurement you've attributed to floor bounce, but I didnt see it in the other measurements. I think that might be related to rear wall reflection. Another thing to note is that a dip in response caused by destructive cancellation cannot be fixed by boosting the signal since its also boosting the destructive reflected sound wave. Let me know if you disagree. Im open to being wrong.

[@warpacademy]

Hey there. Thanks for watching and commenting. You've got a great channel as well! Regarding floor dip, good eye. In the floor dip calculator the dip frequency works out to be 158 hz, which is bang on where we're seeing the dip. You're correct in that it doesn't show as much in the other measurements, but it can easily be getting blurred by constructive interference from the front wall SBIR when speakers are offset from the wall. If the other boundaries, such as the back wall, were not heavily treated then it would be conceivable that it could be a reflection from one of them. In this case, however, we have 3.5 feet of fibreglass in the back wall, 2 feet in the ceiling and 1.5 feet in the side walls so far. The absorption coefficient for that depth of treatment is high enough (0.85 to 0.9 at 150 Hz) that it should eliminate those treated areas (which are floor to ceiling) as issues. But we'll only know for sure once we finish the room and get a desk in there. Very insightful observation on this one. Regarding the EQing of the drive signal, this is what I'm basing my comments on... It's not information coming from me. I haven't tested this personally and I'm relying on research from the AES. Take a look at the Journal of the Audio Engineering Society, volume 33, page 127-132 (Clarkson, Mourjopoulos and Hammond). Also the AES book Recording Studio Design by Philip Newell, page 332-334, which states "Near perfect response at optimum listening position after correction (with digital adaptive EQ)". This example was based on a test where a loudspeaker was positioned on a stand, part way through a room (exactly as I did in position 2 and 3), after which digital adaptive EQ (like Sonarworks) was applied. This section of the book is also key to understanding why and how the correction can occur, "A non-minimum phase effect (such as when a loudspeaker is freestanding in a room, and not mounted at or in the wall) cannot be universally corrected by equalization (alone) of the loudspeaker drive signal. Even perfect amplitude correction could not restore the original phase response by any known practical analogue means. Only by digital signal processing could an almost perfect response be restored. Adaptive digital filtering can model, very accurately, the inverse phase responses necessary to correct either the minimum phase or non-minimum phase components of a transient or steady state response anomaly. By means of measuring microphones, modelling delays, and adaptive filtering processes, the digital systems can be made to 'learn' what a given room will do to a loudspeaker response, and apply acausal corrections to cancel the disturbances [acausal, in this sense, means that by means of a signal delay, the measured response error is fed into the drive-signal, in inverted form, to precondition the output to anticipate the error." -Pg 334, 11.5.2 Digital Correction Techniques, Recording Studio Design, Philip Newell, Audio Engineering Society. This is exactly what Sonarworks is doing under the hood. Let me know it that makes sense. Cheers!

[@themattprofessor]

@@warpacademy The Quote from P.Newell doesn’t address the SBIR issue, it really doesn’t matter what leaves the loudspeaker at a given time, as the reflected wave will itself be changing with the generated wave, always in antiphase at that centre frequency that is a 1/4 wavelength, and frequencies either side in decreasing amounts.

[@warpacademy]

Hey mate. The quote from Newell does indeed address this. He's speaking about the ability of non-minimum phase response modifications (speaker on a stand away from a boundary) to be corrected by digital adaptive EQ. Take another look over the quote, or read the book as it seems quite clear and discusses the mechanism of action (correction). But seeing as it's not seeming clear to several people on this thread (and because I'm always up for understanding a topic more deeply, or open to being wrong), I followed up by speaking with Philip Newell directly on this matter, and here are his comments on this specific topic: "I stand by what I said in the section that you quoted from Recording Studio Design, but it has to be taken in context. Acausal filtering and signal processing, WITH A MODELLING DELAY, can correct for the room boundary effects, but only for a very small region of a room -- say a very restricted 'sweet spot'. Elsewhere in the room, the response may then be much worse than before the correction. So, for example, if someone must work in an acoustically-poor room, this type of processing could greatly improve things at a restricted listening position, which may be beneficial to a single user, or it may 'somewhat' improve things over a slightly wider area, but it cannot make an overall improvement to the room acoustics. When one place is improved, another place will suffer." The key thing to understand here is that this is not just amplitude correction from a standard EQ. A platform must have a modelling delay feature to compensate for boundary effects and phase. So it is indeed possible and Philip has specifically confirmed this. Now, I also followed up with Sonarworks, who also confirmed this is possible with phase shaping. I was mistaken in that their current platform doesn't do phase shaping, so I stand corrected on that. They plan to roll this out in a future release.

[@stevenrayphoto1280]

Really great accurate information! Sonarworks is an excellent tool for finding problem areas in your room. I don't use Sonarworks to correct any problem areas, I think it's better to treat the room . Thank you for the info!

[@warpacademy]

Definitely agree with you that your focus needs to be on treating the room and getting as optimal acoustics as you can. Then, you can use room EQ to address remaining issues.

[@bernhardadam4700]

THX for this video. But one Question is still left. In my opiniion you can´t correct dips as long it is the result of a phase/comb filter effect. What I know is, if you push level up the frequency of the dip then you push the level of the signal that produces the dip, too. So the dip must be the same. Or is there something I don´t see?

[@warpacademy]

This is a very good question. If you were to have the speakers off the wall, such that there was a phase difference, and only use normal EQ to adjust the drive signal, then you'd be totally correct. Normal EQ would just boost the offending frequency, and still cause the dip. However, some forms of digital adaptive EQ is also taking phase into account. For evidence and corroboration, read Audio Engineering Society Recording Studio Design by Philip Newell, Page 333. He confirms this in the acoustic testing. I thought that the Sonarworks platform was doing this, but I was mistaken. Also read the Journal of the Audio Engineering Society Volume that I reference in the video on screen. This is the paper to which Philip Newell refers in the book.

[@warpacademy]

I've updated things with a pinned comment about this at the very top of the comments. Please refer to that. You definitely can correct the response and the comment explains how. Cheers!

[@yassinetalbi5884]

@@warpacademy What EQ should you use instead of a "normal" EQ ?

[@warpacademy]

Sonarworks is the EQ platform I'd recommend. Or perhaps a Trinnov if you have the budget.

[@Ultimatestudiosinc]

Fantastic! This is the best explanation I have heard. You literally helped me solve a big issue that has plagued me for a while in the low end consistency of my entire control room. AND.....made the stereo image absolutely phenomenal. Re-running my Sonarworks calibration right now to dial it in. Thank you!

[@warpacademy]

You're very welcome! Glad to hear this helped. Hopefully you'll enjoy the new improved bass response. Also, if you don't mind sharing, I'd love to see screenshots of your before and after Sonarworks testing data. Send it in via the Warp Academy support form if you'd like to. Cheers!

[@konjstip6156]

Hello again, I might already asked this question, but can't remember. Pardon me if I had. How did you secure a cool air airflow behind the amps of the speakers inside the wall ? Thanks

[@warpacademy]

Hey hey. I didn't ;) I live in Canada! After many tests, they run optimally for all my mixing sessions. The monitors have heat deactivation technology on them, which as triggered a couple times, but only when I have the room filled with people and the monitors running loudly (dance party). If I want to, the KH420s have amp-relocation kits where you can take the amps off and I could put them in the adjacent cold room with fans. No plans for that tho. Cheers!

[@konjstip6156]

@@warpacademy Thank you for your answer!

[@warpacademy]

My pleasure.

[@barbiegamaestan456]

Great video. Note that bass frequencies are not omnidirectional especially at monitor frequencies. The lower you go, higher the polar response relative to the speaker and cone size. I find around 50hz is where the effect becomes hard to discern by ear.

[@dananskidolf]

> The lower you go, higher the polar response relative to the speaker and cone size. I _think_ it's the other way around - dispersion always becomes quickly more omnidirectional (less polar) as you go lower, but this turning point is lower the bigger the speaker/cone. E.g., you get roughly omnidirectional bass for these beastly KH420s at 35Hz but for a diddly little 8010A it's more like 100Hz. Do you have a monitor in mind that doesn't have this (other than cardioids)? > I find around 50hz is where the effect becomes hard to discern by ear. At 50Hz you can't tell what direction bass is coming from because of how our ears determine location of sound sources. So if you move around a monitor to try to tell if the bass is omnidirectional, you will mostly be hearing the effect of the room modes, not the speaker's dispersion.

[@warpacademy]

Hey hey. Glad you liked the video and you've made some interesting and correct observations. I suppose I would consider it rather semantics if the bass is truly omnidirectional or just nearly omnidirectional. What is much more consequential is that there is substantial rearward (and lateral) radiation of low frequencies. The portion of the LF and the amount of sound pressure level relative to on-axis will depend on the driver size (as you correctly pointed out). The larger the driver relative to the wavelength of the frequency, then the more "beamy" that frequency will be. When λ = membrane diameter (or shorter) is when it really starts to happen. For example, the HF of my single-driver DMAX Audio Supercubes 5 is extremely directional. You notice the sweet spot diminish if you move your head as much as 2" off axis. The main point I make in the video is that nearly all speakers marketed as "studio monitors" perhaps save for the cardiod designs will have significant rearward bass radiation. And that causes this predictable boundary nulling, regardless of variations in the polar pattern of LF radiation, because none of the speakers actually reduce the amount of rearward radiation to a frequency that is not problematic in typical rooms and configurations. That's my take on it, and I've never yet tested a studio monitor or studio room where this has not been an issue. Thanks for the comment and disucssion. All the best!

[@konjstip6156]

Hello! I was wondering, have you ever published the measurements from the finished studio? Cheers

[@warpacademy]

Hey hey. I have yet to do a video with acoustic testing on the final room. I've done the measurements and they turned out amazing. I'll slot that in for a future video. Cheers!

[@kadiummusic]

Don't position your monitors until you've identified the optimum listening position. Then position your monitors using the phantom centre method. Then using REW treat your room acoustics the very best you can. Finally use ARC 4 to tweak to taste. Bingo, did this for new mixing room and it sounds incredible. All details at Acoustic Insiders on KZbin. 😎

[@warpacademy]

Hey mate. I've watched those videos so I'm aware of what they advice; I just happen to disagree. Jesco talks about the importance of setting your priorities when designing a studio. Well, I place a very high priority on bass response / accuracy and you will never get a good bass response by placing your monitors out into the room. That's physics 101. SBIR / boundary nulling will shoot you in the foot. Do I mean that I don't care about phantom center, or a really solid sense of stereo field? Not at all. It's just not that hard to do. When you have enough side wall treatment to attenuate or absorb lateral reflections, the phantom center is amazing. It's reflected energy and diffraction that blurs your sense of phantom center, so you deal with that with absorption. Easily done. What is not easy is trying to "fix" your bass response after setting up your room in a way that ignores SBIR in the low end. You cannot simply place acoustic panels behind your monitors. That'll only partially reign the problem in, but not address it fully as the depth of treatment necessary to kill the reflection is enormous. And if you think I'm the only one who is saying this, I'm not. What I recommend is consistent with what Philip Newell and Wes Lachot say. They are professionals who've built some of the most important and accurate rooms in the world. As you may know, Wes Lachot is the creator of the "38% Rule". Here's what he has to say about the priority that bass response should take, and placing the speakers on the wall or out into the room. "All is won or lost in the bass." "You can buy your Focals or whatever, but you’ll just be guessing with your bass!" "You can move them around for years, but you’ll just create new problems." "You should always put speakers against the wall unless you have a very deep room! 9-10 feet from the wall in a 30 ft deep room, otherwise no."

[@taylorforrestmusic]

This video was PERFECT thank you

[@warpacademy]

Thanks!

[@tomburden]

Really awesome video. I would love to get a video on an in debth comparison between sonarworks and ARC 4.

[@warpacademy]

Thanks for the suggestion! I'll add it to the list.

[@ThirdEyeFX]

Hi and thanks for this very helpful video. I have 2 subs (facing each other L R of mixing position) and Sonarworks. What I saw in this video helped me see that there's some big dips under 100hz and the correction is actually BOOSTING the signals and making the subs work overtime. Had no idea that was happening. I'm going reverse-phase one sub and retest. Hopefully the dips become spikes and Sonarworks can pull those puppies down for me. Thanks again for this video.

[@warpacademy]

Hey hey. Glad this one was useful for you. Do you have your subs configured in stereo or mono? That matters. I would run them in stereo, personally, so you have a proper stereo full-range monitoring system. Also, using the phase control is your last step. Don't touch that yet. Physically position the subs correctly. The best position for subs is built into the wall with their ports flush with the wall surface pointing into the room. The next best position for subs is directly against the wall. If you have a dip under 100 Hz, it's likely due to some form of boundary reflection causing interference. Move the subs first to get the LF frequency response as clean as you can. Then tune them using the controls. Hope that helps. Cheers!

[@ThirdEyeFX]

@@warpacademy They are in stereo. I tried the phase flip and it didn't help - so it's at 0º again. I'm using REW to get the Before looking good before I run SoundID again. Fingers crossed! Questions: 1) Is it better to run SoundID with the speaker levels slightly louder, so that there's more peaks? Is there an ideal room SPL to start from? 2) Do you have SoundID's Listening Spot enabled? I've head people say that it doesn't sound natural so they turn it off. They also mention adjusting the Mix knob for that reason. - seems a little strange to me because it would add delays and phase issues back. Thanks again!

[@warpacademy]

@@ThirdEyeFX hey hey. Ideal SPL to shoot your room is 85-90 dB SPL-C weighted. Louder and you may blow up your speakers. Quieter and you will not excite mechanical resonances. Again, move your subs physically before adjusting phase. I use SoundID Reference at 100% wet. You want that so it properly phase aligns your speakers. Don't fuss with the wet dry. I would use the minimum phase option. I would use Listening Spot.

[@ThirdEyeFX]

@@warpacademy Will do. Thank you!

[@warpacademy]

You’re welcome.

[@plake01]

My experience is that you should not trust the graphs in Sonarworks. In my case the software was boosting 100 Hz by 7 dB and the correction graph showed a nearly flat line. I have double checked it with REW and the dip was still there, even a little worse than before. As far as I can understand this makes sense. If I raise the energy of a frequency coming out of the speaker, the energy of the reflected wave from the frontwall also has more energy, so as far as I can tell raising the level of a frequency to fix a destructive interference caused by SBIR doesn't work.

[@warpacademy]

Hey mate. Thanks for joining the discussion. It's a smart idea to shoot the room with REW, if you know how to use it, to get more granular with your test results - if that's what you're looking for. I did the same thing. I shot the room with REW and Sonarworks SoundID Reference at each location to corroborate my results. If Sonarworks is boosting 100 Hz by 7 dB you have a substantial acoustics issue in your room. Are your speakers gapped from the front wall? Sonarworks can't correct for a incorrect room setup. It also can't correct for a lack of appropriate acoustic treatment. As I said in the video, don't create time-domain acoustics problems like SBIR and then expect to get good results. Sonarworks should be applied after room setup is optimized, and you've acoustically treated the room. It sounds like you have SBIR off your front wall, ceiling, side walls, or a combination thereof. Feel free to reply with information on your room and I'd be happy to advise on how to fix the 100 Hz dip. The issue of boosting an SBIR null has come up a lot and I've posted my thoughts about this at length in the pinned comment up top. Please refer to that. The Sonarworks platform can be a bit misunderstood if you don't know what's going on underneath the hood. It's not actually flattening the frequency response in the same way that REW would show it. It's taking into account the psychoacoustics of how we perceive a flat or balanced sound. You must account for the fact that the human ear is not linear and our ears or much less sensitive to certain frequencies. This is where equal loudness contours come in; they demonstrate that very well. There has been much research into what curve produces the perception of a balanced response. Sonarworks has done their own research and the "flat" target represents what we perceive as a flat frequency response in a a typical room. Typically that means a slightly exaggerated low end and a slightly depressed high end. It obviously depends on how the room is treated and the directivity of the HF drivers. Read more here: www.sonarworks.com/whitepaper

[@DomSchiavoni]

With all this focus on the non-directional freq interaction with the Front Wall could you please comment on the other room surfaces like Side Wall, Ceiling, & Floor. Would running the same experiment with a monitor up against the sidewall then pulled 2 & 4ft towards the center of room have similar results? I assume not as you would have just said stick em in the corners and be done with it...

[@warpacademy]

Hey Dom. For sure. For that, please watch the detailed design video on my engineering control room: kzbin.info/www/bejne/a4fVeGWBlKpqp6s The side walls, ceiling, and back wall are all treated with various thicknesses and densities of porous absorption and air gaps in strategic places. The floor is left hard and reflective, as is customary in control rooms, and helps out the function of the rear wall scattering slats adding some energy back into the ETC.

[@paulbradshawguitar]

thanks so much for doing this, this is definitely an OCD inducing topic, trying to get the best results, in small rooms (like the one I have) it's really nice to see some science and numbers behind speaker placement , this has been really helpful in optimising my small room setup , kudos

[@warpacademy]

Right on. Yeah testing this stuff first hand is where it’s at. There is a lot of partially wrong or misinformation around. In a small room also make sure your listening position is well away from the center of the room. You’ll find there is a pressure node there and if your room is square or close to it you’ll get overlapping modes. Cheers!

[@paulbradshawguitar]

@@warpacademy thanks 🙌good call on the listening position/center of the room, i'm thankfully closer to one wall than the center next step is optimising some small bits of extra room treatment (more bass traps/first reflection points) and then redoing room measurements for corrective EQ (I'm using REW to measure and then Equalizer APO and EQ plugins in DAW as correction

[@warpacademy]

Awesome. Sounds like a great approach. And you nailed it; do your room treatment first, and only then use room EQ. Keep in mind that room EQ is only able to make slight improvements. The heavy lifting is done with room orientation, speaker positioning, listening position location, and acoustic treatment. A big novice mistake is thinking room EQ can "fix" time-domain issues, and most issues in a music studio are time domain and not frequency domain. For example, room reflections are a time-domain issue.

[@paulbradshawguitar]

@@warpacademy totally, the room EQ was a big fix in my case (huge desk / room resonance around 128hz) I'm curious if/how this will change with some extra room treatment coming in, moving the speakers back has been amazing in any case, spent this morning just relistening to music again, lots of fun

[@warpacademy]

@paulbradshawguitar Hey Paul. Your desk reflection (and the resulting comb filtering) as well as your room resonance are time-based problems and room EQ will not effectively fix those for you. The desk reflection is due to a slightly longer time of flight between the reflected signal bouncing off your desk and the direct path. Because the EQ is not compensating for the time delay of the reflected energy, it's of little use. Similarly, your room resonance (due to a room mode ostensibly) is a time-based problem. Energy is getting reflected back and forth between your boundaries, creating a longer decay time. Note that I said *time*. A "correction" EQ to compensate for this may look like a subtractive bell. This would accomplish the task of putting less energy into that mode, but it wouldn't do anything about the long decay time. That longer decay time will sound louder to you, psychoacoustically, as well as have a masking effect on the direct sound. The only thing that can correct decay times in your room is acoustic treatment (passive or active). SoundID Reference is great at time-aligning your speakers so they're in phase, it's great at correcting for driver / channel imbalance, and cabinet resonances. Use it for that. The other stuff you'll have to do with room design, setup, speaker positioning, listening position, and - crucially - room treatment.

[@RYOKER]

This is soooo pro and satisfying. TY

[@warpacademy]

Cheers mate. Glad you found this one useful.

[@eViperRabbit]

Wow. Great video. I learnt so much! Does your advice at the end apply to hifi systems for music listening, not mixing?

[@warpacademy]

Glad you got a lot out of this. The general thinking in hi-fi circles is to move the speakers away from the boundaries in order to "reduce the effect of SBIR". My big question to that school of thought is, exactly HOW do you think that is going to reduce SBIR significantly enough to flatten out your bass response and avoid a large null. People might answer that when sound travels a further distance, it loses power. While that is correct, the losses you get due to increased time of flight are totally insufficient and you will still get a dramatic null from the out of phase reflection. And now the out of phase reflection (which always causes a null at the 1/4 wavelength frequency) is simply lower and even more problematic to address with any kind of acoustic treatment. It's a losing game that doesn't make sense when you fully grasp the physics involved. Also, I think that the people who follow this advice and gap their speakers either A) Aren't prioritizing an even low frequency response in their system, or B) Aren't actually testing their room with room testing software, or both. When you test your room, you will see the effects in the frequency response clear as day. It happens in every room that's a rectangle or square. And you'll hear the destructive effects of the null (and constructive effects of the peak) if you listen and care about the low end. 30% of the perception of quality in music is the low end, so you must get that right if you want an accurate high-quality (IE high-fidelity) experience. Reference on that is via Floyde Toole author of Sound Reproduction and former consultant to Harman.

[@igoryakunin685]

In the first example with the constructive boost of the 35hz, I udnerstand the speaker can be corrected to work less, but how does that affect the bass tightness, accuracy of the bass?

[@warpacademy]

Hey hey. Great question. You can think of it like this. Bass accuracy and tightness, or transient response, are all heavily smeared by out of phase reflected energy. So the name of the game is to attenuate reflected energy as much as possible in your room (acoustic treatment) and then to get any reflected energy you can't deal with easily (IE low frequencies) as IN phase as possible. Putting your speaker against the wall is getting it as in phase as you possibly can, without going all the way to flush mounting it in the wall. The only other option is to move the speakers SO far into a huge room that your'e at least 3 meters from the front wall boundary, but still have at least 3 meters to your back wall to avoid early reflections there. Not many rooms are built that large, certainly not modern control rooms. Also, it's possible to use a sub (placed in or against the wall) and then you're more free to position monitors that are highpassed. All the best! Hope that helps.

[@igoryakunin685]

@@warpacademy you know, sometimes I leave comments without expecting an answer, escpecially not that detailed from the author itself, so thank you very much for the lsson that was learned today!

[@warpacademy]

My pleasure! I can't always reply to every comment, but I definitely try. Glad you found this useful. Cheers!

[@davidstevens7809]

Sir . Im without words..I have much to discuss even though Ive been in the audio business all of my life..time to hit the books..thanks..

[@warpacademy]

Hey David. Yes, there are a lot of people giving speaker setup and room orientation advice who have never studied acoustics. Acoustics is a science and all of the books I've read agree and are consistent on this topic. But no book or theory can replace real world experience with acoustic testing. So that is what I did in this video. Real world situations, real testing, real data.

[@riktascale4]

Thanks for this. Question, is the front wall in your example, the true wall or the receptacle wall with treatment? I have a dip at 123hz. Should I remove my 10" treatment from front wall and redesign it to place monitors further up against the front concrete wall or will this not help? I cannot flush mount them because they are footprints 01 with a sub.Thanks.

[@warpacademy]

Hey hey. My pleasure. Here's my completed room: kzbin.info/www/bejne/jpeykJWqecqLoMU. You can see the final wall there. In this video though, all you see is the isolation shell where the wall is flat, and not angled for a 30 degree toe in. So, to be clear, a second wall is built inside of the isolation shell - made of layers of plywood and MDF, glued and screwed together to make a rigid, massive baffle. Holes are cut out for the speakers, but cut just large enough that the wall does not contact the speaker baffle. You don't want contact. Yeah, I'm not a huge fan of Barefoots due to side side bass radiator. They're great speakers, but that prevents a flush mount. I would place them as close to your front wall as possible, and then create trapping all around them. Above, below, in between, and in the corners floor to ceiling.

[@gjani1980]

Thank you, I didn’t know that information. So I can put back to the wall even my Adam T8V’s as well.

[@warpacademy]

No problem 👍. And yes you can and should place your monitors there. Just make sure to shelve down the LF to account for front wall acoustical loading. You probably have EQ controls for that on the back of your speakers.

[@KevIn-qc4dr]

Wow!! What a great video! Thanks for sharing. May I ask what headphones are you wearing?

[@warpacademy]

Cheers Kevin. I'm wearing Audeze LCD-5 headphones. Amazing for mixing and mastering. They're my main cans.

[@lawrencescotto]

One question I have with that against the wall placement. With the Speaker responding the way they do against the wall, if you were to move the speaker a very small amount, would help to correct that rise on the low end? I'm thinking that it may do just that BUT, a small movement off the wall may create a problem in a different frequency area. Your thoughts?

[@warpacademy]

Hey hey. I like where your head's at with this. Good to start to experiment and think things through. The concept to really get here is that of minimum phase. IE, the frequencies that are in phase completely or nearly completely with the direct sound. Very close to the wall will create a more well-behaved low shelf like boost. This can easily be corrected. However, even a relatively small distance from the wall will delay the bounce far enough that you get substantial nulling. Test the setup yourself with REW to see how far you can move it. But the key thing to realize is the bass boost is not a problem. The easy solution is simply to EQ with a subtractive low shelf. Or, you may actually like the lifted bass response. Many people these days seem to prefer a bass lift in the bottom end. I do (not a big boost, but 1-3 dB can sound great, given that our ears are less sensitive to SPL in that region).

[@thmbackspace]

You test your speaker without any paneling but what happens when you install panels behind the speakers. Are mesurments the same or you need to do mesurments again or you finish studio without adding panels in the back of speakers? Thanks for answering. Very nice video by the way. Respect 💪✌️✌️✌️

[@warpacademy]

Hey hey. Good question. Many people mistakenly think that you can address the bass reflection by simply placing a panel behind the speaker. You cannot. The frequencies that we're talking about are very low, so low - in fact - that they are below the effective range of porous absorber panels. They won't work with frequencies that low. So no, it's not a solution. Watch this GIK video where they discuss this. They are one of the few acoustician-run companies out there who get it right: kzbin.info/www/bejne/imKTkICCfLR1nMU Cheers!

[@thmbackspace]

@@warpacademy thanks for answering

[@warpacademy]

My pleasure.

[@robertopistolesi2735]

Hi and thank you very much for this video. You're talking here about placing speakers with no treatment at all, if I'm not mistaken. What happens when you place panels behind the monitor, then on the sides for first reflections, and a cloud over the listening position? Do the rules you are talking about here still apply? I have been just suggested by a friend to move my speakers at 50 cm from the heavy panels they were super close to. Could you maybe elaborate a bit more on this kind of scenario? I also have other panels on the back of my listening position, but still I am not very able to understand what's going on in my room

[@warpacademy]

Hey hey. This is a great question. I'm talking about being in a treated room, not an untreated one. This advice is for music studio control rooms. As I said in the very beginning of the video (and show) the side walls, ceiling, and back wall in my test were all treated. In my completed room they were more heavily treated, but already in these tests the room had much more acoustic treatment than most of your will in your studios. Your friend, why did he say to move your monitors forwards 50 cm? Always ask people to explain their reasoning. What are they basing that advice on? I can't think of any reason to step the monitors forwards, except perhaps if you're highpassing them because you're using a sub for the LF. If so, you'd better make sure the sub is right against, or built into, the wall. Otherwise you'll suffer the same boundary nulling. The advice I often hear is "Move your monitors forwards and place acoustic panels behind them." That's bad advice from people who don't understand the physics. The problem frequencies at play here are bass frequencies. That is what's causing the nulling due to rear / spherical radiation of LF. Can you deal with low frequencies with your acoustic panels? Probably not. Bass frequencies can only be absorbed by super deep porous absorption (typically made of 2 densities), true 1/4 wavelength bunker traps (impractical in most rooms), active bass absorbers (super expensive), waveguides (a la Tom Hidley or Philip Newell - also impractical in most rooms), or pressure-based diaphragmatic absorbers (I bet you're not using those). If you're just using standard acoustic panels that are, perhaps up to 6" thick, then all of that problematic LF will be below the effective range of the absorber. Once you drop below and absorption coefficient of 0.7 the panel is more or less ineffective. So what you need to do is look at the frequency-specific absorption coeffiicient of your panels you plan to use, and I expect you'll find that they won't be of any help if you place them behind the speaker. What's guaranteed to work is placing your speaker against the wall like I show, and treating all the other surfaces in the room (side walls, ceiling, back wall) as well as the area in between, above and below your speakers.

[@danielhouse2895]

Makes sense. All of this. But I lose a lot of soundstage that close to wall. 28.5 inches I get the best soundstage without losing much bass

[@warpacademy]

Hey hey. Yeah if you don’t find the loss of bass a problem then locate them where they sound best. For my application, in a professional engineering studio, there is no loss of bass at any frequency that’s acceptable. LF frequency response is paramount. Also in terms of sound stage, the perception of sound stage is going to be due to lateral reflections and the acoustics of your side walls and perhaps your ceiling and floors. I wonder in your case if moving the speakers and forward and back is causing the reflection path to strike different materials?

[@satriany31]

Hello, Do you want a flat target curve or a tilted or Floyd toole target curve? Or do people in studio always want a flat curve at listening position? When you experience some listening fatigue do you change the tuning? Regards Greg

[@warpacademy]

Hey Greg. For me, I prefer the Bob Katz approach with a little low end lift. It can be interesting to experiment with a gradual, progressive HF rolloff as well (per Katz) but I don't find I'm a fan of that in this room and on these monitors. I don't make adjustments for listening fatigue. I take breaks. What I do make adjustments for is monitoring sound pressure level, because...Equal Loudness Contours. The ear is much less sensitive to extreme LF and the psychoacoustic perception of LF is very compressed as you increase SPL.

[@satriany31]

Thanks for your reply, interesting. I am just an audiophile, I design my own active speakers and I have a room which is half treated, some csd side walls and plenum plus corner traps behind the speakers. It helped a lot to measure the room plus speakers and for bass and clarity. Of course it is not perfect. I also have directive speakers with mid horn, hf horn, and ripole subwoofer at 80hz, this helps not sending energy to the room. I read about Bob Katz and I think this is a little bit what I do modestly. I also compare with my neumann ndh30 eqed with oratory1990 profile. Then it sounds pretty similar. If I want to retrieve the same amount of details with the speakers I have a more fatiguing experience. I don't know why. But we are talking of tiny differences. Regards Greg

[@warpacademy]

Sounds like you have a strong interest in audio and speaker design. That's a neat passion. I know very little about designing speakers, but I do enjoy listening to good ones in a good room! All the best Greg.

[@BentPerception1]

Hi this is a very informative video on speaker placement, thankyou for the detailed explanation, could you also give help for the addition of a studio sub, and where would this be placed? Is the best position parallel to front of monitor speakers but still very close to the wall if not against?

[@warpacademy]

Hi there. Thanks for watching. With a sub, that complicates things for sure. Detailed acoustic testing and tuning is necessary. Some things to keep in mind. The sub is on the floor, so the distance from the listening position to you will be longer due to the downward angle to the sub. So typically you'd want the sub to be equidistant from your monitors, meaning the monitors would be in front of the sub. This keeps everything in phase. But many subs have phase adjustment so you can adjust that as well. Typically you'd want the sub loading against the lower front corner of the room (where the front wall meets the floor). This will increase the amount of LF energy it's creating. From there, you can move the sub left or right to change its distance (and phase) or adjust a phase parameter on the sub. The other consideration is if the sub is highpassing your monitors. Basically, you want to very carefully test the room and experiment while tuning the sub.

[@jakubwoziwodzki6907]

Hey great video! Thank you for sharing the knowledge and sources. You mentioned back ports and the very low-end. However Im curious how does all that affect the midrange and high-end. I would bet there are some sacrifices (maybe not that excruciating in a standard box - however open baffles might be a different story). Perhaps is a bit more tricky to measure - but do you have any idea how does placing speakers near walls affect the perceived depth, width, and height of the soundstage? Open baffles that go down low with big drivers and some physical design optimization can achieve constant directivity throughout the whole spectrum because of the dipole configuration and CD horns. I’ve heard countless times that giving them lots of space is ideal. I wonder what is your take on this? Do same principles apply? What should one be wary about when playing with placement of such speakers? Great video once again! Keep’em coming:)

[@warpacademy]

Glad you enjoyed it and thanks for the kind words and questions. I have no experience with open baffle speakers / dipoles. That's because my area of expertise is studio reference monitoring and I've never seen that design used. Have you? The closest I've seen is a hard-flush wall mounting (like I have) that approximates an infinite baffle, but still with front ports operational. Bass directivity is forwards only. Zero edge diffraction. As a mixer, I also work in a non-environment room, which is more or less a hemi-anechoic chamber with a hard floor. It's a very controlled environment with very short T30 times, and ruler flat low end response and full frequency decay times. Not everyone wants to work or listen in a room like that as there is a sense of "no room at all" in the perception of it, acoustically. You will always want to opt to keep the acoustic axis of your monitors at ear height for any control room / critical listening room. Keep them away from side walls, otherwise you'll get a change in the low end response (even bigger boost) and more SBIR to contend with. Even with fairly deeply treated side walls, you'd likely still get some boundary coupling effects. You cannot correct the destructive interference from SBIR with currently available room EQ systems, so don't create that problem in the first place IMO. In a setup like this, where you have much more of the direct sound and much less reflected energy, you will have vastly superior stereo field and imaging, as well as an accurate sense of depth and height. If you want an exaggerated sense of depth and height, then you'd likely want to aim for more of an audiophile listening room that is more "live" than a control room. To achieve that, you can add QRDs to the back wall, front wall, and even the ceiling, as well as porous absorption. This will give a larger sense of 3D envelopment, at the expense of longer decay times, more erratic frequency response, and masking of the direct sound within an interval that is unsuitable for audio engineering work, unless the room is huge. Read this article, it's very good: arqen.com/acoustics-101/room-setup-acoustic-treatment/

[@jakubwoziwodzki6907]

@@warpacademy thank you for the detailed answer and source. I will look into this further as I’m finishing a man-cave project. My listening room is still pretty bare but with high potential. However I have made some measurements and seen some simulations confirming my worries with placing full range dipole speakers too close to the wall. There are some abnormalities with the radiation pattern and directions. In the end what I’m aiming for is a slightly more reflective environment than it is acceptable for audio engineering work however I love to approach the problem from this very analytical perspective. Thank you once again and take care!

[@warpacademy]

Best of luck with the project. Cheers!

[@JaguarPanda]

What about the 38% rule? is placing the speakers right against the wall a better solution? (for a small room)

[@warpacademy]

Hey hey. Very good question. The infamous 38% rule was created by master acoustician and studio designer, Wes Lachot. Here is the post Wes made about it: repforums.prosoundweb.com/index.php?topic=21551.0 The vast majority of people misinterpret this "rule" that is actually just a guideline. That guideline was intended to locate the mix position away from the center of the room and to avoid pressure nodes and anti-nodes, especially overlapping ones, due to boundary spacing. It's important to note that Wes stated 38% for control rooms that are 20' deep at least and where the speakers have been flush mounted into the wall, like my control room, and not for speakers on stands: kzbin.info/www/bejne/jpeykJWqecqLoMU&pp=ygUad2FycCBhY2FkZW15IHN0dWRpbyByZXZlYWw%3D I've spoken to Wes directly about this. Studio design and room setup is all about priorities. Wes states, "It's all won or lost in the bass." If you gap your speakers from the wall like shown in this video, you get a huge hole in the bass, as I've demonstrated in this video. "You can buy your Focals or whatever, but you’ll just be guessing with your bass! You can move them around for years, but you’ll just create a new problem" So he is in full agreement with what I've presented in this video. Bass frequency response is one of the highest priorities in room setup. And this final quote from Wes sums it up and puts this issue to bed, "You would always put speakers against wall unless you have a very deep room! 9-10 feet from the wall in a 30 ft deep room, otherwise no."

[@harrispappas6292]

omg!!! What a great video !! Well done and thanks!

[@warpacademy]

Our pleasure!

[@harrispappas6292]

It's crazy, a bunch of my questions were covered! I just changed my old monitor speakers to a threeway Eve sc3070 monitor system and i wanted to make sure with measurements etc how to get the best sound efficiency in my room working with these monitors. Did a lot of research... and research created a lot of questions and then after two weeks this video pop up in my YT feed... and i did get my questions answered !!! Soooo big up to Warp !!! In a small room (treated thought) i got the best results when i placed my speakers as closes as it gets to the back wall. It's not as simple as it sounds but it's working and as soon as you understand what you are trying to achieve in a home studio situation it's a solid advice!🙂

[@warpacademy]

Right on. Yeah, you definitely get the best results by doing the research, doing the testing, and following the physics of sound with all the best practices they dictate. Glad you're getting good results. Cheers!

[@ashishlakhani3446]

Super useful video thank you mate!

[@warpacademy]

No problem 👍. Subscribe and stay in touch!

[@chris.sarkaus]

Good video, thanks for making this. I do have a question though. What are your thoughts on the rule of thirds? How does that compare to the other approach you're suggesting which is to place the speakers right next to the wall? Thanks!

[@warpacademy]

Hi Chris. Thanks for the comment. I think you're talking about the 38% rule yeah? Arqen answers this better than I could. Please see this: arqen.com/acoustics-101/room-setup-speaker-placement/ And this: arqen.com/acoustics-101/speaker-placement-boundary-interference/ Cheers!

[@thebr0wnhornet]

I’m about to go move my speakers. Recently got stands and a smaller desk and doing testing last week had this exact dip. However the frequency of the biggest dip directly corresponds to one of my room modes so I thought that was the problem and I was about to build more bass traps. Maybe this is it.

[@warpacademy]

Hey hey. Building more absorption into your room is probably a good idea regardless as most rooms are seriously under-treated. The more absorption you have, the more you're going to damp room modes and the more you will widen the Q of your modes - improving the overall sound of the room. Hard to know for sure without knowing about your room. If you want to share info on your room and get more detailed tips, join our free Discord Server ➤ discord.gg/ZwNgZteGKw and post in the acoustics-forum. You can test to see if it's likely a room mode by moving your listening (mic testing) position forwards and backwards on the room's line of symmetry. If it's a boundary reflection causing SBIR, the null will remain at the same frequency because it's related to the distance between the speaker and the wall which is fixed. If you move forwards and backwards on the line of symmetry in the room, and you notice that the dip is changing to flat and then a peak, then that indicates you're moving from a pressure node to an anti-node in a standing wave (room mode). But, this could also be back-wall reflection interaction causing destructive and constructive interference too. When your distance relative to the direct source and reflected source change, you will change the frequency of the interference. Are you using a room mode calculator to figure out your modal distribution?

[@thebr0wnhornet]

@@warpacademy thanks for the detailed reply. Of course, I could probably use more trapping money is tight and it’s already pretty good, bass response improved greatly by moving my monitors to stands and off the top shelf of the desk, everything seems to be within 4db of flat. But in the problem area it’s -4 at 82Hz and +4 at 115Hz so I’m trying to flatten that out. Also, when I have the sub off it’s flat at 82Hz and a dip appears around 60Hz. As I’m typing this it makes it seem less like a mode bc if the mic was in a low pressure spot that probably wouldn’t change by adding/subtracting the sub- is that sound logic? I’m using REQ wizard for the testing and to calculate modes just did a quick and dirty 1130/room dimension but confirmed in the req room sim. Going to try moving the mic as you suggested before moving all my furniture. thanks again for the advice!

[@warpacademy]

Hey hey. If you have tests in REW, please post them. I need to see your actual results. You can send the .mdat file, or you can screenshot showing the All SPL / Frequency Response full range (20 - 20,000 Hz), and then the waterfall showing 1,000 ms time range, and a 60 dB SPL range from 5 dB above peak level.

[@GuidoGaule]

Great video, thank you for taking the time to explain all this. Love all your videos

[@warpacademy]

My pleasure!

[@flexiland6741]

Thanks for helping to dispel the tired audiophile myth about "correct" speaker distance to the rear wall.

[@warpacademy]

Happy to. As Wes Lachot says “everything is won or lost in the bass”. If you don’t get that right (or hear that right) you get a bad foundation.

[@faithtonejason]

Very informative! Great job! But I still got a question. When you flush mounted the speakers, did you put more bass traps in the front wall around the speakers? If so, wouldn't it be absorbing all the reflected bass frequency that could've boosted the low end? Or you just simply didn't bass trap the front wall and filled it with normal broadband absorbers?

[@warpacademy]

Very good question. Behind the front wall is basically an open cavity. In general, in acoustics, you usually damp any open cavity to tame up any resonance associated with it. We've use rock wool in the cavity. However, the bass performance is still increased as there is no rear radiation of bass. Because we've positioned the monitor baffle flush with the front wall, this extends the baffle. The speaker is now radiating into "half-space", which means any bass energy that would have been radiated rearward is now concentrated only in the half-space in front of the speaker baffle. This can theoretically produce a +6 dB LF effect. However in reality it's usually more like +3 dB. Similarly, placing a monitor in a corner forces it to radiate into quarter-space, which will have an even larger bass lift effect, although not usually desirable. Bass lift in a corner can be theoretically +9 dB, but practically more like +6 dB. Boundaries are not perfectly reflective, wall assemblies have low frequency resonances that act a resonant panel absorbers in the LF range, and there is some transmission loss.

[@pdm67]

This is a very well explained video, super helpful.

[@warpacademy]

Glad it was helpful!

[@lacrymoboy]

Thanks ! Another super great video : clear, valuable & easy to understand. I feel less stupid today, thank you :-). I hope you will shoot another one about "where I should put this damned sub !!!".

[@warpacademy]

You're most welcome. Thanks for taking the time to go through this deep dive and to invest in your knowledge. Learning this stuff is so key when you're a musician or engineer trying to get the best sound out of your equipment. Your question about the sub is a really good one. I definitely plan on shooting a video on that. I have a test room where I'll be showing how to build the best DIY acoustic treatment, how to position it in the room, and how to optimize a monitoring setup using Tannoy Reveal 8s and a 10" Genelec 7060B sub. I'll show all the acoustic testing along the way.

[@lacrymoboy]

@@warpacademy Yeah ! I can't wait. Thank again to take time for us. Now : let's move some stuff 🙂

[@warpacademy]

You're most welcome. Happy music making!

[@TheGreatConstantini]

Great video. Unfortunately, the software used is a bit pricey so I am going to try measurements with Room EQ Wizard. My Adam A series monitors can be adjusted via Ethernet and their software for any individual problematic frequencies as well as other parameters caused by the room.

[@warpacademy]

REW is great! I also use that for room testing. Can't argue with free. And if you can get over the learning curve with it, and know about proper mic placement / alignment, then you will be all good. Most professional acousticians use REW even if they'll end up using Sonarworks for the calibration and EQ stage.

[@TheGreatConstantini]

@@warpacademy Well I’ve used other software and understand mic placement etc. I just keep hearing about the learning curve from multiple people and hope I’m up for the task. My room is impossibly difficult but hopefully next year I will be building a more desirable room. I am building an approx 30’x30’ room with 9’ ceilings. And will be mounting my monitors in the wall. Moving the position to the center of the room would also be an option possibly being the way I work is in the control room for everything. Sort of tracking, overdubs etc in the round. We will see then as I make measurements.

[@warpacademy]

Hey hey. Thanks for the comment. I would highly recommend that you consult a studio designer or read some acoustics books (like Recording Studio Design or Rod Gervais book). Those dimensions for a room will produce really bad acoustics results. You never want a square room as your front-back and lateral axial room modes will stack. And a 9' ceiling height is way too low. You want 12' if you can. 10' is really squeezing it. If you have the luxury of a ground-up build, put in the research first so you build it right. Cheers!

[@dawn-moon]

Translating this to living room speaker placement, I guess the same placement advice applies to small bookshelf speakers ? ... but what about full range towers that reach to 25-30Hz ?

[@warpacademy]

Hey hey. There's an important physics principle to get here. It's about the size of the driver relative to the size of the wavelength it's producing. If the driver is larger than the wavelength of the frequency, it will be more directional. For example, with these speakers kzbin.info/www/bejne/r6vSoYCHd9GHkLs. Their single driver is 5". A 5" wavelength corresponds to 2,720 Hz. At that frequency and above it, the speaker will be progressively more directional. Anything below that will be progressively less directional and eventually omnidirectional. With smaller bookshelf speakers, assuming they're full range, the driver producing the LF will be very small relative to the wavelength of the frequencies they'll be producing. 60 Hz is about 19 feet long. So that means that not only the LF will be omnidirectional, but the low mids will also be radiating spherically. So with small satellite style speakers, it's much better to have them highpassed with a sub handling bass management. Full range towers reaching down to 25-30 Hz will absolutely benefit from being right up against the wall. But remember, you will get front wall loading, which will broadly increase the LF and you will need to apply a low shelf EQ to attenuate that if you don't like the bass-lifted signal. Some people may find the bass lift pleasing as our ears are much less sensitive to bass in general and we need more bass to sound balanced, psychoacoustically. This is why Equal Loudness Contours exist. Hope that helps. Thanks for watching and commenting. Subscribe to the channel and stay in touch!

[@VintiqueSound]

Great video! Lot's of useful information for optimizing results :)

[@warpacademy]

Glad it was helpful!

[@greyson66]

Hi thanks for the video! What if my front is window & I have -10db dip at 85 Hz, do I need to put acoustic panels behind my studio monitors or any solution?

[@warpacademy]

Glad you enjoyed the video. Acoustics is a science. To set some good expectations, no acoustician could ever assess your room from a comment on social media. Room analysis requires dimensions, photos, information about monitor placement, monitor type and frequency response, and much more. It's involved. If you want a quality (and correct) answer, you should hire someone. I am available for consulting if you'd like to work with me in that capacity. You can inquire through the Warp Academy contact form on our site and I'd be happy to help. Regarding your question about placing acoustic panels behind your monitors, I have a deep dive video on porous absorption and its capabilities here: kzbin.info/www/bejne/iYTRaXt7qKxrqNE. Watch this video and you'll quickly learn that acoustic panels cannot simply be placed behind monitors to solve a bass dip issue. It's more complex and will require a room analysis, including a modal analysis and room testing with REW. All the best!

[@greyson66]

@@warpacademy I have move my studio monitor close to the window/curtain. Now the 85 Hz dip is -4db but I got a huge boost on 50 Hz, 6db increased

[@warpacademy]

That’s low frequency boundary loading most likely from in phase constructive interference. You can EQ that to reduce it.

[@ILoveTeles]

I’d love a video on the role of ceiling corner traps and what they typically address (assuming near-wall placement and basic acoustic treatment: vertical corner traps and first reflection on side and cloud).

[@warpacademy]

Thanks for the suggestion. I'll keep that in mind. Cheers!

[@visualdreamtrap1931]

thx for all this good research. very well explained

[@warpacademy]

Glad it was helpful!

[@dessiplaer]

Good info, thanks for posting this video!

[@warpacademy]

My pleasure. Cheers!

[@lunevenus]

Thks a lot !!!

[@warpacademy]

My pleasure. Happy music making!

[@konjstip6156]

Great and informative stuff for anyone trying to do acoustic treatment ! This is going to be a longer post... I don't know if anybody said already, I would just like to add, I think in the first situation is as well rather front wall SBIR than the floor dip, or it can be a combination of both. EDIT: Oh, you explained it @09:54... In my experience the same applies for the situation no1... And the 1/4 wavelength is counted from the front of the baffle, it appeared almost precisely down to single Hz always in my measurements... I am saying this because I am facing a similar problem in our studio. I was trying to decide should we flush mount the speakers or not...We have a pair of 2-way 8'' studio monitors that are 30cm deep, they behaved really great in the same situation like yours (the whole studio heavily treated except the front wall). Right against the front wall (with like 10cm clearance behind them for the cables etc...) they shown exceptional low end like +/-3 db unsmoothed from like 40 to ~200hz where a sharp dip occurred... I slapped a layer of 10cm OC703 style rockwoll on the frontwall the dip disappeared, the measurements were +/-3db up to 300hz unsmoothed and I called it a day, I was afraid to do flush mount because I wasn't sure that we could make an appropriate cooling space for the amps inside the monitors, and the solution I came up with was too complicated for DIY... However for some reason while building the frontwall treatment, my construction friends got a little bit further inside the room with the slats construction on top of the rockwoll, making it now 15cm instead of 10... So 15cm + 30cm (speaker depth) + 10cm (cable clearance) 55cm in total which is a 1/4 wavelength of ~160hz now and the dip occured exactly there now... The "OC703" layer still catches it, but instead the previously +/- 3db response, it got slightly worse, like +/- 5db unsmoothed... Still good, but it was better before... And the real SBIR galore happened when we got a similar pair of speakers like yours which are 45cm deep, same as yours KH420... Now, 15cm (treatment) + 45cm (speaker depth) + 10cm (cable clearance) brought the SBIR null down to ~125hz and the 10cm treatment on the front wall can't handle it... The null is 10db down making the low end completely fluffy and weak... And now the only solution is to flush mount it, or build additional thick absorption around them, as you shown @22:16 as an alternative to flush mount... Putting any treatment behind such a deep speaker is just pushing the SBIR lower, really the only solution is some kind of flush mount... However if there wasn't the frontwall treatment the total distance between the front wall and the woofer would be 45cm (speaker depth) + 10cm (cable clearance) making it 55cm which is exactly 1/4 wavelength of 160hz as shown @04:20. I am curious, after you finished the studio and finish the flush mount construction did this 160hz dip persisted ? Also, did you take out the amps from KH420s or did you a make some kind of ventilation path behind them ? Can't wait to see your final measurements of the finished studio, I hope you are still going to publish it. Greetings

[@warpacademy]

Hey mate. Really good analysis of the video. It sounds like you have a solid understanding of the acoustics in this situation. A couple of responses: 1) My distance to the front baffle from the wall is different from yours, so the calculations don't apply exactly. I thought 10cm for cable clearance was unnecessary, as the speakers were toed in 30 degrees, which allowed for ample cable clearance in my case while the back edge of the cabinet was nearly in contact with the wall. Slight gap. 2) I did not find it necessary to use the amp relocation kits for the KH420s. In practice they are not generating sufficient heat behind the hard front wall for it to be an issue. We also have a Panasonic ERV unit handling ventilation for the hermetically sealed control room. 3) Final measurements TBA soon. We just finished construction of the custom mixing console and it will need to be disassembled and moved out of the room first before we can run final clean room acoustic tests. Then I'll shoot the room again with the desk in place. I'll be posting results for sure. Good luck with your room! Depending on the dims, flush mount could be a good option.

[@konjstip6156]

@@warpacademy Hi ! Well I said 10cm because the XLR itself is at least 5cm , plus toeing in also bring the outer edge of the woofer forward a bit, at least one cm or two... but let's say it is just the speaker depth 45+ 5cm... Still brings the reflection to ~171... close enough... Cheers, I'm looking forward to your final video about the room, and I'll follow the other stuff you put out.

[@warpacademy]

Cheers!

[@timchristiansen1287]

Dude.. Thank you for an in depth explanation and showing examples!

[@warpacademy]

My pleasure!

[@timchristiansen1287]

​@@warpacademyCan I ask where you would put your speakers and listening position in an equally square room. I have tons of absorbers, in corners, walls and ceiling. The room is 4 metres each wall. I feel like I have to sit in the middle of the room, so I will be sitting in a spot with bass completely out of phase.

[@warpacademy]

Hey Tim. Yeah square rooms are always a tough one, and small square rooms are the worst. That said, there is hope. Especially considering you've damped the modes with that acoustic treatment. Look at the recommended listening distance for your speakers, then place them at the minimum distance apart. It may be something like 1-1.5 meters for nearfields. Place them right up against your front wall, like I show in the video, and that will get your mix pos as close to the front wall as possible. You shrink your equilateral triangle as much as possible, then place the whole thing right on your wall. If you can be away from the center of the room as much as possible it will help.

[@anonymousbrowser4448]

Do you have any tips for doing that alongside a sub as well? Would you test them separately? I am planning on using Neumann’s MA1 for the eq, hopefully they can correct what you said and are linear phase

[@warpacademy]

Hey hey. Adding a sub to the system will make tuning much more complex if it's by ear, but the MA1 system will make phase alignment very straightforward so that's good. Use of linear phase EQ in room EQ is of questionable benefit IMO. Mixed phase may give better results. IMO if you're doing anything other than bell attenuation in the LF, or broad spectral tilts, then you're potentially causing more harm than good. The acoustics of the room determine how helpful EQ will be. In the MA1 here are my tips: Do not allow it to "correct" any nulls by adding boosts. Like the Sonarworks system, it's not capable of addressing boundary nulling from SBIR. Restrict its correction so that it's only permitted to do subtractive bell EQ below 300-500 Hz to reduce the effect of constructive interference from boundary reflections and modal resonances. Then add any broad spectral tilts you desire using the house / custom curve. Bob Katz's personal preference for a "flat target" for a control room is flat from 20 Hz to 1 kHz and then a linear slope from 1 kHz to 20 kHz with 20 kHz being 7 dB down from 1 kHz. Then in many studios, engineers prefer a low shelf boost of 2 or 3 dB below 100 Hz, but otherwise Bob Katz pretty much got it right. It obviously depends on how the room is treated and the directivity of the HF drivers. If the room is less extensively treated and the HF drivers throw lots of energy out wide, then there will be more HF room gain.

[@arijevacgaming921]

Hi there Sir! This is great video that helped me a lot, but i have few questions that you kinda already answered but i need to confirm sry. :) So in a typical bedroom, 3,5meters l ,3.35meters w ,2.5meters h, i would place my speakers between 2 walls, and not between wall and window side, and speakers should be very close to the back for the best results right ? :) And i have a question how would objects in the room like bed, storage thing and couch affect the frequency response :/

[@warpacademy]

Hey hey. Glad you liked the video. For more detailed questions about studio design and room setup join our free Discord server and post your question in the Acoustics forum: discord.gg/ZwNgZteGKw

[@andy_william17]

This video is by far the best video explaining speaker placement. Answered most of my curiosity. May i ask whats your opinion on wall mounting speakers using shelving or brackets, combined with decoupler stands?

[@warpacademy]

Hey Andy. Thanks for the comment. Glad you liked this one. I think wall mounted speakers can be quite difficult to decouple. Usually you need mass, and then spring. The metal wall stands don't have a lot of mass I think. And I'm not sure about the quality of decoupling systems that can attach to them. But perhaps there are good solutions? Are you looking at some particular make and model of speakers and stands? What's the application and use case?

[@andy_william17]

@@warpacademy thanks for the fast reply too! I was thinking about making a solid steel shelving first and on top use the isoacoustic aperta series to work as a decoupler. I got this idea while thinking about clearing some valuable floor space 😂 plus this video made me curious if the idea is plausible or not 🤣

[@andy_william17]

@@warpacademy oh and i am using a yamaha HS8, and its just for a bedroom studio. I am a guitarist and i am setting my room so that when i tweak my pedalboard, the tone i set can be taken on stage as well, with less or no tweaking needed to be done again.

[@warpacademy]

Hey Andy. Thanks for the clarification. I'd be very cautious of this. The reasoning is this. Vibration is very likely to travel into your stand, even with that decoupler. Decouplers like that only reduce, they don't eliminate structurebourne transmission. Usually with a speaker stand, there is a second decoupling system as it meets the floor, and then the floor usually has some spring to it with carpet or hardwood flooring underlayment. With a wall, you'd need to drill your stands directly into framing studs to get enough supporting leverage. As soon as you transmit sound energy directly into a stud, you have huge problems. Unless your room has been purpose built as a studio with a staggered stud wall, or double stud walls that are fully decoupled, then that stud will directly attach to your walls top and bottom plates. It'll likely transmit significant energy into the entire wall assembly, the drywall that's screwed to it, and then into the ceiling and floor joists. This can cause significant issues with structurebourne sound transmission to neighbours, but it can also cause your walls to transmit sound back into the room. Although stands take up some space, I would lean that way vs. wall mounting, unless the room was built to decouple the wall assembly from the drywall (with resilient channel or Green Glue for constrained layer damping) or to decouple the wall assembly from the floor and ceiling.

[@warpacademy]

My comments are more oriented towards a setup for a room used for mixing and mastering. If all you need is a jamming space, and you don't worry as much about acoustics, then wall mounted speakers may fine. They'll just likely compromise the acoustics in the room a bit, and exacerbate sound transmission into the structure of the building.

[@a_t_f2869]

@warp….. Adam’s or Neumann speaks? Looking kh80 vs the av4 ?

[@warpacademy]

Neumann all the way. The Adam XART accelerated ribbon tweeter design is so hyped and unnatural sounding. No one is going to be listening to the end result on that tech so don’t mix on it.

[@DomSchiavoni]

Please elaborate on Floor Bounce. I'm attempting to optimize a room with couple significant dips (155 & 190hz) that does not have a "console" to block the destructive waves. I assume many people will find their way to this video looking to improve their Listening rooms that also do not have a console that is typical in a studio. Great vid BTW! Confirms my recent studies on the matter.

[@warpacademy]

Hey Dom. Thanks for watching and commenting. Glad you found the video useful. While this video is primarily for music studios for critical listening and engineering, you could also block the floor bounce in a general listening room (like a hi-fi living room setup) by positioning a thick rug and coffee table in the reflection path. Although, for general listening, and not critical engineering of music, some floor bounce is generally acceptable to listeners. We're quite well adapted to hearing floor bounce as human beings. Cheers!

[@acreguy3156]

Great video. I was under the impression that nulls or low frequency dips caused by out of phase conditions, cannot be EQed upward because there's no sound there. You did this in the 2' away from the wall experiment.

[@warpacademy]

Thanks for watching. The nuance here is that Sonarworks adjusts phases and EQ. If it was a simple EQ then you couldn't do this. But with a digital adaptive EQ you can fill in that dip.

[@themattprofessor]

That doesn’t make sense. 1/4 wave SBIR cannot be equed out as acreguy says. All that happens is that the equed signal heads forwards and the same signal reflects off the wall and cancels, it makes no difference changing the phase either of what goes out of the speaker as the reflected sound will always be 180 out of phase with whatever is radiating from the speaker, so this null frequency remains, unless you can physically absorb the low frequency reflection. Eq can help to smooth out modal peaks and dips, but then they vary all over the room. It seems to me these speaker eq systems are best used to create a flat response speaker system, which ideally you would have to analyse in an anechoic chamber.

[@FOH3663]

Agreed It's boundary nulling, and it's undefeated. Perhaps some brute force absorption may help a bit, but any attempt to bring that level up just dumps more drive current into the voice coils, right? Physics issue, physics to address it. That said, I've not worked with Sonarworks.

[@themattprofessor]

I am prepared to be proved wrong! But from my knowledge of physical acoustics and wave propagation and DSP. SBIR cancellation is not something that can be dealt with by single speaker DSP equing whether by gain or by the use of all pass filters. There might be a solution involving perhaps a separate subdriver totally phase and level and timing controlled for a given speaker and room placement, to cancel the 1/4 wave or 180 degree cancellation. An EXTRA physical solution whether electronic or absorption is what is needed to deal with this problem.

[@warpacademy]

Hey hey. Yes, this is a very interesting part of the discussion. The Journal of the Audio Engineering Society has done this research. It's what Philip Newell is talking about in this book in the chapter, Loudspeakers in Rooms. Their research concluded that you can, indeed, fully correct the frequency response at a single position. If you want to see the results of their testing, look up the study I indicated on screen in JAES. It seems that they've been conclusive on this topic, but I remain curious too. That said, I haven't tested the after correction frequency response in my tests. So I've asked the technical team at Sonarworks for what they have to say on the matter. I'll reply back when I have more info :). Cheers!

[@wdkbeats]

Very good video! Looking forward for more on this topic. BTW - what about that 160Hz floor dip, how do you fix that?

[@warpacademy]

Glad you enjoyed it. The floor dip is addressed by placing the mixing desk in the reflection path and blocking / breaking it up. This is because it's not practical to have any acoustic treatment on the floor and carpet would do next to nothing for that frequency rance. My room will have a hardwood floor, partially for looks, and partially for function; the hardwood reflects some of the live scattering energy from the rear wall slats back at the mix pos. The ceiling is soft though, and will have extensive treatment plus a ceiling cloud. Thanks for watching and commenting!

[@wdkbeats]

@@warpacademy thanks! Will you explain it further in a video? That would be great!

[@warpacademy]

Sure. I'll likely do that when I get to the part of my room setup where I'm positioning the desk. Cheers.

[@federicovillora]

So, when we see a phase shift alongside the frequency response in programs like REW, does it mean that the exact drop in response is due to a reflection?

[@warpacademy]

If your speaker has a relatively flat anechoic response, which any professional studio monitor should, then any peaks and nulls in your frequency response are due to room reflections (which by their nature are out of phase to varying degrees and are dependent on frequency). You don't need to see the phase in REW to analyze this, you'll see it in just the All SPL window. Phase analysis in REW is not as relevant to this because even the direct signal from the monitor will have phase shifts due to the fact that every frequency has a different period and simply time of flight will change the phase relationships of frequencies relative to each other.

[@SkylarWilliams-ml3hs]

Wow this is the most informative video for acoustics and sonar works thanks

[@warpacademy]

Glad it was helpful!

[@Raymanuelmuzik]

Man what a gem!! Thank you. This helps so many

[@warpacademy]

Glad to help out!

[@bryanjones9952]

Nice video. I might be on the wrong channel for this question, but is this video only applicable to recording rooms or should a regular listening music/theater room also have the speakers as close as possible to the front wall?

[@warpacademy]

Oh that’s all good to ask here. If you have a bass managed system with a sub then this likely won’t be an issue for you as you can position the sub against the wall and the tops more freely. If the low end is also coming from the stereo mains and not a sub then you’ll benefit from putting them against the wall. But then you’ll want to shelve down the low end a bit to compensate for the front wall loading.

[@bryanjones9952]

@@warpacademy Cool! This is one of the few channels that suggests putting speakers close to the wall. Thanks for taking the time to reply.

[@warpacademy]

I think that’s because most people don’t take the time to understand the basic physics at work here. It’s not rocket science yet so many people get this wrong based on years of bad advice propagated on the internet that was never grounded in science or research.

[@emiliano9321]

Are you de-essing your audio, or is it just you and the mic placement? Sounds so good. Thanks for this video!

[@warpacademy]

Thanks. Which part are you talking about? In the beginning I was using a lav mic (I really don't like them, but use them when necessary) and further through I was using a boom arm mounted condenser. In both cases I'm using 2-3 de-essers throughout the post-processing chain. Glad it sounds good. Cheers!

[@emiliano9321]

​@@warpacademypretty seamless settings!

[@warpacademy]

@@emiliano9321 thanks!

[@BurgardRecords]

@ 4:18 What music is in the bg, I am always being a head hunter for those types of zen house tracks. Love the video!

[@warpacademy]

Thanks. It's a song from Epidemic Sound, that's the service I use for royalty free music for backgrounds. Not sure what the track name is.

[@dl6519]

GREAT video!! What happens to perceived soundstage depth with the monitors as close as possible to the front wall? Is there a degradation of the ability to perceive soundstage depth, and if so what can be done about it?

[@warpacademy]

Glad you liked it. No there’s no degradation of sound stage. Stereo field is primarily perceived in the mid and high freqs. So as long as you’ve done a good job with left right room symmetry and side reflection treatment you should be doing quite well. Depth in a mix has more to do with psychoacoustics, digital reverbs or recorded room ambience in the recording. Mixing techniques like EQ, delays and such will create your depth staging. Reflections off other boundaries in the room will mess with you more in terms of that stuff as they can smear transients and detail in the mix if you haven’t attenuated and controlled the reflections.

[@DomSchiavoni]

I think there may be a primitive misconception about sound stage depth relating to the fore&aft position of speakers. Three things i think this could have stemmed from are: 1. Recognizing the undesirable coloration of too much low freq boost with speakers up against the wall, and SBIR issues with speakers not far enough away from the wall. Both of which are eliminated by pulling the speakers out a third into the room. It dosnt take a frequency sweep to tell something is desirable or undesirable, but current day easy access to microphones, analysis software, and EQ/DSP provide a detailed picture of what is going on and how to optimize. 2. The visual impact of a room's setup can alter ones perception of the sound. Simply seeing speakers up against a wall signals you brain to think there is no sound beyond it. This is not an issue if you have the speakers behind a transparent screen or simply listen with your eyes closed. As a former musician i am minimally effected by this because i naturally see&hear the music and not the speakers however i can understand how some people with differing backgrounds that are more fixated on the "gear" could be swayed by this effect. 3. The speaker & room's impact on reverb. Sure, desired reverb(and similar spatial effects) should be in the track whether recorded or added in the mix/master, but if your listening to a poor track lacking these elements then having a room that 'adds' reverb could lead you to believe that your setup is bringing the song to life when in fact the track was dead to begin with.

[@warpacademy]

Hey Dom. Thanks for sharing your opinions. Thinking that you can "solve SBIR" by moving speakers into the room is incorrect and stems from old school, outdated HIFI recommendations. If you actually test a room as I did, you will clearly see that anytime you move speakers into the room on stands, you get substantial SBIR. The only way to address this is to move them so far into the room (IE 4 meters or more) that the cancellation dip moves below the audible threshold. BUT, who would do that? Who has 4 meters of room to work with? And where would that place you in terms of a listening position? The physics are basic here. As are the tests you need to run to demonstrate this effect. I'm willing to be proven wrong here though. If you have a room with speakers moved part way into it, shoot the room with REW and show me the results. If you get a flat frequency response (without use of EQ) I will eat my words. But I've tested this enough to know how it goes. In literally every acoustic test I've run in any room, this boundary nulling effect is present. You can't change the physics. Having a barrier behind the speaker will still reflect sound, no matter how far away it is, and having it just a few feet or meters away does very little to the strength of the reflection. The thinking that moving a speaker a short distance away from a wall (or a third into the room) somehow addresses the reflection is flawed logic and doesn't take into account how sound actually works.

[@GiuseppeLagetto]

Man brilliant analysis!!!!

[@warpacademy]

Thanks!

[@jeffsalvatore7441]

My issue is that im using a sub. I have to make sure the speakers and sub are aligned so that they're in phase. Is it better to put the sub close to the front wall as well?

[@warpacademy]

Hey Jeff. Having a sub is actually advantageous. You can (and should ) put your sub directly against the boundary, yes. That'll ensure you have a close to in-phase wall reflection that will add LF amplitude to the sub and allow it to operate more efficiently. Given that a lot of subs cross over at 80-120 Hz, you may still get boundary nulling with your tops, so it's also good to place them against the wall. Then for phase alignment, you have several tools at your disposal: 1) Manual phase alignment. You can use the tools on the back of the sub (phase switch) to roughly adjust phase. Then you can slide the sub to the left and right physically to fine tune phase. 2) You can use an automatic phase alignment system that's software or hardware based (Trinnov). Either way, it's pretty straightforward to tune the system. Make sure you're running tests all along the way with Room EQ Wizard or another room testing app.

[@VDJ4500]

A very nice, helpful video, however - i would never put anything fiberglass related that is not behind a non-porous material into my living/working space. I'm not gonna go into details, just to say there is a ton of safe materials with the similar acoustic properties such as recycled cotton etc. There is this myth that fiberglass in acoustic panels is safe, but in a year 2024 we have many safe alternatives, why to take chances that sound waves pressure will push some of the micro glass elements into the air and into your lungs? There is a reason why a fiberglass is strictly used behind the walls and it is covered with non-porous material (contrary to a porous, acoustic fabric).. just my opinion.

[@warpacademy]

Hey hey. I said this is a partially complete build. The insulation is only exposed because the room is not complete and I wanted to run this test before moving ahead. All of the insulation has been wrapped carefully in not one but two layers of fabric (cotton batting and Duvaltex / Guilford of Maine). There is zero possibility of fibers floating around. And when handling the material I use safety glasses, gloves, long sleeved clothing etc. Also the myth is actually that rockwool and fiberglass are unsafe. Read through the Myths section of the book Home Recording Studio by Rod Gervais. He’s an enginner and professional studio builder. He proved this point and went over all the studies in detail proving how fiberglass and rockwool (when handled correctly per the MDS) are perfectly safe. Recycled denim is great too. It’s also way more expensive. And unless you’re a total cowboy and handle fiberglass without any PPE it’s no more “safe”. Why is it that you think sound could create micro fibers the escape acoustic fabric? Do you have any research you’re basing that on or is that just an opinion?

[@warpacademy]

Here is a video showing the completed room with all the modules wrapped: kzbin.info/www/bejne/jpeykJWqecqLoMUsi=CIay_hXsHTcm1jgk Here is a video on exactly how I build these modules: kzbin.info/www/bejne/e3TEq3qwqtmejJosi=HoCoj00SAqv74Mon This is how they are wrapped: kzbin.info/www/bejne/hIrIqGiQpqyAbbMsi=ExpCjYkbbSBJpw9B