FAQ's Expert Guide to: Bass Management, featuring acoustics expert, Anthony Grimani

[@gregkramer5588]

I am glad I found this video! I am building a 14'x19 listening room in a basement. This will help. I am an EE by trade and understand all the basics and am ready for trial and error. Multiple subs is fine for me.

[@faqnatics]

Appreciate the support. Hope you liked and subscribed because I've got a lot of content coming out, and in addition to HT, I am working on a lighting design 10-part course to walk through what to put into each room of a house. Feel free to post any additional general questions as they come up in your builds. The main takeaways are: 1. Focus on the room and acoustic design first and foremost. I can make a good pair of speakers sound great, and a great pair of speakers sound bad, just by changing the position and room acoustics. People love to put bigger speakers and bigger screens because it's easy to see those gains, even if mostly visual/aesthetic. There is nothing wrong with that, but a well designed, treated, and calibrated room means that anything you put in it will sound great. As I get ready to build my personal theater, I will send far more time doing this, than picking speakers. For speakers/subs I want something that has enough SPL to hit reference and pressurize the room, and be accurate, and have as wide of a horizontal dispersion as possible, so it's accurate seat to seat. There are plenty of good products that hit this requirement, and in my case I plan to swap speakers more for reviews and testing, so having a good sounding and quiet room is the place to start. It always sucks to put money into another layer of wall, or acoustic clips nobody will see, but that's the science that actually means the most. Good luck on the room, FAQnatics is here to support where we can. ; )

[@ChadAV69]

Anthony should prepare a presentation for your average open concept room. Bass does not behave the same way in an entirely open room as it does in a closed up rectangular room. It takes more trial and error to find good seating positions and I wish Anthony would talk about his process on that.

[@faqnatics]

Agreed. I am going to be building an open room demo and a dedicated theater demo, and plan to go through the various tools for calibrating when the left side is 50ft, and the right is 10ft. If you haven't, be sure to subscribe so you don't miss it.

[@joelgonzalez8289]

I agree...I've watched his videos along with those on audioholics among others to piece together on how to treat open concept theaters. I have a 25x25 gameroom/theater with a hallway and staircase. Decay time was well over 675ms. Brought it down to 425. Hopefully he can make a video that helps those of us who don't have dedicated rooms.

[@faqnatics]

Wow, great job on bringing down the decay. I agree, as much as we all love the idea of theaters, media rooms are more common, and deserve some attention, as they are the hardest to get right, since they have so many inherent issues that can't be corrected by a sealed room... I am working on some lighting courses at the moment, but I've got both a media room (10ft coffered ceiling, open to the left, glass in the back, and a bunch of other things to content with) and a dedicated room I'll be discussing as I build it out. Be sure to subscribe please so you don't miss it. I'm about to cross 100 subscribers!

[@joelgonzalez8289]

Thank you...looking forward to future videos. Subscribed.

[@faqnatics]

Appreciate it Joel.

[@crazydwarfer]

As Todd Welti preaches 4 subs in the corners, or in the middle of each wall :) Awesome video. Always a joy to listen to Anthony Grimany. Too bad no-one is answering to emails on the website.

[@crazydwarfer]

Murphys's Law of Harmonics - LOL

[@faqnatics]

I'm happy to try and get a note over to Anthony or Trevor. Feel free to email me at [e-mail] if I can help.

[@faqnatics]

@@crazydwarfer I've been in enough rooms and heard the bass differences, that it seems to be Murphy's Law applicable!

[@martinlindberg1983]

Thanks Anthony for sharing your knowledge! It is "easy" to reduce a standing wave if you consider ONE axial, like length wise, but if you put all dimensions to play it will be VERY complex to understand what you are doing... I have been struggling for years with 2 x 15" in every corner (4 subs) using REW and MiniDsp 2x4HD in my HiFi setup. It is sure fun, but very complex and time consuming. The hardest part (for me) is time alignment with the mains, because they are not able to time align. Just saying :) Cheers!

[@faqnatics]

Agreed, which is why there are calibrators traveling all over the world. Enjoy the process, but if you ever want to get a calibrator in, or try to remote in, let me know and happy to find you someone that works with your theater and budget. Appreciate the comment.

[@fredygump5578]

Don't guess! The easiest way to set delays in REW is to use the "Time Alignment" tool (All SPL tab). It displays the effect of adding a delay in real time. I pick 2 subs, find a delay that improves response, then measure them together. Then I adjust delay between the combined measurement and the 3rd sub...repeat for the 4th if you have one. Try different combinations of subs to see what works the best. It'd be nice if REW let you "align" 4 measurements at the same time, but alas...

[@faqnatics]

Thanks for the comments @fredy, although I wasn't sure what the guess comment specifically referred to. I'll bring up the idea to REW. Not sure they will add it soon, but with more and more information coming out on multiple subs, it would be a good addition.

[@fredygump5578]

​@@faqnatics I was reacting to when he said something like, "add a delay of like 2 seconds and see if it helps." So he was saying use the "guess and check" method. My point is REW has a tool that removes most of the guesswork!

[@dylanwright5837]

​This tool came in an update and totally changed the way I use rew for live events! They recently added the impulse comparison window that added a ton of great utility ​@@fredygump5578

[@scott-richardson]

Just received two more subs to add to my existing one. I have placed the two new ones on the back wall, off the corner a little. My front sub is between the left and centre speaker. I can immediately tell the sound has improved and filled the null I had at my main seat at 35-50Hz. Later today I will calibrate MiniDSP with REW and time align and gain match, EQ etc...

[@faqnatics]

@@scott-richardson sounds like a solid improvement. I have a feeling I’ll be doing the same in my media room build. I’ve got two subs that will go in the front, and gonna see what Dirac Art can do for the room first, but my seating is a bit further back since it’s in the family room, and it seems to be hitting a null. Luckily we can always add more, and wireless subs have come a long way in terms of processing speed, for those that can’t easily wire to the front and back.

[@scott-richardson]

@@faqnatics ah yeah the wiring is painful. My room is already all built so I have an electrician coming in tomorrow to tear the place apart. Got to rip up the carpet on my riser, and cut out some plaster board on the side wall so that we can run the RCA's from my MiniDSP and also some power to the rear of the room to connect the subs. Currently running long cables along the floor to do my initial testing. I'd love to have a 4th subwoofer to place at the opposite side on the front wall but that's where my components are currently so we will have to settle with 3 subs for now. I think I should be fine with 3 honestly.

[@faqnatics]

@@scott-richardson yeah, that sucks, but you’ll be happy with the results I’m sure. I’ve got to build a room within a room and fabric walls, with multiple layers of Sheetrock and absorption to try and keep the sound inside. Building it is half the fun though.

[@scott-richardson]

@@faqnatics room within a room would the ultimate. If I ever build again I’ll do that. I just finished running REW and I’m super happy. Basically flat from 10hz to 70hz in my room now. No low boosts just a few cuts and a little boost at 60hz null. Sounds ridiculous.

[@faqnatics]

Wow, that's stellar. Hoping to get something similar, although I'll have the added expense of building a room that can demo a minimum of two complete systems at once. Multiple processors, amps, speakers, and projectors. All in a truly blind A/B format. Should be interesting.

[@sagi_tech_n_stuff]

Great presentation!

[@faqnatics]

Thank you. I’ve got a bunch more content coming out this year, so please subscribe if you didn’t already.

[@MilGrip76]

Doctor Grimani innoculating the masses to better bass.

[@faqnatics]

As I build out my theater I plan to have a bunch more videos with various sound and engineering experts on to talk about the various technologies, acoustics, and sound pressure needs in a room to delve further into the topic in a fun way everyone can understand.

[@TokeBoisen]

Sometimes I enjoy your talks so much I forget you are absolutely not talking to people like me, primarily. Sure, the fundamentals don't change, but I realise the audience for most of what you do is people who can and are willing to put down money for SVS's flagships, or build and can accommodate subs the same size and performance. I appreciate Anthony's knowledge and he's an excellent educator and presenter, but I really have to remind myself that "not a lot of money" and "SVS's 16-inch subs" are not targets I can aim for

[@faqnatics]

I hear you, but there is always another system that's even bigger and better, so we just have to be happy with what we have, whatever the level. If we can enjoy our favorite movies, TV and concerts on it, it's a great system. I think the main thing at whatever budget you're at, is to work on the fundamentals. Acoustic panels, bass management, they are the same whether you're building a room within a room, or tossing up some home-made panels. Tools like REW are relatively inexpensive, and depending on the room size, two or four matching 10" subs might be enough SPL to pressurize the room and give you great quality bass down to around 20-30 Hz. Then add a larger sub for infrasonics down the line. The point is to enjoy the journey. I often see people in the threads hating on things they can't own. I like to look at it as aspirational, it's objectively the best of the best. and even if I can't afford a duplicate system, I can take the thought process and utilize it at my budget. I appreciate you giving it a watch and engaging.

[@TokeBoisen]

@@faqnatics, I absolutely agree that the fundamentals are solid, and applicable for scaled-down systems. Incidentally I am running four 10" subs, although mounted two-by-two in opposing corners, and I agree that the systems and targets Anthony lays out and uses as reference are aspirational. I simply meant to say that it's in my best interest to remember to keep some perspective on what is ideal and what I can actually do, so I don't end up feeling defeated that I don't reach the same targets

[@faqnatics]

I totally understand. I've been in some theaters that are likely the cost of my house, or at least some time between when I bought it and now! Rather than hate, I just look at it as aspirational, although before I personally spent that much, I'd likely buy another rental property or something else instead. But we all have our priorities, and anytime I can see a thing of beauty, be it art, car, bottle. theater, I always take the opportunity. Enjoy the day.

[@AussieTimeSirStewietheKnight]

This guy is a world of info

[@faqnatics]

Appreciated. I've got a bunch more content coming out in the next 60 days, so make sure you subscribe and get those notifications on, so you know when they drop. I've got bass management, theater design, and I'll be documenting and walking through four builds I'm working on for the next 3 months.

[@Bradimus1]

If I ever get to build a house, I actually want the theater room upstairs to have the wood floor to shake a bit and give me better bass impact without having to build a floating floor or use tactile transducers - and in wall everything with high quality speakers. If I can have 3-4 really good seats I think that's perfect.

[@faqnatics]

LOL, I love it. Agreed on the 3/4 seats. Mine will actually be above my garage, and will have 3 seats, a few bean bags up front, and a bar row in the back still far enough away from the back wall. Getting ready to design it now. Love the idea of a bit of flex in the floor. My only issue I have to deal with soon, is if sound bleeds out, it also bleeds in. In my case to the garage which means engine noise and the garage door noise which I can clearly hear at the moment in the room. However, there are ways to fix some of that, so I’ll be sure to play around with the various options to hopefully provide some insight for your room when you get there. Thanks for the watch and comment.

[@Bradimus1]

@@faqnatics you should get direct or belt drive openers. I have belt and they are extremely quiet. You don't hear the doors inside at all.

[@faqnatics]

I will likely update them to direct, although I think they are belt drive currently. The issue isn't so much the sound of the motor, it's the transfer vibration from the frame itself. That vibration can make a ton of noise coming up through the floor. I'll get it figured out, but I want to test piece by piece to see what steps reduce sound the most.

[@Oleksandr-Audioholic]

Hugely useful info. Thanks a lot. And how to calculate the perforation greed to make a riser as a bass trap?

[@faqnatics]

I am trying to find some previously released information on this topic I can post for you. I'll post anything I can find to help.

[@Oleksandr-Audioholic]

Thanks. I appreciate any advise on that

[@wells2671]

At what SPL are the sweeps being ran? I'm asking because it would help to know what is a peak and what is a dip in relation to the intended output. Fo example if the signal that was sent to the sub (at the 7:39 timestamp) was sent out at 75dB, then it would follow that the only 2 dips below the intended SPL are at 52Hz and roughly 104Hz. That's very different than if the signal was 93dB, which would make everything above 40Hz is losing energy. If the signal was sent out at 75dB you could probably EQ all of those peaks to flatten the response and possibly ad 2-3dB to the 52Hz and 104Hz dips to bring them up a bit if possible.

[@faqnatics]

I'll go through some of my notes and ask Anthony, but typically he would be running that signal at reference level with pink noise to properly calibrate it, so I don't think he'd be running it at 75Hz, but I'll see if I can get an answer.

[@wells2671]

@@faqnatics I'm guessing that you meant to write 75dB no Hz.

[@giovanni1269]

What is the effect of stacking two subs in one corner and does it have any benefit or will it be better to put them on the sides?

[@faqnatics]

Hey Giovanni, I'm guessing you mean if you only have two subs? If so, they should go in the middle of the front and back, or the two sides in order to help get rid of the standing waves from the modes. Stacking two subs on top would only really be beneficial in adding additional SPL in pressurizing the room, say you already had four and then went to eight, but first work getting to two or four subs, and with two, run them in the middle of the walls, and once you have four, put them in the corners to smooth out the bass overall, and pickup the additional power from the corner boundary reinforcement.

[@giovanni1269]

Thanks for the input and thanks for providing all of us enthusiasts with great information.

[@faqnatics]

@@giovanni1269 happy to help. I am finishing an edit on a discussion on the CEDIA booth, sound room 10, and it has a lot of great insights on room design as well. Be sure to check it out next week when it launches.

[@sickmessiah]

I have bass absorber ideas I’d like to ask if they have been done. Like.. I box with nothing but passive radiators filled with poly fill or Rockwool with a rear center port that’s adjustable tuning. ( pvc length ports ). Has that been done ?

[@faqnatics]

I don't know if having the port in the rear center is important to you, but here's a link to an Artnovian product that might work. It has plates on the front that allow you to adjust the frequency range you're trying to trap. kzbin.info/www/bejne/gHmrlZmnZcl0a9k If you want a more DIY setup, you can try this video I found on building your own. That way you can build it however you want. Typically it's the weight and tension on the membrane that's adjusting which frequencies are reflected, and which frequencies go in and are at least partially absorbed by the trap. Is that what you are thinking the port would do, or are you trying to use the port to amplify a certain frequency with the remaining energy output? kzbin.info/www/bejne/jaLRcmenpcaUhLM

[@CarlVanDoren61]

JLA cr-1 active crossover Simplifies everything 😊

[@faqnatics]

Yes, JL is great, although any system with DSP and multi-setup can do something similar. Grimani uses an active crossover or DSP in the amp which allows much more control than a passive crossover, or a simple 80/120hz switch. I’m playing around with Theory Audio’s new Dante enabled DSP in an open media room to see how it can help with the room as well. Adds a layer of complexity in that most general users buy an amp, but a pair of speakers and want it to work, but if you use an active crossover design it allows you to control the drop off and pickup levels of each speaker more precisely. Appreciate the time and comment.

[@matta9316]

What a great video!

[@faqnatics]

Thanks. If you haven't checked out the latest one where Anthony and I go through the design of the award-winning CEDIA Expo room we built, you can find it here: kzbin.info/www/bejne/mGmqoWR7f5qApac If you haven't please like and subscribe so I can keep getting out this great content I usually build for the trade side of the industry out for everyone.

[@Saturn2888]

Bass being omnidirectional means you can face your subwoofer in any direction right? I was hoping those measurements Grimani did would show what happens when you simply turn the subwoofer around. Heck, my subwoofers push down to the ground, and I guarantee that's bound to cause some difference. When I can see air moving out from the bottom of the subwoofer (for some really loud low bass testing), it's clear that's not going to sound the same as if it was facing me.

[@faqnatics]

@Saturn2888 I see this a lot, but you are combining two thought processes that I see happen a lot in the forums. Bass radiates in a sphere in all directions, which is what I think you are referring to. We will get to that in a moment. Omnidirectional though typically is used in comparison to the directionality of higher frequencies, and has more to do with the size of the wavelength, which is also what helps to impact the first point. Tweeter frequencies are the most directional, and the wavelength on these are measured in inches. That means that it will often hit one ear before the other, allowing you to localize the sound, ie. it's coming from the front left or rear right. Think of it like a snapping stick, we need to know where the sound is coming from, so our brain is honed in on understanding where the sound is coming from. Mid frequencies have a longer wavelength, measured in inches or feet, but we can still tell that it's coming from the speaker, or say between two speakers if properly imaged... This is also why on/off axis placement is so important, because that ability to localize and image where the sound is coming from, is what allows for the creation of stereo imaging. Those short waves are also more likely to bounce off of surfaces like a speaker, which is why they don't sound as loud when you move off-axis. When we get to bass frequencies, 80Hz or 40Hz, depending on the person, and room construction, the waves are 20' or longer. (At 40Hz it is about 28 feet long). That wave is so big, it is basically encompassing us, and our left ear says it hears it, but our right ear says "no it's over here. That's what is meant at omnidirectional, not that it goes in every direction, (which it does), but that it can't be localized, or it's really hard to know where the subwoofer is placed, if you can't see it. Now the commonly associated other meaning of omnidirectional, is that bass is going in all directions, so does it matter which direction the subwoofer is pointed in, towards, me to the floor, to the wall, etc. I watched a video the other day, and I know they were trying to show some power, but they put a bottle in front of two subs, and one was moving the bottle much more than the other. You know the classic "water bottle" test! But the reality is that he was placing it in front of a smaller round port on the one that moved more, vs. a slotted port on the other. So really it had nothing to do with the strength of the sub, but just that the air coming out of the port was more focused. No matter the direction of the sub, the amplifier power, sub excursion (how far it extends, 2"-4") and how many walls or boundaries are near it are what dictates the potential power of the sub. Having it facing the ground provides a super close boundary of the floor, and what you are seeing is the air going down and then being pushed right back because the floor is right there. A sub facing the wall does the same thing visually, and corner loading it, gives it the floor, plus the two side walls, because no matter which direction the sub is facing, the wave is immediately bouncing off those walls, possibly changing phase, getting absorbed, lots of stuff is happening that muddies it up a bit, but it is louder, which is why walls and corners produce more output than putting it 1/4 of the way in the room, at which point the wave doesn't have the immediate bounce off the walls to reinforce the actual sub excursion. Specifically to your question, every sub on the floor gets floor boundary reinforcement, it's just not as visibly noticeable as when a sub is pointing down, but it's also not as accurate when pointing down, just like adding ports and other methods of increasing sound at the cost of a bit of accuracy. Realistically though, the cone size, power, and room are all playing a part in the sound. Getting the sub into the right place, with proper absorption, and multiple subs to balance the waves, is what will get you the best results. Turning a sub towards a wall, or floor may create more bass, but it may be muddier, and ultimately the wave is still the same, which means louder at certain points, but is still going to have the same nulls in the room. Hope that helped a bit. It's long, but I hate answers that just say read this, or don't really answer the question. Let me know if I can clarify anything else, and if you haven't please like and subscribe so we can get this out to more people.

[@Saturn2888]

​@@faqnatics Thanks for your response! I get what you're saying now! That clarifies a lot of things! I'm curious to play bass sounds from different speakers to see if my kids can hear where those sounds are coming from in the room. I believe that it's hard to hear where bass comes from based on what you said, but I still think I can feel it; as in, I know which direction I got hit with bass because it will probably have noticably more pressure from one side than the other. It's something I wanna experiment with. I also wanna see at what frequency I can localize bass sounds. --- I didn't realize facing the sub in a different direction could get you more output nor did I know it would muddy the sound either. That's important information, but it's interesting it's not relevant to room modes. In terms of questions, let's say a sub points at the floor on carpet vs wood. Does that change the muddiness of the sound?

[@faqnatics]

I'm glad I could help clarify, and want to make sure I clarify a few of my comments as well. What I mean by changing the sound or muddiness is that by changing direction of the sub, or as you mentioned pointing it down towards hardwood vs. carpet, you are possibly changing the reflections in the room, which may be adding or removing from the power of the wave depending on any timing or phase changes those materials may affect. The mode itself is based on frequency and room dimensions, so I'm not saying that it adjusts the mode, but every boundary you put a sub close to, floor and walls, it typically increases the gain by about 3dB, although this changes a bit depending on level and frequency. Increasing the gain this way is accomplished through reflection, so the additional bass is accomplished at the cost of a bit of clarity or accuracy, which is why there is sometimes argument about what's okay. The amount of subs impacts this as well, since one sub in a corner may amplify any issues, where as four subs placed in the corners allows you to then DSP the issues to get a more equal response seat to seat. If you are going to listen to try to localize bass. Try at specific frequencies, rather than a track. An explosion may be considered low frequency but the reality is that it's a blend of frequencies, many of which can be localized. Of course you know where your subs are, so it's a bit of a biased test, but listening to how the sound changes location as you move down the frequency scale, should give you what you're looking for. Hope that helps. Are you in Eu or US as it's almost 12:30am for me. Enjoy the chat though. Hopefully I'm being clear, it's a bit late, and need to finish up a few things for work. Have a great morning.

[@Saturn2888]

@@faqnatics I'm in the US Central time :p.

[@CarlosGomez-THX_1138]

Thank you, sensei.

[@mikedinno8413]

What's your take on crossover for LFE Small vs Large speakers and double bass?

[@faqnatics]

Anthony talks about this a bit, but the idea is to cross over the speaker big or small at around 80Hz. That's because room modes are starting to take over at that point, not just whether the speakers can handle it. Adding more 40-80Hz coming from locations other than the four subs he discusses, can cause new standing wave issues. So let the four subs do their jobs, cross the LCR and surround speakers at 80Hz, and if you need more SPl for pressurization, use larger subs, or an infrasonic sub which can be placed a where and reach into your soul as far down as needed...

[@pulDag]

​@@faqnatics* Room modes

[@faqnatics]

Thanks, not sure if that was autocorrect, or just a slip of the finger.

[@FadriqueFM]

I built a room 3 years ago, I didn’t know much about anything but I put fiberglass sandwiched between the gypsum walls and the concrete walls (it’s a room within a room). It sounds good but I want better, and I was thinking about replacing the gypsum for fabric, but now I’m curious if it’s better going the way of using the rubber isolator instead? Any help is appreciated, thank you for the content.

[@faqnatics]

Hi. I’m in the middle of a project, but happy to discuss some best practices. Give me a day or so.

[@FadriqueFM]

@@faqnatics Thank you. 🙏

[@faqnatics]

So there are lots of ways to build a wall with some benefits, but the isolators allow for a better decoupling of the walls. While sound will obviously reflect off the gypsum, plenty of sound goes through it and the fiberglass and then bounces back off of the concrete behind it in your case. Moving to fabric, may change the sound a bit, but it's a larger expense, and isn't going to change much in the lid to lower frequencies. Here's a quick bullet on each of the things you mention: 1. isolator clips: These work great by decoupling the gypsum board from the studs. When you don't do this, the vibration tot eh gypsum transmits from the stud in your room to other rooms of the house. So while this can help with some wall flex and reducing additional vibration/noise from the studs shaking, it is often more for reducing unwanted noise in the other rooms of the house. It sounds like we are discussing quality inside, but is sound outside the HT room an issue? 2. Fabric walls: These are great, but are often designed to be aesthetic in higher end rooms. They remove acoustic panels and speakers from sight, which often people like to see. They can allow for a bit more control in acoustics, but many of your trouble frequencies in the mid and lower range are already passing through the gypsum and fiberglass, and reflecting off the concrete. Removing the gypsum for fabric, will only stop a bit of that absorption. 3. You mentioned a room within a room: This means different things to different people, so I just like to make sure I understand. Do you just mean that you just created a new gypsum wall with fiberglass in between, making the room smaller, and better. Or did you actually decouple to room by staggering studs, using floats for the studs, or other practices. I just ask because you mentioned the isolator clips, and that's often a tool used in a room within a room build, so just trying make sure I understand the build. 4. Rather than fabric, if the goal is to soundproof the room from the outside rooms, isolator clips, and actually adding a second layer of gypsum with a green glue or mass loaded vinyl in between would be helpful. This is what I'll be using in my personal theater build. I will actually have fabric to cover the walls, (with some surprises I'm not discussing yet), but then two sheets of gypsum, MLV, and acoustic material will be 6"-12" behind the wall, to enclose the speakers/subs, absorption and diffusion products, and anything else. While difficult, my goal is to limit the sound and vibration of this small theater room to the rest of the house, so that I can use the room without disrupting the rest of the house, as well as not letting the rest of the house disrupt me! Hope that help, happy to answer or clarify any additional comments.

[@FadriqueFM]

@@faqnatics Thanks for this very informative reply. So, In my ignorance I thought by exchanging gypsum for fabric I would improve the sound by eliminating some of the reflections, but if I understood you correctly that’s not possible because of the concrete walls behind it? And by room within I room I meant that there used to be a room with concrete walls and wooden ceiling, and I built my dedicated room with it, closing a small portion that used to be open and covering all with gypsum (the walls and ceiling), also carpeted the ceramic floors inside it, and built a riser (which also has fiberglass inside it). The sound is very contained to be honest, tho the subwoofer does make the wooden framing of the rest of the house’s ceilings rumble but doesn’t bother us really. So in my situation do you think I’m alright? Perhaps I could just add some acoustic panels here and there?

[@faqnatics]

@FadriqueFM,thanks for the detailed explanation. Based on what you are describing, removing the gypsum to add fabric is purely aesthetic, and while it could change the sound a bit (for better or worse) it's not really fixing anything. If the occasional rumble and sound aren't upsetting anyone outside of the room, I wouldn't worry about the soundproofing aspect, and if you want to improve the sound, start with a basic 15%-20% absorption panels in the room and 15%-20% dispersion. We discuss this a bit in another video on my page, where we show the award-winning build from CEDIA Expo. If you haven't watched that, give it a look, as we show some documentation from the room itself on what and where we put acoustic panels in the room. Enjoy your theater, and your FAQnatics family is always around to answer any questions, just not to borrow money, or watch the kids... ; )

[@KASmonkeys]

Thanks! So four subs in the quarter position but pointing in which direction pls? :)

[@faqnatics]

Typically aimed on the 90 degrees towards the center of the room, but because bass waves are pretty omnidirectional you are going to get a similar response in either direction. That's why when you put it in a corner, the wave starts growing, then moves down to the bottom of the wave, and then back up again. By bringing them in to a quarter of the way, the idea is that you remove two boundary reinforcements, which cleans it up, and makes it easier to get around the nulls, but at the expense of some bass SPL. Just to clarify though, while that is deemed to be "the best", Anthony's point is that if you put the subs closer to the corners, but still use four of them, you get the additional reflection "boundary reinforcement" of the walls, and any reflection issues can be removed or lessened via DSP, so the gain in bass, with four subs in the corners (facing into the room) is worth more than the potential issues it causes. Hope that clarifies it. There is another video, I think it's linked at the end on the CEDIA room he built with the StormAudio and Seymour team, and it goes into the room design even more. Here's a link: kzbin.info/www/bejne/mGmqoWR7f5qApac

[@KASmonkeys]

@@faqnatics Thanks so much! I'm just building my cinema room slowly so learning as much as I can before each step. I'm currently researching best ways to feel the bass! Will start with 2x SVS SB3000 disguised as coffee tables near the sofas for now on a concreate floor, whilst thinking of ways to get the vibrations up through the sofas while also not loose much height. Glad the vid mentioned them! 😀

[@faqnatics]

@@KASmonkeys happy to help. I’ll be adding a ton more content in the coming months, on theaters, media rooms, lighting, etc. Depending on your budget, there are definitely some better ways to go. Definitely watch the cinema design link I posted if you haven’t yet. Post if you have more questions, and appreciate if you like and subscribe if you didn’t already! 😉🥃

[@TrueStereo-]

I have four subs and can get better frequency results and room gain by changing time domain of subs. However in my case the timing is off from the front and other speakers. A drum does not sound good. What do you do to get the timing of the other speakers matching the four optimized subs?

[@faqnatics]

Hard to know without some testing of the room, equipment, tuning capabilities. etc. but in generics, you can try to delay the speakers to correlate with the subs, but then you risk a lip sync error with your video. Are you running Mini DSP, REW, or the processor's and sub's control for time domain in the subs? Do you have the room acoustically treated? This is where I'd start, since the thought is that 70-80% of what you hear is reflected sound, which means controlling those reflections becomes ultra important to an overall great sound. I'm assuming we're discussing at the MLP, but when you get into theaters vs. 2-channel audio where it is often a single listener, having a wider dispersion speaker becomes important as well. Any issues there, and you might be getting strong reflections that are impacting the sound and smearing the vocal as you mentioned with the drum. Feel free to list a bit more in terms of equipment, how you are measuring, and any acoustic treatments, so we have a bit more info. For a lot of us, the chase is the fun, but if you want it to just be right, I think no matter how much time you personally invest, bringing in a calibrator for audio and video is generally a big plus. They are able to look specifically at your room and equipment, and provide recommendations, and depending on the issue, they often have better measuring tools and knowledge to get it done and the ROI is huge vs. cost. I don't think I've seen anyone say they had a room calibrated and was disappointed in the results. Happy to bounce some ideas back and forth in here, and I can always recommend a few calibrators that are good and might be local. Appreciate the comment, and please like and subscribe so I can get more experts and content out to everyone!

[@welderfixer]

It's a major bummer that I am too F'ing old to work as an apprentice to Mr. Grimani. So much to learn and to apply. Dealing with my 2 two subs is like trying to teach a pair of uncooperative gorillas to play the drums.

[@faqnatics]

I hear you. I enjoy the time I've spent with him, as well as Matthew Poes who is int eh forums a lot answering questions. I've also been chatting recently with Paul McLean, who is out of Australia, but does some great work, and has some new announcements coming at or shortly after CEDIA. Ultimately, I want to make some deeper how-to's where I actually show active calibration of multiple subs in y room, including 1,2,3, and then 4 subs, to show the difference in room modes, and why it's important to overall sound. But that's a December-February endeavor, since I'll start on the room in October. I'm confident it will be the best and most easy to follow content out there though, it just takes more time to create.

[@welderfixer]

@@faqnatics Good luck with your adventure. Time consuming it sure will be.

[@CarlosGomez-THX_1138]

Put the sub at mlp run REW and move the mic around the room. But first gain match.

[@faqnatics]

This can work, although some acousticians have discounted the sub crawl a bit when you add more seats or a more complex build, and I like the idea of using a mic instead. Moving the sub on a dolly can be a bit easier than lifting a heavy sub onto a chair, plus the potential damage to the chair. Outside of that, the sub crawl works well for figuring out where the nulls aren't, but you might be listening to a signal out of phase, which starts to add more complexity as you add in the LCR and surround speakers, or especially when you start introducing additional subs. So I love the idea of the modified sub crawl, and it definitely has some benefits in making sure you don't stick your MLP in the middle of a null, but especially in a theater where you have more than one MLP (I need the spouse and kid to like the sound in their seats to keep getting budget allocation) tools like REW, Dirac, and multiple microphones dramatically help in getting every seat to sound their best. Appreciate the comment, and thanks for watching. Please like and subscribe so I can keep making more content.

[@CarlosGomez-THX_1138]

The room is only for me, my last calibration I kept the mic at the MLP and moved the subs around the various null points. I had help and put them on plastics slides.

[@audiononsense1611]

1. Go back and edit this so we all can see cursor better!!! 2. Thanks you so much for "Don't put a single Sub in a corner of a Gypsum construction home"! 3. Bass Traps, thanks again for that comment (They don't exist)!!!!!

[@faqnatics]

Thanks for taking the time to comment. Cursors will be highlighted more on my upcoming content.

[@mikemcguinness1304]

Why do you people always talk in terms of home theater?

[@faqnatics]

Hey Mike. Do you mean content home theater vs. 2-channel audio; or do you mean home theater vs. media room; or home theater vs. the dining room? If you could clarify the question a bit for me, I’d be happy to provide an answer.

[@mikemcguinness1304]

@faqnatics OK so I mean I wish you'd do more vids to do with 2 channel in terms of bass management. Thanks

[@faqnatics]

Fair enough. As I build out my room, I was planning to do a 2-channel version of it as well. Here's a few points though that I hope clears up some of what you're saying. 1. I'm generalizing of course, but 2-channel is often about the main listener position. People like to relax and unwind to some music, and that is often done alone, or with one other person. Setting up the room for 1-2 seats next to each other is "comparatively" simple vs. trying to get even sound pressure from seat to seat in a 6-10 person theater. Now we start adding in modes that you don't really care about if it's not where you're sitting in the 2-channel scenario. 2. For many 2-channel purists, there is a thought process that you shoudn't/don't need a subwoofer. This usually has to do with imaging, and is why some of the better/more famous 2-channel speakers are designed with much larger woofer drivers vs. their home theater counterpart. However, I think this school of thought is a bit simplified, since to the heart of your question, those subs in the 2-channel setup may be causing a null in your favorite spot, but you can't move it because the positioning of the speaker is required for imaging purposes in the mids and highs. Crossing over the speaker even in a 2-channel scenario is still therefore important depending of course on room size, acoustics,... However it really isn't a 2-channel system anymore, it's now a 2.1, with the .1 possibly being 2-4 subwoofers around you. 3. Depending a bit on the speaker itself, but in general, if it sounds right for home theater, it's probably going to sound amazing for 2-channel as well. I know that myself, Keith Yates, and Anthony all typically utilize 2-channel tracks in our demos, so it's not that we aren't teaching this in terms of 2-channel, it's just that we're often building the room for Atmos audio, movies, and 2-channel. A 2-channel system can sound amazing, as can a good 3.1 system for movies, but if you have the space, budget, and desire for the best experience out there, it's going to be more than 2-channels. That's not an argument against a great 2-channel system, but that system can only be used for 2-channel playback, everything else is downmixed to it, but a 7.1.4 is still perfectly setup for that prime listening position, sounds amazing for music, and can do so much more. 4. There are of course additional considerations if you are really at the high level of pristine audio. Speakers being placed in front of or behind a screen obviously reduces some of the sound power of the speakers, but again, great woven screens like @Seymour Screens help to alleviate this by reducing all sound across the major spectrum equally, so it becomes more of an issue of having a bit more headroom to turn it up, rather than the screen imparting major characteristics. I hope that clarifies a bit. Most of us enjoy music as much as movies, although there can be some digital vs. analog discussions between the two groups. But I do agree, it is nice to have one place to learn what you need, which is the idea behind FAQnatics. I'm not selling anything, I'm just taking the courses I typically build for Integrators and bringing them to consumers so they better understand what they need, and feel more confident in the science, when they go to a shop or are looking to upgrade their system, lighting, shades, whatever. So I'll make you a deal, you like and subscribe, and I will build you a training specifically on room acoustics and the benefits of adding subs for proper bass management for 2-channel audio! I'll need into the summer since I am just starting to design and spec the theater now, but I'll be documenting all the steps, and will happily build a video or two on 2-channel for those that want to build the best room possible. Thanks for the comments, I hope that was a good short-term/long-term answer for you.

[@mikemcguinness1304]

@@faqnatics yes great , I'm looking to add too subs to my main speakers and roll off the mains at 100hz ,keeping them analogue, and then using room correction with the subs to flatten the bass . I'm interested to know if I'd have any problems doing that . I'm subscribed. Many thanks