DIY Speakers and Acoustic Panels

We compare different speaker enclosures, the effect of helium on speaker performance and evaluate a wide variety of sound absorbing materials.
REW - Room Equalization Wizard free download: www.roomeqwiza...
Pictures and REW dataset files:
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Find us on Patreon and our website:
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[@theMuBot]

An hour and a half ago I was complaining that I couldn't find data-based comparison of DIY soundproofing/noise isolation methods, made with a good understanding of acoustics, and a friend sent me to this channel. This is fantastic.

[@laurabrown7556]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" That Stops Outside Noise by 80% (25 Db) Tested. Check Here: livesoundproof.com/best-soundproof-curtains/

[@imho2278]

Me too!

[@imho2278]

@@laurabrown7556 doesnt work on low frequencies.

[@arpakyna]

Manufacturers of glass or rockwool usually have absorption efficiency's measured and listed and are far more accurate than any DIY methods. That's really the info you need.

[@rodhart2232]

@@arpakyna no info beats doing it yourself. The reality is, They are trying to get you to buy their product. Far too many sellers/resellers openly advertise false and misleading info in public, take Ebay for example... If one was to click every listing for chinese electronics and report each and every one which was not 100% accurate.... Fark.... it would take a lifetime...

[@cwinla]

In every one of your videos, you answer dozens of questions I've been pondering for years. no hype, no bs, no sales pitch, just the facts! THANK YOU!

[@bruce-le-smith]

100%

[@mrdali67]

It just show that no material is "perfect" for damping, and the ammount of money you put into purdy acoustic treatment panels for your home studio is insane and absolutely not worth the cost unless your a perfectionist and know exactly whats your problem frequencies is or the need of a bass trap at your listening point. The egg shells works pretty well for beeing "free" but so will having just regular carpets and curtains placed around the room, and some bed linnen placed on a hard wood ceiling can remove the worst reflections. Really fun to see all those materials react. It's also pretty inexpensive to just purchase some Rockwool and cut them into manageable blocks and ceil them by sowing some covers for them.

[@parmindersinghnokewal4215]

I leave everything. I put things aside. I give every priority, second priority and start watching your videos as soon as you upload them. These are the best tech videos I have even seen on youtube. Thank you!

[@guffaw1711]

Me too! I do this with videos from Applied Science as well, though I wish Ben's videos would be longer. Even though they are long videos I watch them all the way through in one go, unlike many videos from other science channels which are much shorter. It's because I expect to actually learn something new from Tech Ingredients and Applied Science and not hear the same general information about a topic I already know again and again like on the popular science channels. And I also think engineers make the best educational content for some reason.

[@Jimunu]

@@guffaw1711 check out thought emporium if you like content like tech ingrediens.

[@phredd6070]

At least Im not the only one who does that. I saw a new video was posted and stopped painting the kitchen, threw the brushes and rollers in the tub with some soapy water and clicked the play button.

[@LILLJE]

Sheep

[@electronicengineer]

I couldn't agree any more with your comment! Thank you!

[@TradeWorks_Construction]

I was doing a renovation of a basement that had full concrete walls for the foundation. After framing it out and then adding RockWool insulation I was amazed at the effect it had on my hearing and sound. It was like everything was being muted and silenced the usual background noises present in life … which was extremely discomforting and unpleasant. Not to mention communicating with the others became extremely difficult when we weren’t in near vicinity. As soon as the drywall went up the entire effect was mitigated and all was back to normal. Watching you put your head in the sound chamber reminded me of the experience but i can only imagine how much worse that chamber was.

[@TechIngredients]

According to legend, some workers would have panic attacks when entering an anechoic chamber. I believe it.

[@electronicengineer]

One can learn so much from you in only a single video. I am truly blown away by the sheer breadth of your knowledge Mr. Main Presenter. You are astounding to me. Thank you very much for taking out the time to shoot and edit these videos for us. I really appreciate it and you. Fred

[@TechIngredients]

Thank you and you're welcome!

[@MrRushifyIt]

As an (acoustics) engineer, and a generally curious individual, I seriously appreciate the diversity, depth, and quality of this channels content. While some of the comments pointed out some of the 'flaws' in this video, I think that they are not so important in the big picture. The reason this channel is so great is because they show the experimental thinking behind a creative individual. Thank you tech ingredients!

[@davidtappe5337]

Just read your comment. Thanks for saying how I feel better than I could. Myself saying same thing, “ thanks for the video, headed to Home Depot”.

[@CoincidenceTheorist]

Critical thoughtocasting. Proballama slottening. Connecto dotterdings just as pee wee herman says. Connect the slots. La la la la. Injecło bołs na nah nah na. Infect yo hahtrs c lot lotta clołs. Time fo fooorf shlotss. Insanity dots. Nan no bołs. You are now sending out your own wave bending. Mák ad drèss says yes when scännd they all ünknowns man. 7639 code types. Medïcull pröbés?? Hmm whatta ya kniw. Gotta download a bootoof skanner appp as your phone wont unoesss its older and has nfc specific abilities or so,thing. An old android i once had i bet would do it

[@MichelLinschoten]

I agree as a audio enthusiast, and occasionally speaker repair man for my local community and friends This channel is a gold mine of information, I have acoustical panels (thick compressed wool) in my listening room. And it made a world of difference in overall measurements (almost linear well beyond human hearing range) Never had it sound this good thanks to videos like this . It makes the audio community forum feel like a , absolute joke (in terms of legitimate information)

[@JSAFIXIT]

I agree completely. It's a "nerds" heaven.

[@timekabolden5309]

👏🏾👏🏾👏🏾👏🏾👏🏾👏🏾👏🏾👏🏾

[@theophiled]

Thanks a lot, this will be of great help for improving my recordings! Note to myself : Conclusion for which type of acoustic panels to use --> 47:16 * floor : carpet * ceiling : acoustic ceiling tile * walls : acoustic panels or Rockwool panels covered with a thin layer of cloth (silk or polyester) to prevent the fibers from dispersing into the air

[@thomascaldwell184]

I just want to toss in general support and encouragement-- I love your methodical approach and careful analysis. Keep on doing your thing.

[@RogersAdams]

Discovering this channel has changed pertty much everything. For me the videos are powerful and challenging learning experiences. I liken the channel to meeting a new best friend. By watchig just one and looking at the list of titles I have new ideas and things to discuss with others. This channel makes me even more thankful KZbin exists today. I have often told others had there been a KZbin when I was a child my life would be even better than it has been now for 75 years.

[@DmitryMyadzelets]

The best "DIY Science" video about sound/acoustics I've ever seen on KZbin! Enjoyed every minute of it! Really appreciate all the explanations of what you've done and why. Thank you all. I dived into acoustics year ago having a goal to fix terrible reverberation time (RT60 > 5 sec) in a lecture room. After hours of research over Internet ended up buying absorbing material (panels) to hanger it under the ceiling. But before putting it in place I couldn't miss the chance to check how it would improve acoustic properties of my room at home. So, now I have about 30 measurements done with REW with different number of panels put in different places. Next I'll compare the RT60 curves to see if the results correlate with my intuition and how to actually treat such a small room to get optimal acoustic properties. Here comes the question: Are you going to compare absorbing properties of materials? Having the anechoic chamber you can check how thickness of rock-wool changes its absorbing property, how it compares to others (DIY Perks actually tried reduce reverberation time with towels). The best, to my opinion, would be to evaluate acoustic properties of your, say, living room, and fix it if there are some problems, with all this fantastic scientific approach you have. Thank you again. Some links you and others can find useful: * Safety of mineral fibers (a review): www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/347314-comparative-safety-rockwool-fiberglass-organic-fibers-review.html * Room Acoustic Calculator (many producers, see at the bottom): www.sarooma.de/en/apps/web.html * Master Handbook of Acoustics, Fourth Edition (PDF): www.researchgate.net/publication/243525251_Master_Handbook_of_Acoustics_Fourth_Edition * The Sound Blog of Trevor Cox: acousticengineering.wordpress.com/trevor-cox/

[@nehirpro]

You have worked hard. Watched videos that took thousands of hours yet you are here. Here is your prize... Welcome to the best part of KZbin. Here we people argue over acoustics and it's measurement techs.

[@cho4d]

oh i just noticed, 50 minutes. for most content that's too much. way too much. for tech ingredients content well i guess that'll do... could be longer tho ;)

[@maxlee6676]

so sad..!

[@WhoTnT]

At 2x speed it's only 25 mins

[@procactus9109]

Seems the barrage of adverts filled it out

[@1christian1sonne1]

More? yes please :-)

[@concretesailors]

@@procactus9109 - Firefox has a snap-in to stop the adverts from breaking up the video you're watching. I would recommend this snap-in.

[@SpectrumDIY]

I love this so much (Granted I'm autistic and have Sensory processing disorder, it makes sounds really... quite a lot sometimes, so sound proofing has brought me here), it feels very stimmy to see how effective different materials are.

[@williammorton8555]

Your skill at improvised engineering is outstanding!

[@TechIngredients]

Thank you!

[@rogerfurer2273]

I thank you for all your videos. You cover many subjects I'm interested in. I worked in recording studios for several years and, as far as sound and acoustic design goes, one of the biggest problems in control room design is taming the low frequencies in small rooms, given that a 20Hz wave length is approx 60 feet (1/4 wave of 15'). One of the most interesting design concepts I heard about, instead of bass traps, is using heavy panels suspended from the ceiling and located a certain distance from the wall. The calculations I heard were: the area of the panel determines the effective frequency, and the distance from the wall surface determines the bandwidth. The mass of the panel determines the amount of energy it can absorb. These are used on at least one wall of each room dimension, so one at the back and one on the side. The room I saw these in had one on each side and a third at the back. I would love to see you tackle this subject and test the idea.

[@TechIngredients]

Look up fabry perot interferometers. Interestingly, the smaller the gap, the wider the bandwidth, but the less intense the interferometric interference. I don't know how the area would relate to the frequency assuming the dimensions will always be sub wavelength. I'll take a look.

[@rogerfurer2273]

@@TechIngredients I would think that fractions of 1/4, or 1/8 wavelength would act to absorb specific frequencies. The idea being to tame standing waves in a room that has parallel walls and problems because of that. Of course listening levels will play a large part as the acoustic energy couples more strongly to the structure.

[@bigGWM]

i was just looking to what i could use to build sound panels in my theater in the basement . the room came with acoustic tiles 2x4 feet in the celling like you had good luck with, and carpet on the floor but the walls were wood paneling. the is where my problem is. I have some hot spots with the bass the main one is a corner that muddies up the bass terribly , there are other panels that rattles a bit. i have in past years ive put additional screws that did help some So i took a couple of cushions off the couch and moved the around and found the trouble spots. that s when i decided to build some sound panels. and was trying to fine the best product at the best cost .watching your video was very informative and the way i see it i going to use acoustic tiles. the price is dead on and they will be able to fit anywhere if i have to cut them. Thanks for all the time and cost you put in to come up with a solution that has saved me cost , time and efficiency this really set me on how to handle this. i will let you know how this comes out. Garry M

[@minilab9030]

Listening to a serious engineer who has passion curiosity and extraordinary ability is a thing of beauty. There are so few, but they do such extraordinary work. Thank you for educating other primates.

[@kevineyster1ify]

I wanted to say that I really enjoy your videos. My father was a mechanical engineer and a project manager. He built power plants and refineries, he also was President of Ruston Gas Turbines. I personally did not get my degree however because of the exposure and my ability to understand engineering and physics I watch and study many highly technical fields. Recently I been building high end audiophile grade custom speakers for myself and trying to move into commercial and private elite customers. Your series about materials has helped me make decisions about materials and some of the very small decisions like porting and insulation. I always have thought insulation was a anti speaker additive. In otherwsrds if you need insulation maybe your box is the problem. Anyway love your videos all of them and I would like to see you take on crossover networks and how to build them and test them and the speaker technical specs and what works and what is a waste.of resources.other videos I have watched place your biggest gains in quality of sound can be achieved with a better crossover network.

[@eaglemount98368]

Excellent, informative. I'm building my home system and need and appreciate all the information I can get as a novice. I have looked for a concise video of the physics of just how audio systems function - input signals, preamps, amps, out puts etc and not finding that, am putting together videos and articles that I find informing. This was among the best and most informational. Thanks so much. I'm subscribed and looking forward to more...

[@zoltankaparthy9095]

You are a reminder of a saying from my programming days, "One test is worth a thousand opinions."

[@lisakingscott7729]

On the toilet roll sound absorption, it reminds me of a high quality 1950s loudspeaker which I dismantled many years ago. It used loosely layered tissue, very similar to toilet paper, with a thickness of about 59 to 100mm of the multiple layers as sound absorption material. Most of the thickness was air. The paper was much bigger area than toilet paper and was just tacked into the cabinet in the corner edges of the box. Subjectively it had much better sound absorption than commercial acoustic foam or blanket. The only drawback that I can think of is that it must be a huge fire risk if anything in the speaker or its connections overheated.

[@armandoarellano6405]

This is great, thanks! I was just wondering if the towels were a good material to use but glad I came across this video afterwards.

[@Redsammeh]

Are you a retired physics/engineering Prof? You seem to know a heck of a lot about a lot of topics

[@MrEazyE357]

He won't tell you. Pretty sure he's an alien. Shhh...

[@salvatoremilitello8490]

He has said in several videos he is a retired rocket scientist / engineer

[@unlokia]

"Tech Ingredients" + "Smarter every day" are REALLY REALLY intellectual, educated scientists with incredibly intelligent minds. They put 99% of the go-to, so-called "science" YooToobaz to shame. Experience shows, and most of them don't know jack.

[@AtimatikArmy]

One think is certain, he is 100% engineering minded. I think an unintended byproduct is that engineers make excellent communicators and teachers. Their way of communication is always clear and concise.

[@sturnus111]

I know, but I won't tell.

[@butziporsche8646]

I am using Lowther drivers in horns front and back loaded and valve amplification. I am returning to vinyl as well. This video reminds us of why helium is used to pressurize high performance Sterling engines.

[@rango_dinamico]

Tech Ingredients & Project Farm are the only two youtube channels I need.

[@jesinbeverly]

Tried building one of these once for what was a fairly well know audio company I was working for. The problem was that the chamber, with its large external surface area became a good amplifier for low frequency energy. Turns out, the industrial sized air compressor system was very loud and generally not heard started measuring as very loud. We just limited measurements to above 200Hz.

[@GoodBaleadaMusic]

Shoes are probably the most complex surface you can create. And you can adjust it by filling different shoes with different materials. Like towels.

[@whitlcj1]

22:30 He inserts the helium tube into the port on the bottom of the speaker. Helium rises so it wouldn't fill the box unless maybe he left the regulator turned on during testing. Putting the tube on the top port would allow the box to fill to the bottom port before escaping.

[@victoryfirst2878]

Thank you so much for showing us all on KZbin how to do so many things. Look forward to see more great thing in the future Sir. VF

[@basementphysics6334]

When are you going to resume the rail gun project? I was really looking forward to it.

[@TheSuperVGA]

Merci Tech Ingredients pour vos vidéos ! Regarder cette chaîne est un veritable bonheur !

[@dizzolve]

2:13 so THAT'S where all that toilet paper went

[@argcargv]

It might be interesting to also look at the phase change with different materials. Phase could have a significant impact on the stereo soundstage of a speaker.

[@Testfortest142]

This is the main topic why I watch your videos

[@j.w.5733]

We used Poly Fill( pillow stuffing) in our subwoofer boxes to slow down the air movement and echo effect inside our speaker boxes.

[@sr6550]

Ooh, the long range acoustic projector seems like a nice project to tackle. I really liked this and the other videos you did on speaker designs. Keep up the good work

[@inlandchris1]

Instead of sound absorption, try sound dispersion using mdf and pieces of mdf on top of the mdf board to disperse the sound. It would be an interesting compare to absorption test you already did. Oh, thank you for this test, I really appreciate this.😊

[@ovalwingnut]

Speakers & acoustics aside, so many physics lessons to be had here... Wonderful & COoL all at the same time. BTW, your camera person has it easy today :O)

[@ZoeyR86]

the big drops are destructive interference and is a result of the distance from the microphone and the speaker. did similar testing a few years back i used a 2 way automotive speaker in a tuned enclosure. after witch i took outside with a 50ft of space placed the speaker on a stand 2ft off the ground pointing up and placed my usb mic on a mic stand about 3ft above the speaker and used a dsp and a small linear 35watt amp with a 32 point calibration to to get +/- 0.5db flat line from 80hz to 18k. i use this tuned setup for making room correction filters

[@QuantumDigital2017]

One he11 of a salesman right there. Great YT channel. Keep em coming. QDE 2020

[@StingerPhilip]

Oh Boy...50 minutes I wouldn't love anything else more than to spend watching a Tech Ingredients video.

[@RozsaAmplificationLLC]

Love your videos. Very informative. There are quite a few things to consider when doing experiments such as this. For one, how much wattage was the amp driving the speaker with? It needs to be appropriate for the speaker. Speaker dynamic range changes over power and speakers different. So, so get full range out of them, need to be driven. One speaker may only need 1 watt to drive it to full range, while another may need 5 watts or more! Soo, you should take that into consideration, but considering just side-by-side comparison based on a baseline, can be comparable. just throwing it out there. For audiophile purposes, they like to see 20-20kHz range...but you only used a partial of that and 100Hz to 12kHz. Not sure why, but a standard 20-20kHz would be better. As far as open-back, closed-back, or ported...there are standard calculations for all of this and with porting, you have to take into account a bunch of things such as resonant frequencies, Q-rating, volume, etc. and the porting result will be size of porting and length of tube, not just drilling a hole for porting.....soo wonder how much and calculation went into it to ensure ideal results?? A couple books to reference are: Loudspeaker Design and Construction and Electrostatic Design and Construction which go thru all of this and calculations. Likewise, what type of microphone did you use? There are characteristics for each, but didn't catch it mentioned.

[@Koru-Health]

I really enjoyed this video and thank you for including the helium experiment. The results were very interesting. Keep up the good work!

[@dtebarrett]

I think the towels used in the panels made by DIY Perks were more designed to prevent reverb and reflections rather than to control frequencies. Obviously, these are related, but DIY Perks' main thing is small budget, and for that budget, I expect these panels would reduce reflections in a space.

[@phallus36]

Probably would have been a good idea to put the hard material behind the acoustic tiles during testing as the ones that to have it like the towels will have the sound go through them, bounce back on the wood, through the material and into the chamber, while the sound that is transmitted though the roxul is just going into the room which will most likely affect the results and be less representative of an acoustic panel that is hung on a wall love your videos btw, don't stop making them, especially the ones about acoustics

[@Twongo]

It would be really interesting to see you do a video on why all the measurements exhibit a 30dB dip at about 580Hz when in the big box. Also, what are those symmetrical ripples in the frequency response graphs, such as at 160Hz, 710Hz, 2300Hz in the first measurement. It would be helpful to get a baseline of each of the speakers by placing them face up on as high a stand as you can in the largest open area in which you can do the test outside. Same mic, same distance, same level.

[@ZenDragonJP]

There is a sound quality concern with porting; "transient response" can degrade vs sealed. Did you use TS parameters to design your boxes? Anyway, transient response would be difficult to objectively measure, but experimenting over time with subwoofer enclosures I can say there is an appreciable subjective difference. Also as far as reflections inside the speaker box, maybe as a future video you could construct and test different shape enclosures? Optimally the panel directly behind the loudspeaker would not be flat. The less flat surface area in the box (all sides but directly behind the speaker especially), the more smoother response overall. (Reference: Loud Speaker Cookbook from Vance Dickason)

[@rich1051414]

Porting hurts and helps. It increases the deflection at a given current, but it returns to center much slower. It's what gives ported bass it's 'sloppy' sound. A sealed sub takes more energy to produce the same deflection, but the vaccuum generated behind the cone will help it return to center, speeding up the response of the speaker, making bass sound 'tighter'. Ported bass will sound louder at a given wattage, but it will also almost seem lagged and loose.

[@dustman96]

Though your testing yields some interesting results there are some things to point out. For one thing, the rockwool has significant reflection due to its relatively non porous surface and density, so it's no surprise that it won't change much as far as higher frequency absorption. For that you need a looser insulation material. The results of the test show this clearly, the lower frequencies are able to penetrate your dense insulation therefore are absorbed more than the high frequencies. With a lower density, more porous material you would see very different results, less absorption of low frequencies inside the enclose and radically better absorption at higher frequencies. Also, you stated that there was little advantage to the insulation, but having unattenuated sound waves bouncing around unchecked inside the enclosure is sure to cause distortion. If you don't have insulation the resonances are going to last much longer in the enclosure, causing distortion. Also, tuning enclosure size and port size and length in a ported enclose determines the response you will get, but I guess the test did display the potential to increase low end amplitude. This usually comes at the price of increased distortion. Also worth of note is that in a sealed enclosure the low frequency amplitude drops of gradually, whereas in a ported enclosure you may get increased amplitude over a given frequency range but then it drops of radically under the port tuning frequency. As an aside, I highly recommend the book: Master Handbook of Acoustics.

[@TechIngredients]

I agree. Directing and trapping sound waves within an enclosure will ultimately be more effective than randomly oriented fibers and voids, but our tests do not show that the lack of that absorbtion creates resonance peaks. We didn't try to optimize the porting or the enclosure dimensions for these drivers because as you suggest this is a complex topic deserving much more time.

[@andrewhigdon8346]

Ok so there’s a reason that black foam material for sound absorption is expensive. It’s called R&D, and if mattress foam was nearly as effective, that black stuff would never sell. The individual shapes are pyramids, and the sizes and density of material are crucial. And by using a saw and a lot of time to create your DIY sound absorption panels, you more than offset the expense. Also, depending on how heavy a coat you use, that spray adhesive also has a very real influence on the two materials as far as sound is concerned. Also the reference mic placement matters, but now that the capsule is surrounded by foam, and even the sides are shrouded by the foam, rendering that reference mic a non-reference mic. All if your measurements based on that mic and it’s placement are irrelevant. Sorry, I’m usually pretty positive, but I’m also a sound engineer and this video gives me the shivers. This guy seems way too smart to have built all of this and actually use it for reference testing. So it’s definitely a spoof. That mic placement sealed the deal. They are expressly designed to be freestanding

[@TechIngredients]

The mic is free standing. It can't levitate and is held by a commercial microphone clamp which is in turn supported by a tripod in one case or the wall of the anechoic chamber. Otherwise it contacts nothing else.

[@Beaches_south_of_L.A.]

I don't care who you are, where you are from nor what your background is if you can not agree that this guy is the coolest scientist than I have no use for you.

[@clytle374]

Great video. And I enjoy your engineering mindset, not the like most engineers I work with, but you are a proper engineer. I'll bet you didn't learn most of what you know in school, you started learning before school, you went to school to learn something, probably learned you still didn't know much when you left, then dedicated your life to learning. I spend a large amount of my time thinking/reading about HiFi, and trying to dig through the tanker loads of snake oil on the subject. I did see your video on sound deadening of the speaker cabinets. And have often went down the concrete cabinet line of thought. As noted in other comments here, the effects of deadening the outside of the cabinet were masked by the anabolic Sound Chamber, and the internal reflections will be worse in concrete. So a concrete cabinet would have to be layered up like your speaker build video. I still come to some other conclusions that are not popular: Like a book on current driving loudspeakers I agree with heavily. That low impedance amplifier output doesn't control the speaker well at low frequencies, nor does current drive.. But current drive helps a lot at mid to high frequencies. I also have a issue with most speaker testing as the tests nearly always measures a steady state response of the system. Music has lots of steady state components, but many aren't. Sure a ported box can create a great 100hz tone, but often seem to suck at a snare drum. ESL speakers do them great, and single full range drivers do pretty good. Human ears are actually hardware FFT, lol. Anyway, too much of a topic for a discussion here. Keep up the great videos.

[@mr.boxman2244]

26:45 You say two hundred decibels - but you mean 200Hz, also 3 inches is 76mm, and my experience with cotton towels is that they only work well when layered at least 6 times. Cotton always has water inside and may be unstable with changes in humidity. Other than that I loved the video and will tell my friends to watch it. Thanks for listening to your viewers! I am running my speakers with 410-420ppm carbon dioxide with good results.

[@RogerBarraud]

31:10 Were you just talking during that sweep? :-/

[@davemarm]

Good catch

[@MmeHyraelle]

Yea i hope it was voice over :)

[@adam207321]

We're gonna test that too That gives such a project farm vibe to it :D

[@yoyofargo]

The benefit of a concrete speaker cab might not necessarily be the accuracy in output in front of driver, but rather the decrease in bleed into the surface the cab itself is resting on, as well as different resonant modes of the cab faces. Though simply placing your speakers onto iso pads on top of bricks is probably easier than making a concrete cab.

[@TechIngredients]

You may be right.

[@ayokay123]

Can't thank you enough for all the work you've put into this experiment. SUBSCRIBED!!

[@JS-cx3il]

Would love more details on the build of the foam board speakers and the concrete reinforced speakers. Good luck with the incoming storm!

[@MichaelAddlesee]

Some fascinating experiments. Thanks for taking the time to do them.

[@danielmusat597]

Thank you for all your effort in bringing knowledge to us! Very well designed test environment and test jigs. And lots of explanations, as usual.

[@MasterCommandCEO]

I literally spit out the water I was drinking when you said "This is a beast" LOL

[@caspermaster-com]

When you turned the speaker back, the measurement shows 90% the direct sound of the speaker, at the low frequencies speakers are pushing alot of air back as well, not just forward, you need alot more insulation on the backside of the speaker to do the test intended

[@TechIngredients]

You're probably right.

[@bodobuttner9100]

I love these series.

[@Wizongod]

I noticed that if you put your ear against a roll of corrugated cardboard (along the axis) it actually sounds really quiet indicating that it absorbs sound pretty well. Therefore it led me to think that perhaps stacked corrugated cardboard might be a good sound absorber, but it would be quite a bit of labour to cut them into strips and glue them together to form like a honeycomb structure which can be used to cover walls. Not sure if you've thought about this before?

[@22BOZIDAR]

Back in the olden days movie theaters had heavy pleated curtains hanging on the walls. Haven't been to a theatre in years not sure if they still do.

[@HazeAnderson]

Something else to consider is that the human ear was not designed ...er ... evolved to listen to sound in an anechoic in the first place. We do a great job of processing sounds while moving about, as if our hearing were designed to simultaneously hunt and evade other predators or something I DONT KNOW I am just a drummer. 😅

[@CanalGabrielCoelho]

even in an anechoic chamber, 32, 35 db looks like very low power delivery even for a very inefficient one. Enclosure wall rigidity is much more important at high power situations, closer to the mechanical limits of the speaker and much higher pressure changes inside the box. Starting the test at 100Hz also reduces much of the advantages of a rigid box, once low frequency moves much more air and will cause much more wall distortion that will affect sound. A low frequency high power setup would be much more sensitive to the advantages of a concrete super rigid box instead of a lighter one.

[@haroldemmers3678]

Very nicely done. Would be cool if you could try something like what they used in old churches. I believe it was called Helmholtz resonator cavities.

[@outspokeninsider752]

Sound absorbtion and diffusion are different. Just changing the waveform enough to be distinct to the ear from the original produces a larger psychological effect than is measured, making egg-cartons 'not useless' for difraction, but very poor at absorption. Thanks for the great videos!

[@epictimebreaker]

this is some unique content on youtube! good job keep up the good work!

[@TechIngredients]

Thanks!

[@matthewmoore2839]

When testing the materials for reflection it would have been interesting to see a comparison between the performance of the same driver/enclosure in the anechoic chamber to the measured performance of the material, to cancel out the characteristics of the driver and enclosure itself.

[@walthodgson5780]

You should put some padding on your knee board, and maybe casters on the edge to make it easier to move.

[@Kaxlon]

A essential must-watch video! Thank you so much for sharing your results. =) And yes, I sinned by downloading the video.

[@maxa2826]

You should do a harmonic distortion test on the different enclosure types. While frequency differences may be small, distortion differences could be large. Lower enclosure mass+stiffness leads to phase-delayed re-radiation of the rear wave into the room, which would show up as harmonic distortion.

[@psycholocke4090]

Thank you so much for all the efforts put into your work. I would have suggested that when using the towels, that you put more layers more compact. More like DIY Perks did. To give them at least a chance in regards how foam is build and works. During my work I also stumbled across densely packed rock wool sound absorbers. So nice to see their raw performance. I would be curious if you can get you fingers on something like "Basotec" a wood based material I heard of. Great Work!

[@Sunnyskyguy]

YOur chamber although nicely absorbent in initial tests had a 1/4 wave null at 600 Hz and 1/2 peak at 1200 Hz which produced the sharp null and smooth peak respectively. You do not need significant SNR to make these measurements and would get a flatter response outside even at low levels. I've noticed similar differences in Faraday Cages vs outdoor FCC tests, except the room had a resonance at 60 MHz. That explains why your room measurements avoided those. All the notches are equivalent to Rican Fading loss. (multipath 1/4 wave cancellation)

[@SCM]

Something you should test with the concrete enclosure: Transient Response. Frequency Response is just one thing in a good speaker.

[@beerstein7137]

Suggestion: I know this video is already a few months old, but if you still have the setup it would be interesting to compare the total harmonic distortion of the unpadded and padded speaker boxes. I have a hunch that the padded boxes may reduce the resonances of the higher frequencies inside the box, and therefore to harmonic distortion.

[@tjns3]

I would love to see you take on making a diy isolation cabinet for guitar recording. Many are able to get decent sound reduction, but the recording quality due to the standing waves is the challenge. They all sound boxy. Combining your panels, active cancellation, microphone selection and dimensions could be pretty interesting.

[@Khunvyel]

I just love your videos :) thus here are some pointers and thoughts: 19:11 You would have done yourself a better service if you left the speaker in position, and THEN just unplugged the ports to further reduce the margin of error by a slightly different placement as you put it back later on. Same with with more preparation for the helium insert. You don't have to film things chronologically if it messes up your tests. You could've showed us the details after you ran the test and put it to a better display for the camera to see about the helium plugs :) 23:48 I would be very careful with stale analytic measurements and comparisons like that. Just from a mechanical point of view, each time the speaker moves back, it is because at this given time the soundwave drops below the zero amplitude point. If you give the speaker a different resistence in one direction than the other, this is likely going to falsify the end product. Averaged Frequency analysis is not going to show that to you. You have to listen to what comes out. 27:10 It basically comes down to mass to most of us. The more mass, the better the bass insulation. Other than that it requires a lot of nifty constructions :D Apart from certain material science. 40:17 The difference might be small enough, but the egg cartons as well as the towels have one big issue: they are a fire hazard. The towels can be at least enclosed in some form of fire retardant and take less volume at that than the egg cartons. I wouldn't spray the egg cartons with anything. You can get polyester towels which aren't going to be affected by microbiologics. Egg cartons are essentially paper, thus wood fibres, so you're going to have a whole different problem with soaking up humidity and providing breeding grounds for mould and fungi. Never use egg cartons. Ever. 42:19 Have you done a weight comparison? It looks like the toilet paper rolls will score among the highest weight of the panels you showed, and they also have the greatest depth on some portions of that lattice whenever the outside layer is struck by sound. From the outermost toilet paper layer to the innermost one, this has by far the most depth of all the other materials. So again, we're at the well understood principles of mass and material depth, hence why any good listening environment is hung from the ceiling with substantial space between all solid walls to but dampening material in :) 47:46 if you use the rock sheets, apply some form of pore-closing spray on it. Anything will do, really, from wood primer to automotive primer, just to keep the outhermost layer closed and thus stopping it from giving off particles. Then slap on the cloth. The magic trick is to dampen the sound equally and only curb the frequencies more which are standing out in your room because of natural acoustic reflection of that particular shape. What really helps the most is random refraction which is best done with randomized half-spherical objects. So differently sized hemispheres (and even slightly differently shaped, like ellipsoid and some with slight angles) of one material mounted on another material and likely at least one other material behind that layer too. Ideally, those hemispheres are mounted on a thin standoff and the rear of the hemisphere is corrugated as well as the opposite mounting side. What I personally really would like to try is a physical representation of dithering and the dither material is irregularly refracting. However, I don't have the funds, nor the space, nor a volunteer to help me out :D Because it would be quite the spacious and I don't have that here on my own. It's going to be quite space-consuming.

[@Not_Sure_]

@2:06 LOL 🤣😆 Love it. And that is a classic.

[@nlingrel]

I hereby nominate this guy for Coolest Dude on the Internet.

[@ryanturpin5114]

You should look into acoustic suspension speaker designs. They fell out of favor because they weren't as efficient but my AR 3a's reproduce low frequencies better than about anything else I have ever heard. Not sure where you would be able to find suitable drivers but it is a design that I wish would make a comeback.

[@SuchtFaktorHoch10]

@3:35 As soon as he said "...to infuse Helium behind the speaker..." I had a nerdgasm.

[@billyjukes9990]

The toilet paper and foam fronted rockwall are actually performing better in the lower frequencies due to their effective thickness. The RT60 measurement will show this. Compare your anechoic measurement to these measurements. The closer to the anechoic measurement the better for clarity. The other materials/the room are actually reinforcing the lower frequencies which isn't necessarily a good thing

[@denarjan]

They performed better because the tp test was missing a hard reflective surface behind them, like all other tested panels had.

[@borat6363]

Excellent video, well worth the wait!

[@jeffreyjbyron]

Wish you had done Ownes Corning also, since that's what so many use to build panels.

[@Andy-pu2iv]

Oh such fun. Takes me back to my university days!

[@mavos1211]

Would there be an improvement if you made a “sandwich” with acoustic ceiling tiles either side of the Rockwool type panel? Once again outstanding quality video, my only complaint is that it was over far too soon! I have waited for the perfect moment where I could sit down and watch with no interruptions whatsoever. Well worth the wait!

[@TechIngredients]

Probably. That is why we ended up using double layers of Soundboard in the anechoic chamber. Layering helps. And thanks!

[@rocifier]

That chamber would be so much faster to rotate open and closed by using a latch clamp on one side, and large hinges fixed on the other side. And then mount a basic laptop on the side so you don't need to keep walking across the room :)

[@DullPoints]

Best content on the internet!

[@chefntoast]

Human malware event ... I love it!!! Keep doing yalls thing . Yall are great!

[@jvkew]

Many years ago I made a set of speakers called ;sweet sixteen'. Each was a 4x4 grid of 4" cheap speakers. They were a marked improvement over the speakers that came with the stereo. Have you heard of this?

[@alachance2010]

I'm so happy there's finally another upload! Woooo

[@steveking4966]

This is one of my old bugbears on all speaker design, the idea i had for a design was too form cob (mix of chopped straw clay and manure), my idea was too build them into a room 6.5 x 7-7.5 trapezium 2.7m high. Why you ask becuse the cob should completely negate resonance, therefore isolated speakers or inbuilt , just thinking! like this experiment, thankx

[@dustman96]

I'd be very interested in seeing an experiment using rounded surfaces to diffuse sound within an enclosure or a room, compared to using absorptive material.

[@AM-dc7pv]

Awesome video, surprising results. For the LRAD, are you doing a general area denial type or more like a SASER type setup? Looking forward for the next video. Pretty excited, thanks!

[@TechIngredients]

It's relatively simple. Multiple, very powerful horns driven with 12V automotive amps for portability. I'll discuss the more sophisticated issues, including safety/risk, but the system is pretty simple.

[@marlonprice4165]

Great video! Thank you for sharing your knowledge. I'm going to build one of these chambers to play around with one day

[@lazamarius1]

Maybe someone else already said this but if you would have used the "narrow" side of the box to hang the "shelf" then you wouldn't have needed the knee board thing at all since you could reach the shelf from standing position.

[@TechIngredients]

Thought about it, but because the "door" moves, a complex set up will swing and there is some risk with that.

[@Cyber_Nomad]

Also can try making wooden frames and stretching towels over them like a painting

[@TechIngredients]

Yes.

[@ThisRandomUsername]

Very interesting. As this is a very useful video to reference back to, you could put timestamps in the descriptions or a pinned comment à la a Gamers Nexus video. That splits the time slider up into labelled sections one can quickly locate. Edit: I also thought the egg cartons were meant to deflect sound, but I guess that doesn't happen at any reasonable frequencies because the wavelengths are too long.

[@TechIngredients]

Actually they might if they were randomized like a base trap. Despite it's sub wavelength dimensions it can create diffractive interference.