The short answer is bass traps work to reduce sound energy in a room in the bass region. There are basically two types: velocity and pressure. Velocity is that rockwool or fiberglass or foam and it slows the speed of the sound as it passes through it. Think of waving your hand through water as opposed to waving it through air. It takes more effort and therefore uses up some of the energy the wave has. A pressure trap works by reacting to a low frequency wave in the same way you can feel the floor or walls vibrating when a subwoofer is pumping out dance music. That vibration also uses some of the energy from the sound wave, reducing it. Biggest problem with pressure traps is they are limited to a very narrow band, while velocity traps are more broad-band, covering more frequencies. In an upcoming video I'll measure the frequency the wall panels I made vibrate and get a better idea if they are actually doing anything.
How about destructive interference. Could you build a "bass-cancelling" system? Hard to only cancel the bass waves that have been in existance for some amount of time though. Hmmm. Great channels (woodworking too!)
I used a combination of both pressure and velocity methods on my dust collector. Worked great, as the pressure was targeted at the main tone, while the absorbers cleaned up the rest. 21 dB reduction!
@@ericsimonson3128 Very astute question. Yes, destructive interference or cancelation designs work very effectively. There's different types; Years ago Nelson Pass designed the Phantom Acoustics Shadow... a mic/amp/woofer system whereby in a 7' tall column, with woofers at each end, would "eat up" and null the excessive bass energy... via an inverted polarity approach. If I remember correctly, I believe Stereophile covered in a review. Easier and something any enthusiast can assemble is a DBA, Double Bass Array, somewhat of a pitch and catch system. Ideally it's comprised of four subs on the front wall, four subs on the rear wall. Again ideally the drivers are spread out... one driver in each corner of the front wall (bottom left, bottom right, top left, top right) and a mirror image on the rear wall. Via adjusting the delay/polarity of the rear wall sub drivers, acoustically you can theoretically null all resonant behavior occurring front to back. Pitch and catch. This can dramatically increase clarity and resolution within the bass range.
As an electrical engineer I find this very interesting and refreshingly free of nonsense and voodoo. Since I haven't really studied acoustics, most of this is new to me (but it fits in well with what I know about wave propagation).
I really dig your content. The mis-understanding of what you're doing and explaining is staggering... and you explained it quite well. Two important characteristics of sound in small room acoustics... that many people are entirely oblivious to is wavelength size, and why that matters, and secondly... behavior in the time domain. Perusing these comments so many that took the time to comment ... just haven't got to the point in their audio journey of being exposed to and understanding the time domain and what you're pursuing here. The muddying effects of latent energy in the bass octaves is one of the biggest issues in HiFi. A room subjectively sounds better when it's reverberation is relatively uniform top to bottom. Most all rooms possess excessive reverberant energy in the bass octaves compared to mids/highs. With the mids/highs, if it's not direct/early reflections, then ideally you want to retain that. So, it's prudent to attack that excessive energy without overly affecting the mids/highs ... otherwise you're not evening out the ratio. Damp the bass as effectively as possible, while working to retain adequate liveliness in the mids/highs. Merely wanted to drop a note in appreciation of your content. Didn't intend to add all this, I know you've got this. All the best
Great work... super valuable that you went thru and measured at each juncture... you know audio folks love to disagree or pontificate about method (I’m not saying it isn’t important) but the results are what matters... and you have certainly improved the response of the room!
This is by far the best build video. The waterfall graph is the only thing that matters with these treatments and acoustic panel manufactures never include it in their testimonies. John has a completely square room and made it work with proof. Outstanding!
I have to say your efforts paid off quite well. People may not understand by simply looking at the graphs, but the changes are fairly dramatic for what you can expect.
After watching maybe 100 videos, this is the one that best seems to capture every aspect of acoustic treatment and "sound proofing" in a coherent and easy to understand way. I love the professionalism of Acousitc Fields, but between the sales pitches and abrupt end of each video, I had to watch dozens to get this much information. Great job, and to anyone else poking around, this is a great place to start and get a solid understanding of how sound works in a space.
Very nice step by step and great results. There are times when I want to rip everything out and just start all over again but there are just too many other projects on the go at the moment.
Your room is sounding pretty good John, good work. Like what I'm working with right now is targeting specific frequencies, more to learn about that for sure. It gets problematic for sure the deeper down the absorbent rabbit hole you go :)
Hey John, Great video! I find your woodworking videos fantastic because I used to be a carpenter and now I'm a sound designer working in film and TV. I used my construction 'skills' (Not so great anymore haha) to build studios and currently on my 5th and last one. I am no physicist but I am in love with acoustics and I do know the fundamentals fairly well, though, like you said it's an extremely complex topic. You mentioned that your room is too small for the waves to bounce around but that isn't true. A 80Hz wave is roughly 14 feet, which explains your RTA readings as well as the harmonics. You can also prove this in your shower, just make a high end to low end sweep with your voice and you'll hear the tub mode pop as you get really low (Mostly a harmonic of a higher frequency but its a fun test). The trick to stopping modes or standing waves is to cut the frequency off 1/4 into the wave, so a trap that's 3.25ish feet would stop that pesky 80Hz mode, practical? NOPE so to get around this is you find material that soak up the frequencies that are being an issue, Rockwool is great because it is relatively good at soaking up lower end frequencies, at least in its coefficient tests. Though the thicker you make a rockwool panel the more low end it will reduce (but like you said take away the high end). The resonant absorbers that you've made are a great way to save space. The issue with modes is that only the lower end ones are a problem because they are the ones that fit in smaller rooms and they are the most noticeable, there are so many higher frequency modes in your room but they all are un noticeable as they are too numerous. So the theory that I build into my studios is, use as much rockwool as possible to soak up the low end, then treat the high end with quadradic diffusers. A reason I don't like resonant absorbers is that they are tuned to a specific frequency and any change in the room, like a couch will change what happens and the math gets out of hand. I'm a really big fan and I hope you take this information well! Great video again John!
I didn't say they won't bounce, I said they don't fit - a 20Hz wave is 56' long. 56' is bigger than 14'. Not sure why so many people choose to misinterpret what I say. The room modes are 37hz, 40hz and 70hz - length (slightly more than 14.5'), width (14') and height (8'). You calculate that by doubling the dimension and dividing that into 1130. The first harmonics are 74, 80 and 140.
@@IBuildIt hey John, well what you said is that the frequencies involved don’t fit in the room but they do. Anything over 80Hz fit in that room and would cause problems.
My first thought when I saw the video title was " Why is John making a video about fishing?" . Then I noticed it mentioned acoustics. Interesting topic, thanks for the video. :)
Spacing of the panel off the wall is basically allowing you to get almost the same absorption as if the entire area depth was treated. There is a big misunderstanding going on where many people are claiming that an air gap is better than full depth absorption, when in fact it is the opposite. However, using an air gap can reduce the cost considerably (if you build several panels) while attaining almost the same performance.
Live sound engineer. Current times mean outdoor venues with power issues meaning portable generators on a budget. Noisy!! Been struggling with building sound enclosures. Reading as much literature as possible and watching TH-cam videos. Glad that I was a drywall metal stud carpenter in my younger days. In some of the literature, I've seen where 25 gauge metal studs are better than wood for sound reduction even with the sound transfer of metal. After hearing you talk about the plywood giving a little (in and out like a speaker cone), maybe that's where a high gauge metal stud would be better than a wood stud, in that it has more give. Just a thought. Carl P.S. I like how you are working through a problem with no perfect solution. I feel your pain!! LOL
Disclaimer, I too am not an expert, but as a music teacher and musician I have done a fair bit of study in the acoustics field. You make great points here, bravo. You mentioned the problems associated with a square room, but almost equally important is the reflection of sound waves from parallel walls. If it is not too late in the progression of your construction, I would build out at least one wall at a slight angle from its opposite wall.
Apparently (from my own research on this) the walls need to be angled by a large amount to have a significant impact. Angling the walls also wastes space, unless they were part of the original room layout - moving an existing wall to angle it is well beyond the scope of what I'm doing in this room.
This isn't necessary if the room is acoustically treated. You will still have standing waves with any room shape. All you do is shift the room moods around.
you have probably build better acoustic treatment in your room than you’ll find in majority of professional recording studios around the world . well done!
Good luck with getting rid of standing notes with in a 8 foot tall sailing But you do give some really good tips an you do have a really good understanding of how acoustic works
I am not sure if you are using the same equipment you do for the shop videos but the sound from this is very clean, easy to tell that the room is well treated. Hope everything lives up to expectations.
Kind of and I can see where you get that from my train comparison. The treatment is used to pull some of the energy out of the low frequencies, like putting a pillow over someone's face that's screaming at you :)
I have 4 bass traps and several panels that I built for my main listening room. I have the bas traps from floor to ceiling in the corners, triangle-shaped and free standing one on top of another. You seem to have gotten good results however. I wanted something quick and easy so I just dampened the hell out of my room :) Edit: some panels are on the sides and I hung two from the ceiling over my listening position.
Theater is looking good. I don't know anything about bass traps, but have used dynamat for car stereo installations in the past, of course the purpose is different. My Denon AV receiver has a multipoint EQ that is set up with a microphone, would adding bass dampening via panels improve the curve then, or what if the room already has drywall. Interesting stuff.
You're on the right track. But if you want a "warm" room sound but block out bass travel to the exterior I've got one word for you - Acoustiblok. Hang it like drapes around all of your outer walls - then put up the baffles and panel you have leaving about an inch airspace. Concrete. The floor is going to be a resonance problem. This is what I did - I have a metal building behind my house. Half is storage, half is my practice room. The walls are coated with spray rubber undercoating (the whole building) - seals, helps keep vibration down, minimal soundproofing. Jam room is built room in a room. Outer walls and divider wall are insulated with rockwool then 2 hanging layers of Acoustiblok from ceiling (8ft) to floor inside a 2 inch airspace. The inside wall is another layer of rockwool. Foam tape on all studs including frame to floor. 5/8 plywood walls, floor and ceiling. Floor has a layer of Acoustiblok between the concrete and a layer of plywood. I did this after the fact when I found out that carpet alone wasn't gonna do the job. Doubled door entry with both doors layered. Building has 12ft side walls and 14ft peak. Ceiling (or attic floor) has Acoustiblok, rockwool, Acoustiblok between ceiling studs then plywood on top. Used as extra storage space in building. Interior is cover with sound absorbing foam with foam corner bass traps. I'm a bass player so If I don't rumble no one else will that comes to jam. I wanted as "dead" a room as possible so it doesn't bother neighbors. The most vulnerable part is the entry. Testing at the door is 47db with a full band inside at a db level of 147! 20 ft away - nothing. My house 40ft away. Nearest neighbor to building 90ft. Mission accomplished! Nice room you've got going John. But if you're looking to keep bass travel down you'll definitely need to cover that concrete and ceiling and some corner traps which a panel across the corner about 12" wide with holes half the size you have on the others and then an 18" wide panel with the same size may create a catch in the corners for you. Currently helping my brother build a studio and that's an idea out of many we've had to keep the main room "warm" and "live' for recording. Anyone interested in keeping sound travel down should definitely check out Acoustiblok. Good product and very helpful people there. PS Putting Acoustiblok and a layer of plywood under the carpet made a 26db difference.
For some reason, I'm envisioning you recreating the old Maxell "Blown Away" commercial, the one with the guy in the chair getting "blown away" by the amazing hi fidelity of the cassette tape (amazing that was in 1979, damn I'm old).
Cassettes were great, I think I still have a few of the ones I had back in high school (early 80's) here somewhere. Nowadays everything is on my computer - everything else is too much work and that's especially true for vinyl.
If you don't want to drill all those holes, I hear you can also put up panels with slits between them. Like slim vertical boards with space between them.
Great video! One suggestion: use hemp wool instead of glass fiber! Same effect but doesn't kill you slowly when breathing it in! You can use wood fiber as a substitute for rock wool, but rock wool isn't as deadly as glass fiber (still not great to breath the stuff) and its harder to come by in the US.
Could you try a Helmholtz resonator at 40hz to try to fight those modes? I have seen some built that sit in the corner and look like a small trash can.
The one thing that this video gets across well is just how large you really need to go to get significant taming of modes as low as 40hz. Most videos have no measurments and make exagerated claims as to how big a difference a couple of panels will make to the bass response
your frequency graphs look like it made a pretty big difference in the low end. thanks my room def needs help. im going to use your holy bass diffuser trick. 🍻
Something you don't mention, and most people don't understand, is that most sound you hear indoors is from reflections. You hear the initial sound from the speakers, and then 100x as much sound being reflected off of surfaces as it bounces at 700-ish mph back and forth, reducing in strength every bounce. Your efforts are redirecting or reducing the energy of those reflections, and therefore the amount of times they continue to come back to your ears at a significant level. What's left over is easier to listen to, and more accurate to the original recording in the case of music.
I am curious about how well your plywood wall membrane will work for low frequency capture and /or diffusion. Whisper wall uses a similar approach, but the material they use is much lighter than wood. To capture anything below 800Hz, I would suggest leaving gaps in the wall panels along the rear wall, that are covered with acoustically transparent cloth. If possible I would have these openings run from floor to ceiling and be at least 2' wide. This should work as a bass trap down to about 80Hz, and diffuse a portion of the the frequencies below that. *Edit- My apologies, It would have helped if I had finished the video before writing my comment. You pretty much did what I was suggesting, but you placed two on the front wall and have a semi-reflective surface on the front of the trap. I like how you approached it though.
I am personally designing / building my "Dream" wood workshop. I have been down the rabbit hole of sound in an effort to to reduce the sound that is inherent to a shop and also for music. I can listen to this video and without question "hear" that the room is "treated" ( it sounds good, and I am sure will only get better ) and looking back at your shop videos its now amusing to watch one of your videos from say 2015 vs your more recent ones. Could you maybe do a video showing / explaining the treatments you have in place in the shop? GREAT VIDEO!!
First thing is you need speakers that produce the sound, you need an equalizer, and a true microphone to measure the sound waves, I would suggest that instead of trying to make the room conform to your speakers, I would make the speakers conform to the room by proper equalization, lot less work and better results. I would suggest instead of spending money on wood I would spend the money on a Klipsh horn speaker, or if you like room shaking bass a set Electro voice 18 to 30 inch bass speakers. Then use stuff like mirrors and carpeting in your room with the true mike and equalizer to set up the room, you will also need a decibel meter to set up the separate frequencies. Used to do this years ago when I was younger, set up one disco with Electro Voice speakers and told him do not go past 1 watt, you may deafen people, on opening night he went past one watt and shook the color show glass box light out of the floor. Gave me a call the next day and said you where not kidding, I told him that was my job. And yes people no matter what they say today about sound, what we know today will be obsolete tomorrow. Me I will stay with the mighty Klipsh Horns for real sound, and Electro Voice for speakers that will bring down the walls of your house. There was another speaker I believe they where B&W that gave amazing sound but you needed 1200 watts of power to power up that speaker.
Great story... love hear things like that! However you're discussing the 𝙛𝙧𝙚𝙦𝙪𝙚𝙣𝙘𝙮 domain,... here John is addressing the energy in the 𝙩𝙞𝙢𝙚 domain. He's damping the bass ringing in the room.
Try lead flashing sandwiched between sheets of OSB and drywall. Lead is ideal because it's thin, heavy and soft at the same time, so it absorbs maximum energy. It's the secret ingredient in a lot of recording studios.
@@manamimnm My windowless wall is in fact a garage door (brick and concrete town house). The other side is a busy city street. I insulated the inside of the door as described: osb-lead-osb-dw. I sealed the edges of every layer to the floor, ceiling and walls, and sealed any seams, to prevent air leaks. Leaks = noise. I can't hear the outside noise at all anymore, and mics aren't picking up anything either. The only exception is construction works causing vibrations coming through the floor.
You should try to move your sitting position a bit forward or backwards from the center. The center of a rectangle room is bad to start with and probably worse in a square room. I tend to move backwards from center in smaller rooms because speakers need room to breath, but I'm sure you know that you can't get too close to the back wall, or it will open up a bunch more problems.
Hey John, you might want to put a sheet of thin plastic film over the fiberglass before putting the cloth and slats on. Failure to do this with overhead treatment will allow the very fine glass particles to rain down (I'm not talking downpour here) and you will see this depositing on your furniture - consider too that you will also be breathing this in while using the room.
It's ridiculous to think that enough small particles will get through a tightly woven cloth to be any significant problem. Tell me, are you a proponent of wearing a cloth mask to stop a virus and get unnaturally terrified when you see someone who isn't wearing one coming toward you? If so, can you see the contradiction?
@@IBuildIt OK breathing may not be so much of a concern. I am referencing discussions I had on John Sayers Forum sometime ago and we were more concerned with this dust building up over time in the faders of a mixing console and other equipment. I realize you're not building a music studio, so maybe it's not much of a concern. I just thought I'd mention it for consideration. As for confrontations with mask less people - no I don't panic, happens almost daily here in rural Switzerland - though I would get upset if they coughed on me.
@@sunpointstudio4472 Ah - a forum - the birthplace of the art of making mountains out of molehills. On a possible list of considerations when doing something like this, the one that concerns the amount of dust that's able to make it through the fabric should be on the last page at the bottom. It is a completely insignificant factor and anyone who's done this knows that.
Rooms need to get up in 30' x 20' with 12' ceiling range before they start to stop being challenging for bass. And you don't find rooms like that in the typical house these days, unless your house also used to be a church :D
Small room acoustics is a secondary professional interest for me. Most of your room treatments are good, but I was surprised to see the TV on the wall at the end. You need the Diffusers on the rear wall not front for best imaging. Read up on mirror points, Haas effect, etc. if you had more Diffusers where the TV is, that would be a good design for the rear wall. From what I can see on the brief plots, you did a good job on reducing bass modes. A waterfall plot shows this better than the spectrogram in my opinion. I have never built a QRD, for work I just buy them. You might consider improving your design with a scaled version in each cell to extend the range higher. I have seen plans for doing that with strips of MDF.
I need the TV and from what I've learned about this having it there behind and between the speakers is the single best place in the room for it. The rear wall will have more diffusers with more bass traps, but it also has a doorway that needs to be dealt with. After the build in stuff is all done, I'll make some free standing absorbers for early reflections and additional treatment.
What’s the thickness of the plywood you used for the diaphragmatic absorber, and what would you suppose would be the affect of using a thicker plywood? Thinner?
Thanks for the video. I cringe when I see folks use the cheap studio foam and claim "we are now sound proofed, neighbors can no longer hear us" :( I'd love to know how you are treating isolation though, your thoughts on tube/tuned traps, and if you've tried making waterfall graph (which are my go to personally). Also, have you considered shortening one wall to avoid the perfect square, or angling it slightly.
Isolation isn't an issue for me. It's quiet where I live and my neighbours are far enough away that any noise I make won't bother them. As for tuned traps, they need to be huge to work at really low frequencies and also need to be in the right place to work well. Angling the walls does very little, from what I understand. They'd need to be really angled to make an improvement. The charts I posted are spectrograms and they are just like looking at a waterfall plot from above.
What if I built a free standing panels, in a roundish cubicle around my desk. No corners. Leave gaps so pressure can escape. A cloud above my desk. With gap. So pressure again can escape. So my room can remain a live room, it’s all wood. But when I mix, I pull the absorbing panels around me, in a circle ⭕️
Very interesting. What. program and test mic and sound source are you using? I use a homemade dodecahedron speaker and an Earthworks M30 mic. Just FYI your room is too small to develop a true statistical reverberant field. You are dealing with cumulative spectral decay. And yes you have a massive amount of modes in the small room plus flutter echoes. Some of you assertions are not 100% correct but close enough. You might consider a Helmholtz resonator trap in each corner at the fundamental freq of the lowest room modes. You also need add diffusion to the rear wall. You should get tbe book Master Handbook of Acoustics by Alton F. Everest. Keep it up and i enjoyed the vid
I never said I expected a diffuse sound field in a room this size. What I did say was the goal is to get the reverb time as even as possible. "Aiming for" and "expecting to hit" are two different things. And since I'm not an expert or even pretending to be one, like I said in the video, it's to be expected that my assertions wouldn't be 100% correct. I'm using a Umik-1 and REW to do the measurements. Speakers are Elac's.
Does the TV panel add any bad reflective noise? And would a projector screen be acoustically transparent like cloth? Very interesting video I love the new channel addition to your lineup.
Being behind and between the speakers is about the best place for it, since it's not getting a lot of direct sound. Probably won't be a problem big enough to solve.
You've mentioned the walls - sides, front and back - and ceiling; but, been quiet about the floor - so is that tile for echo or carpet or futons and pillows tossed about for additional careful sound throttling? Presumably, to be addressed in another episode (I'll be patient).
I'll eventually do wood on the floor, but in the meantime have thin carpet tiles. Floor is generally not treated, especially when you can do the full ceiling.
@@IBuildIt I've attempted a little additional research into acoustic floor treatment this morning too and what I've come up with so far is that that is usually left to dust balls and pet shed hair accumulating naturally - but that's just from sweeping, I vacuum later today.
I love music, play guitar and piano, but would never claim to be a true audiophile; probably because I've destroyed my hearing trying to imitate Alex Lifeson :) I only mention this to say that even if I couldn't tell the difference in the sound at all, it looks cool as hell!
I totally transformed my square room’s horrible low-freq sound by doing it via the CHINA method….cheaper, simpler, most effective method i hv encountered. No need to buy lots of fiberglass, rockwool and no need to fill the room with such a huge qty of panellings. In my country, we call it “plaster ceiling” which is the American drywall done on the ceiling with a huge airspace behind it. In short, simply create a slanting, fake ceiling (from drywall material) so that your entire ceiling is sloping in any direction. It will totally transform and normalize the horrible low-freq behaviour of any smallish squarish room. If you dont wanna slope the ceiling, then you can slope/cant/slant ONE wall…any wall. The results are amazing and the room’s size doesnt diminish much while looking so clean. The above were done to 2 highly problematic videoconferencing rooms during the Covid lockdown as taught by a China-based German acoustics specialist, and he simply calls it the China method….clever, efficient, cost-effective…thinking out of the box👍
The short answer is bass traps work to reduce sound energy in a room in the bass region. There are basically two types: velocity and pressure.
Velocity is that rockwool or fiberglass or foam and it slows the speed of the sound as it passes through it. Think of waving your hand through water as opposed to waving it through air. It takes more effort and therefore uses up some of the energy the wave has.
A pressure trap works by reacting to a low frequency wave in the same way you can feel the floor or walls vibrating when a subwoofer is pumping out dance music. That vibration also uses some of the energy from the sound wave, reducing it.
Biggest problem with pressure traps is they are limited to a very narrow band, while velocity traps are more broad-band, covering more frequencies.
In an upcoming video I'll measure the frequency the wall panels I made vibrate and get a better idea if they are actually doing anything.
I am building a recording/live streaming studio in my basement...and this is some awesome info. Thank you, Mr Heisz.
Those 'holy' panels remind me of a QR code.....
WOW! Just scanned one and it directed me to woodgears.ca!!!
How about destructive interference. Could you build a "bass-cancelling" system? Hard to only cancel the bass waves that have been in existance for some amount of time though. Hmmm. Great channels (woodworking too!)
I used a combination of both pressure and velocity methods on my dust collector. Worked great, as the pressure was targeted at the main tone, while the absorbers cleaned up the rest. 21 dB reduction!
@@ericsimonson3128
Very astute question.
Yes, destructive interference or cancelation designs work very effectively.
There's different types;
Years ago Nelson Pass designed the Phantom Acoustics Shadow...
a mic/amp/woofer system whereby in a 7' tall column, with woofers at each end, would "eat up" and null the excessive bass energy... via an inverted polarity approach.
If I remember correctly, I believe Stereophile covered in a review.
Easier and something any enthusiast can assemble is a DBA, Double Bass Array, somewhat of a pitch and catch system.
Ideally it's comprised of four subs on the front wall, four subs on the rear wall. Again ideally the drivers are spread out... one driver in each corner of the front wall (bottom left, bottom right, top left, top right) and a mirror image on the rear wall.
Via adjusting the delay/polarity of the rear wall sub drivers, acoustically you can theoretically null all resonant behavior occurring front to back.
Pitch and catch.
This can dramatically increase clarity and resolution within the bass range.
As an electrical engineer I find this very interesting and refreshingly free of nonsense and voodoo. Since I haven't really studied acoustics, most of this is new to me (but it fits in well with what I know about wave propagation).
The lack of nonsense and voodoo (and believing in measurements and not just my golden ears) means I wouldn't make it in the high end audio business :)
Actually, scratch some of that - there are a few that don't that I highly respect.
@@IBuildIt
Check out *Erin's Audio Corner* on TH-cam and his website if you haven't already.
I really dig your content.
The mis-understanding of what you're doing and explaining is staggering... and you explained it quite well.
Two important characteristics of sound in small room acoustics... that many people are entirely oblivious to is wavelength size, and why that matters, and secondly... behavior in the time domain.
Perusing these comments so many that took the time to comment ... just haven't got to the point in their audio journey of being exposed to and understanding the time domain and what you're pursuing here.
The muddying effects of latent energy in the bass octaves is one of the biggest issues in HiFi.
A room subjectively sounds better when it's reverberation is relatively uniform top to bottom.
Most all rooms possess excessive reverberant energy in the bass octaves compared to mids/highs.
With the mids/highs, if it's not direct/early reflections, then ideally you want to retain that.
So, it's prudent to attack that excessive energy without overly affecting the mids/highs ... otherwise you're not evening out the ratio.
Damp the bass as effectively as possible, while working to retain adequate liveliness in the mids/highs.
Merely wanted to drop a note in appreciation of your content. Didn't intend to add all this, I know you've got this.
All the best
Great work... super valuable that you went thru and measured at each juncture... you know audio folks love to disagree or pontificate about method (I’m not saying it isn’t important) but the results are what matters... and you have certainly improved the response of the room!
Hey John, this was super interesting! Just watched the diffuser build video and I'm glad you put a link to this channel at the end! Cheers!
This is by far the best build video. The waterfall graph is the only thing that matters with these treatments and acoustic panel manufactures never include it in their testimonies. John has a completely square room and made it work with proof. Outstanding!
I have to say your efforts paid off quite well. People may not understand by simply looking at the graphs, but the changes are fairly dramatic for what you can expect.
So, John is basically building a walk-in headphones. Nice!
After watching maybe 100 videos, this is the one that best seems to capture every aspect of acoustic treatment and "sound proofing" in a coherent and easy to understand way. I love the professionalism of Acousitc Fields, but between the sales pitches and abrupt end of each video, I had to watch dozens to get this much information. Great job, and to anyone else poking around, this is a great place to start and get a solid understanding of how sound works in a space.
Very nice step by step and great results. There are times when I want to rip everything out and just start all over again but there are just too many other projects on the go at the moment.
I can't wait. I am so interested in how you finish this room and what speaker design etc. Great Channel!
One of the best videos I ever seen thank you for all the information you are showing us and enjoy your room.
Such a difficult task! Cool to see your tests and the results.
Wow it shows how the decay times is decreeing in your measurements. Well done 👍
Interesting to see the process, Thanks
so glad i discovered you and your channel. its inspiring in so many ways.. thanks
Great video… easy to understand and explained in layman’s terms !!!
Thanks for the information and good advice.
We will listen to a beautiful voice and not disturb the neighbors either.
Your room is sounding pretty good John, good work. Like what I'm working with right now is targeting specific frequencies, more to learn about that for sure. It gets problematic for sure the deeper down the absorbent rabbit hole you go :)
Hey John, Great video! I find your woodworking videos fantastic because I used to be a carpenter and now I'm a sound designer working in film and TV. I used my construction 'skills' (Not so great anymore haha) to build studios and currently on my 5th and last one. I am no physicist but I am in love with acoustics and I do know the fundamentals fairly well, though, like you said it's an extremely complex topic. You mentioned that your room is too small for the waves to bounce around but that isn't true. A 80Hz wave is roughly 14 feet, which explains your RTA readings as well as the harmonics. You can also prove this in your shower, just make a high end to low end sweep with your voice and you'll hear the tub mode pop as you get really low (Mostly a harmonic of a higher frequency but its a fun test).
The trick to stopping modes or standing waves is to cut the frequency off 1/4 into the wave, so a trap that's 3.25ish feet would stop that pesky 80Hz mode, practical? NOPE so to get around this is you find material that soak up the frequencies that are being an issue, Rockwool is great because it is relatively good at soaking up lower end frequencies, at least in its coefficient tests. Though the thicker you make a rockwool panel the more low end it will reduce (but like you said take away the high end). The resonant absorbers that you've made are a great way to save space.
The issue with modes is that only the lower end ones are a problem because they are the ones that fit in smaller rooms and they are the most noticeable, there are so many higher frequency modes in your room but they all are un noticeable as they are too numerous. So the theory that I build into my studios is, use as much rockwool as possible to soak up the low end, then treat the high end with quadradic diffusers. A reason I don't like resonant absorbers is that they are tuned to a specific frequency and any change in the room, like a couch will change what happens and the math gets out of hand.
I'm a really big fan and I hope you take this information well! Great video again John!
I didn't say they won't bounce, I said they don't fit - a 20Hz wave is 56' long. 56' is bigger than 14'.
Not sure why so many people choose to misinterpret what I say.
The room modes are 37hz, 40hz and 70hz - length (slightly more than 14.5'), width (14') and height (8'). You calculate that by doubling the dimension and dividing that into 1130. The first harmonics are 74, 80 and 140.
@@IBuildIt hey John, well what you said is that the frequencies involved don’t fit in the room but they do. Anything over 80Hz fit in that room and would cause problems.
My first thought when I saw the video title was " Why is John making a video about fishing?" . Then I noticed it mentioned acoustics. Interesting topic, thanks for the video. :)
Spacing of the panel off the wall is basically allowing you to get almost the same absorption as if the entire area depth was treated. There is a big misunderstanding going on where many people are claiming that an air gap is better than full depth absorption, when in fact it is the opposite. However, using an air gap can reduce the cost considerably (if you build several panels) while attaining almost the same performance.
The train analogy was a good one.
Thanks, Your explanation is easy to follow.
I use the sofa. Looks amazing John.
Looking forward to your next video! I'm especially interested in how you'll treat the back of the room.
Live sound engineer. Current times mean outdoor venues with power issues meaning portable generators on a budget. Noisy!! Been struggling with building sound enclosures. Reading as much literature as possible and watching TH-cam videos. Glad that I was a drywall metal stud carpenter in my younger days. In some of the literature, I've seen where 25 gauge metal studs are better than wood for sound reduction even with the sound transfer of metal. After hearing you talk about the plywood giving a little (in and out like a speaker cone), maybe that's where a high gauge metal stud would be better than a wood stud, in that it has more give. Just a thought. Carl
P.S. I like how you are working through a problem with no perfect solution. I feel your pain!! LOL
Very interesting ! Great Insights.
Disclaimer, I too am not an expert, but as a music teacher and musician I have done a fair bit of study in the acoustics field. You make great points here, bravo. You mentioned the problems associated with a square room, but almost equally important is the reflection of sound waves from parallel walls. If it is not too late in the progression of your construction, I would build out at least one wall at a slight angle from its opposite wall.
Apparently (from my own research on this) the walls need to be angled by a large amount to have a significant impact. Angling the walls also wastes space, unless they were part of the original room layout - moving an existing wall to angle it is well beyond the scope of what I'm doing in this room.
This isn't necessary if the room is acoustically treated. You will still have standing waves with any room shape. All you do is shift the room moods around.
@@IBuildIt Acoustics literature points out that 10 degrees are the minimum to start seeing effects for angeling parallel surfaces.
you have probably build better acoustic treatment in your room than you’ll find in majority of professional recording studios around the world . well done!
Great video!
In short you can say you don't want the bass to "echo". Like with an empty room you hear the highs echo.
Good luck with getting rid of standing notes with in a 8 foot tall sailing But you do give some really good tips an you do have a really good understanding of how acoustic works
I am not sure if you are using the same equipment you do for the shop videos but the sound from this is very clean, easy to tell that the room is well treated. Hope everything lives up to expectations.
Favorite song: We Rock wool! 😜
Wish I lived near this guy so I could pick his brain. Amazing work.
Listening to your explanation it seems as if this is like speed bumps for low frequencies. This is how I understood your explanation as a layman.
Kind of and I can see where you get that from my train comparison. The treatment is used to pull some of the energy out of the low frequencies, like putting a pillow over someone's face that's screaming at you :)
Thank you for not just making us rely on you habilities to form complex phrases full of subjective interpretation and add some proper measures.
I have 4 bass traps and several panels that I built for my main listening room. I have the bas traps from floor to ceiling in the corners, triangle-shaped and free standing one on top of another. You seem to have gotten good results however. I wanted something quick and easy so I just dampened the hell out of my room :) Edit: some panels are on the sides and I hung two from the ceiling over my listening position.
Audio guy, Musician here. Well done and we'll explained. 😸👍🎶
I always like it when you really sink your teeth into something, like with the clamps. You talk about little else for a while.
For the ultimate in room treatment, cover the walls with rough sawn lumber, cover the ceiling with cork.
Very Cool John... Makes Perfect Sence! lol
Great video, very insparing. 👍
Theater is looking good. I don't know anything about bass traps, but have used dynamat for car stereo installations in the past, of course the purpose is different. My Denon AV receiver has a multipoint EQ that is set up with a microphone, would adding bass dampening via panels improve the curve then, or what if the room already has drywall. Interesting stuff.
Adding panels to reduce the reverb time will always help - you really can't add too many in the typical room.
You're on the right track. But if you want a "warm" room sound but block out bass travel to the exterior I've got one
word for you - Acoustiblok. Hang it like drapes around all of your outer walls - then put up the baffles and panel you
have leaving about an inch airspace. Concrete. The floor is going to be a resonance problem.
This is what I did - I have a metal building behind my house. Half is storage, half is my practice room. The walls are
coated with spray rubber undercoating (the whole building) - seals, helps keep vibration down, minimal soundproofing.
Jam room is built room in a room. Outer walls and divider wall are insulated with rockwool then 2 hanging layers of
Acoustiblok from ceiling (8ft) to floor inside a 2 inch airspace. The inside wall is another layer of rockwool. Foam tape on
all studs including frame to floor. 5/8 plywood walls, floor and ceiling. Floor has a layer of Acoustiblok between the
concrete and a layer of plywood. I did this after the fact when I found out that carpet alone wasn't gonna do the job.
Doubled door entry with both doors layered. Building has 12ft side walls and 14ft peak. Ceiling (or attic floor) has
Acoustiblok, rockwool, Acoustiblok between ceiling studs then plywood on top. Used as extra storage space in building.
Interior is cover with sound absorbing foam with foam corner bass traps. I'm a bass player so If I don't rumble no one
else will that comes to jam. I wanted as "dead" a room as possible so it doesn't bother neighbors.
The most vulnerable part is the entry. Testing at the door is 47db with a full band inside at a db level of 147!
20 ft away - nothing. My house 40ft away. Nearest neighbor to building 90ft. Mission accomplished!
Nice room you've got going John. But if you're looking to keep bass travel down you'll definitely need to cover
that concrete and ceiling and some corner traps which a panel across the corner about 12" wide with holes half
the size you have on the others and then an 18" wide panel with the same size may create a catch in the corners for you.
Currently helping my brother build a studio and that's an idea out of many we've had to keep the main room "warm" and "live'
for recording.
Anyone interested in keeping sound travel down should definitely check out Acoustiblok. Good product and very
helpful people there.
PS Putting Acoustiblok and a layer of plywood under the carpet made a 26db difference.
For some reason, I'm envisioning you recreating the old Maxell "Blown Away" commercial, the one with the guy in the chair getting "blown away" by the amazing hi fidelity of the cassette tape (amazing that was in 1979, damn I'm old).
Cassettes were great, I think I still have a few of the ones I had back in high school (early 80's) here somewhere. Nowadays everything is on my computer - everything else is too much work and that's especially true for vinyl.
@@IBuildIt My Father-in-law collects LP's so we have about 10K of them in our garage, he has ~50K 55's and 78's at his house.
That was Pete Murphy from Bauhaus.
If you don't want to drill all those holes, I hear you can also put up panels with slits between them. Like slim vertical boards with space between them.
Would love to see a tour of your house with all the before and after photos. That would make an amazing video!
"Hole-y Diffuser" is my favorite Dio album.
"Hole-y Diffuser, Batman" !
the panels with the holes look great
Great video! One suggestion: use hemp wool instead of glass fiber! Same effect but doesn't kill you slowly when breathing it in! You can use wood fiber as a substitute for rock wool, but rock wool isn't as deadly as glass fiber (still not great to breath the stuff) and its harder to come by in the US.
If fiberglass killed you, millions would die each year. It's been used as insulation in houses and other buildings for nearly 100 years.
fiberglass stays in your lungs, but Rock wool doesnt over time
Could you try a Helmholtz resonator at 40hz to try to fight those modes? I have seen some built that sit in the corner and look like a small trash can.
This is so interesting.
The one thing that this video gets across well is just how large you really need to go to get significant taming of modes as low as 40hz. Most videos have no measurments and make exagerated claims as to how big a difference a couple of panels will make to the bass response
What a champion effort.
Damn good video, you explained your methods, and showed the results at each stage. Very informative and 'real world'.
your frequency graphs look like it made a pretty big difference in the low end. thanks my room def needs help. im going to use your holy bass diffuser trick. 🍻
Bass trap? Obviously a fish catching device.
very interesting stuff. didn't know about any of this.
Something you don't mention, and most people don't understand, is that most sound you hear indoors is from reflections. You hear the initial sound from the speakers, and then 100x as much sound being reflected off of surfaces as it bounces at 700-ish mph back and forth, reducing in strength every bounce. Your efforts are redirecting or reducing the energy of those reflections, and therefore the amount of times they continue to come back to your ears at a significant level. What's left over is easier to listen to, and more accurate to the original recording in the case of music.
And good work sir.
I am curious about how well your plywood wall membrane will work for low frequency capture and /or diffusion. Whisper wall uses a similar approach, but the material they use is much lighter than wood. To capture anything below 800Hz, I would suggest leaving gaps in the wall panels along the rear wall, that are covered with acoustically transparent cloth. If possible I would have these openings run from floor to ceiling and be at least 2' wide. This should work as a bass trap down to about 80Hz, and diffuse a portion of the the frequencies below that.
*Edit- My apologies, It would have helped if I had finished the video before writing my comment. You pretty much did what I was suggesting, but you placed two on the front wall and have a semi-reflective surface on the front of the trap. I like how you approached it though.
I am personally designing / building my "Dream" wood workshop. I have been down the rabbit hole of sound in an effort to to reduce the sound that is inherent to a shop and also for music. I can listen to this video and without question "hear" that the room is "treated" ( it sounds good, and I am sure will only get better ) and looking back at your shop videos its now amusing to watch one of your videos from say 2015 vs your more recent ones. Could you maybe do a video showing / explaining the treatments you have in place in the shop? GREAT VIDEO!!
glenn from specter media group would love that you included frequency graphs as evidence. yeah science. 🍻
John really interesting stuf. And although you are not an expert its so worthy for us to see how experiments can work out. Subd!
Nice video and measurements. You should try to put sack with sand in corners -they are good and not expensive bass traps.
First thing is you need speakers that produce the sound, you need an equalizer, and a true microphone to measure the sound waves, I would suggest that instead of trying to make the room conform to your speakers, I would make the speakers conform to the room by proper equalization, lot less work and better results. I would suggest instead of spending money on wood I would spend the money on a Klipsh horn speaker, or if you like room shaking bass a set Electro voice 18 to 30 inch bass speakers. Then use stuff like mirrors and carpeting in your room with the true mike and equalizer to set up the room, you will also need a decibel meter to set up the separate frequencies. Used to do this years ago when I was younger, set up one disco with Electro Voice speakers and told him do not go past 1 watt, you may deafen people, on opening night he went past one watt and shook the color show glass box light out of the floor. Gave me a call the next day and said you where not kidding, I told him that was my job. And yes people no matter what they say today about sound, what we know today will be obsolete tomorrow. Me I will stay with the mighty Klipsh Horns for real sound, and Electro Voice for speakers that will bring down the walls of your house. There was another speaker I believe they where B&W that gave amazing sound but you needed 1200 watts of power to power up that speaker.
Great story... love hear things like that!
However you're discussing the 𝙛𝙧𝙚𝙦𝙪𝙚𝙣𝙘𝙮 domain,... here John is addressing the energy in the 𝙩𝙞𝙢𝙚 domain. He's damping the bass ringing in the room.
Try lead flashing sandwiched between sheets of OSB and drywall. Lead is ideal because it's thin, heavy and soft at the same time, so it absorbs maximum energy. It's the secret ingredient in a lot of recording studios.
I can see how this can work in theory. Do you have any empirical data?
@@manamimnm My windowless wall is in fact a garage door (brick and concrete town house). The other side is a busy city street. I insulated the inside of the door as described: osb-lead-osb-dw. I sealed the edges of every layer to the floor, ceiling and walls, and sealed any seams, to prevent air leaks. Leaks = noise.
I can't hear the outside noise at all anymore, and mics aren't picking up anything either. The only exception is construction works causing vibrations coming through the floor.
Really thanks. Very usefull your explication. Thanks
P-R-O-J-E-C-T-O-R I know TV's are big enough these days, but if that room isn't screaming for a projector, not sure one ever will.
You should try to move your sitting position a bit forward or backwards from the center. The center of a rectangle room is bad to start with and probably worse in a square room. I tend to move backwards from center in smaller rooms because speakers need room to breath, but I'm sure you know that you can't get too close to the back wall, or it will open up a bunch more problems.
Great content thanks
All measurements and techno details aside are you pleased with how it is working/sounding to the naked ear? It looks great by the way...
I can hear the improvements, but I'm a long way from finished.
Hey John, you might want to put a sheet of thin plastic film over the fiberglass before putting the cloth and slats on. Failure to do this with overhead treatment will allow the very fine glass particles to rain down (I'm not talking downpour here) and you will see this depositing on your furniture - consider too that you will also be breathing this in while using the room.
It's ridiculous to think that enough small particles will get through a tightly woven cloth to be any significant problem.
Tell me, are you a proponent of wearing a cloth mask to stop a virus and get unnaturally terrified when you see someone who isn't wearing one coming toward you?
If so, can you see the contradiction?
@@IBuildIt OK breathing may not be so much of a concern. I am referencing discussions I had on John Sayers Forum sometime ago and we were more concerned with this dust building up over time in the faders of a mixing console and other equipment. I realize you're not building a music studio, so maybe it's not much of a concern. I just thought I'd mention it for consideration.
As for confrontations with mask less people - no I don't panic, happens almost daily here in rural Switzerland - though I would get upset if they coughed on me.
@@sunpointstudio4472 Ah - a forum - the birthplace of the art of making mountains out of molehills.
On a possible list of considerations when doing something like this, the one that concerns the amount of dust that's able to make it through the fabric should be on the last page at the bottom. It is a completely insignificant factor and anyone who's done this knows that.
This is really interesting, although I don't understand a lot of it.
Little know fact, John is the guy from the front of the old Maxell tapes.
lol..."Is it live? Or is it Maxell?"
I know next to nothing about this subject but now I know a bit more. 😀
John, I’m wanting to learn more about acoustics like you did.
What literature and resources can you recommend? Thank you.
Thanks John
It's a challenging room the way you describe it. Graphs are showing progress though.
Rooms need to get up in 30' x 20' with 12' ceiling range before they start to stop being challenging for bass. And you don't find rooms like that in the typical house these days, unless your house also used to be a church :D
@@IBuildIt lol
Small room acoustics is a secondary professional interest for me. Most of your room treatments are good, but I was surprised to see the TV on the wall at the end. You need the Diffusers on the rear wall not front for best imaging. Read up on mirror points, Haas effect, etc. if you had more Diffusers where the TV is, that would be a good design for the rear wall. From what I can see on the brief plots, you did a good job on reducing bass modes. A waterfall plot shows this better than the spectrogram in my opinion. I have never built a QRD, for work I just buy them. You might consider improving your design with a scaled version in each cell to extend the range higher. I have seen plans for doing that with strips of MDF.
I need the TV and from what I've learned about this having it there behind and between the speakers is the single best place in the room for it.
The rear wall will have more diffusers with more bass traps, but it also has a doorway that needs to be dealt with. After the build in stuff is all done, I'll make some free standing absorbers for early reflections and additional treatment.
Me: I put an old patched subwoofer on my television to get something better
J.H.: Bass traps #6, it's a work in progress
Спасибо тебе большое мужик. Очень полезное видео, все понятно. Удачи с работой!!!
Fascinating
What’s the thickness of the plywood you used for the diaphragmatic absorber, and what would you suppose would be the affect of using a thicker plywood? Thinner?
Nice channel 👍
Wow. That’s amazing. Are you Canadian ?
- Nick from Toronto
Thanks for the video. I cringe when I see folks use the cheap studio foam and claim "we are now sound proofed, neighbors can no longer hear us" :( I'd love to know how you are treating isolation though, your thoughts on tube/tuned traps, and if you've tried making waterfall graph (which are my go to personally). Also, have you considered shortening one wall to avoid the perfect square, or angling it slightly.
Isolation isn't an issue for me. It's quiet where I live and my neighbours are far enough away that any noise I make won't bother them.
As for tuned traps, they need to be huge to work at really low frequencies and also need to be in the right place to work well.
Angling the walls does very little, from what I understand. They'd need to be really angled to make an improvement.
The charts I posted are spectrograms and they are just like looking at a waterfall plot from above.
What if I built a free standing panels, in a roundish cubicle around my desk. No corners. Leave gaps so pressure can escape. A cloud above my desk. With gap. So pressure again can escape. So my room can remain a live room, it’s all wood. But when I mix, I pull the absorbing panels around me, in a circle ⭕️
Have you done any work on reducing shop noise?
What diagram you used to get the circles for cut out you got
Very interesting. What. program and test mic and sound source are you using? I use a homemade dodecahedron speaker and an Earthworks M30 mic. Just FYI your room is too small to develop a true statistical reverberant field. You are dealing with cumulative spectral decay. And yes you have a massive amount of modes in the small room plus flutter echoes. Some of you assertions are not 100% correct but close enough. You might consider a Helmholtz resonator trap in each corner at the fundamental freq of the lowest room modes. You also need add diffusion to the rear wall. You should get tbe book Master Handbook of Acoustics by Alton F. Everest. Keep it up and i enjoyed the vid
I never said I expected a diffuse sound field in a room this size. What I did say was the goal is to get the reverb time as even as possible. "Aiming for" and "expecting to hit" are two different things.
And since I'm not an expert or even pretending to be one, like I said in the video, it's to be expected that my assertions wouldn't be 100% correct.
I'm using a Umik-1 and REW to do the measurements. Speakers are Elac's.
Does the TV panel add any bad reflective noise? And would a projector screen be acoustically transparent like cloth? Very interesting video I love the new channel addition to your lineup.
Being behind and between the speakers is about the best place for it, since it's not getting a lot of direct sound. Probably won't be a problem big enough to solve.
Did you have those panels mounted with caulk? Pretty much made them fully isolated.
And how did you deal with fiber glass and rockwool dust in the air?
You've mentioned the walls - sides, front and back - and ceiling; but, been quiet about the floor - so is that tile for echo or carpet or futons and pillows tossed about for additional careful sound throttling? Presumably, to be addressed in another episode (I'll be patient).
I'll eventually do wood on the floor, but in the meantime have thin carpet tiles. Floor is generally not treated, especially when you can do the full ceiling.
@@IBuildIt I've attempted a little additional research into acoustic floor treatment this morning too and what I've come up with so far is that that is usually left to dust balls and pet shed hair accumulating naturally - but that's just from sweeping, I vacuum later today.
Can you not use an equaliser, or something similar, to drop that 37-40Hz range?
what is wrong with using an equalizer and speaker placement to achieve this? that is what I have done in the past to even the sound to the room.
I love music, play guitar and piano, but would never claim to be a true audiophile; probably because I've destroyed my hearing trying to imitate Alex Lifeson :)
I only mention this to say that even if I couldn't tell the difference in the sound at all, it looks cool as hell!
I certainly don't consider myself an audiophile, but I do like listening to music. And a well treated room will help greatly if you have hearing loss.
How about a Helmholz Resonator as absorber tuned to 37 Hz? This could help with your Room modes
I think you should put Admiral Ackbar in the thumbnail... 😉
Maybe I should have worn my Vader helmet while filming :)
I totally transformed my square room’s horrible low-freq sound by doing it via the CHINA method….cheaper, simpler, most effective method i hv encountered.
No need to buy lots of fiberglass, rockwool and no need to fill the room with such a huge qty of panellings.
In my country, we call it “plaster ceiling” which is the American drywall done on the ceiling with a huge airspace behind it.
In short, simply create a slanting, fake ceiling (from drywall material) so that your entire ceiling is sloping in any direction. It will totally transform and normalize the horrible low-freq behaviour of any smallish squarish room.
If you dont wanna slope the ceiling, then you can slope/cant/slant ONE wall…any wall.
The results are amazing and the room’s size doesnt diminish much while looking so clean.
The above were done to 2 highly problematic videoconferencing rooms during the Covid lockdown as taught by a China-based German acoustics specialist, and he simply calls it the China method….clever, efficient, cost-effective…thinking out of the box👍
Wow! Interesting! Can you share photos of the rooms?
@@saadulislam1
Gimme your email address and I will send you a pic of it.