This is probably one of the best if not the best channel about room acoustics ever. Everything you need to know explained in a very simple but effective way. No need to scroll and search in hundreds of forum posts. This is gold! Keep up. Highly appreciated.
He’s for sure been the most helpful..it’s hard to listen to most engineers speak …..just his tone sounds like his logic is undeniable and his theories absolute and u dare not challenge his word
With a 4-inch thick slab of acoustic foam and no air gap, the Porous Absorption Calculator says absorption is down to 80% at around 400hz. If you split the foam into alternating 2-inch slabs in a checkboard pattern, you can get different air gap depths between adjacent slabs. With a 4-inch air gap, 80% absorption drops down to 300hz, but there's an unwanted dip at around 1200hz. With a 6-inch air gap, 80% absorption drops to 200hz with a dip at 900hz, but there's a secondary 100% absorption peak at 1200hz. With a checkerboard array of 2-inch slabs and an upper slab air gap of 4-inches, seems like the 900hz and 1200hz dips would be compensated by the absorption peak of the complementary slab. That would give you an octave lower 80% absorption frequency while cutting the foam thickness in half.
One more note on open-air gapping. I read a GIK mounting test using a 4" rockwool panel where one panel was tested flat on the wall and the other was tested with a 3" open-air gap. The 3" air gap did get a small boost in absorption coefficient starting from 160 Hz and down, but started to create an absorption coefficient loss starting from 630 Hz and up. So no matter what, you don't get something for nothing. It's a tradeoff. Again in this situation though, it's still better to just use a 6" panel over a 4" panel open-air gapped.
Great videos. Most of it actually usable for home listening rooms also. I don't want to build studio but I need to treat my listening room in order to achieve balanced and natural sounding sweet spot.
@Laura Brown stop outside noise doesn't do much to your inside room acoustics itself - absorption and reflection (keep noise out) aren't the same and many stuff like Molton just *reflects* high frequencies, for bass it don't do anything at all
Jesco! this answers my question from your last video. I had built panels last year that were only 4" thick and after taking your courses I learned that they should be 6". Any new panels I built would be 6" but I already invested time and money in the 4" panels, so I ran the absorber calculator and figured out that I could get slightly better response with a 1" gap. It worked perfectly and I noticed a difference. I also used this same approach to calculate the placement of freestanding temporary panels. The only door in my room is in a corner and bass tends to build up there so I placed a 6" broadband absorber during mixing sessions. I used the technique to calculate the optimal placement and air gap to the wall for the temp panel then I placed tape on the floor so I can quickly place it in the same spot. Thanks for the advice !
You have authentic depth of knowledge, and you're quite skilled at conveying complex ideas clearly. This was a real treat to watch, and the best I would ever expect to find for free. Thanks so much for sharing so generously.
I’m curious, o guess we’re assuming the gap is against Sheetrock?Would the measurements change if the wall was treated? For example: if I had a room that was treated with 2 inch, then added 6 inch with 6 inch gap in various spots as needed better somehow? Rather than just having a gap with sheet rock.
Very interesting, so if I understand the conclusion at the end correctly, it would be beneficial to have an air gap (all be it not more than the core size), but if you have the space and resources it would still be better to just have a thicker absorption panel that would take up the same space (panel + gap). I did elevate some of my wall panels with acoustic foam on the sides of some tiles (so it has a gap to the wall inside but doesn't have open spaces on the side). But next treatment I will just get foam sheets to just have a thicker panel to elevate them. Thanks a lot! Great channel!
Soon after I wonder about an aspect of room treatment I get recommended a video where you cover the topic. It's invaluable what you're doing for us newbies of home studio setups. Thanks a million
Excellent video. Clear and concise backed by scientific principles. You obviously know exactly what you're talking about. I'm an immediate disciple. Many thanks.
Super informative video, thanks for that. Does this mean that I can have air gaps for my corner bass traps instead of super chunks, and the absorption may be the same or even better?
Some acoustic panels come with a solid backing material such as plywood. In this case I assume that an air gap does nothing, since the wood back acts like a wall. Correct?
most of the low frequencies don't really care about that, they go through - that is why you see bass traps reducing the amplitude of bass frequencies while having a hard outer shell (and sometimes hard inner spacers with air gap). Hope this makes sense. I think for mid frequencies it might be rather true though. Also, real life often overwrites these nice charts, these are just guidelines.
Just discovered your channel….. This simple formula you described is priceless!. I was always told it can be a good idea to leave a small gap behind hung panels, but I never knew there was a specific formula behind getting the best results. Great stuff !! 😉👍
I have reasons for needing the air gap other than performance - at least two of my planned absorber positions have light switches which I need access to. Using thicker panels is pretty much out of the question. What I don't see a lot of advice about is how to actually mount panels (in my case GIK) with an air gap. I know GIK have brackets for ceiling clouds, but I don't know if they're the best or easiest option for wall mounting. Any tips would be appreciated!
I have a 10cm thick ceiling absorber preventing me from early reflection at listening spot. Does this mean I have to hang this not more than 10cm from the ceiling to avoid the non-effectiveness in the lower mids? Thank you for all this incredible wisdom you share here with us.
I am glad I saw this. I have been thinking of making a diffusor by hanging a variety of panels of dry wall of a variety of sizes at a variety of distances from the ceiling. I know there is nothing new under the sun and somebody somewhere must have thought of the same thing. I wondering if a 1 meter by 2 meter panel of drywall say 3 cm from the ceiling might not end up acting as a bit of a bass trap?
I heard air gap is important between window and acrylic window insert. Also I'm planning to use 2 exterior doors with space in between for our home studio.
How would that work if the panel is put in a corner? (Meaning the air gap would be triangular). Does the same rules apply in terms of ratio? Keep up the good content!
Was debating between the whole back wall with all 3” Safe and Sound and pull grill cloth down over or making panels. I guess your recommendation would be to make panels. It’s a heavy bass room.
The absorber should be place as close as possible to the 1/4 wavelength position, where the amplitude is greatest and the absorption most effective. Longer wavelengths have 1/4 wavelengths farther from the wall, so the absorber must be moved farther from the wall to be effective, compared with shorter wavelengths. Please correct me if I am wrong.
So does this mean you want to have varying air gap depths to cover that dip in the midrange? Adding some blocks of absorber on the back in air gap, to get the best of both the airgap *and* the double depth of absorber but without the cost of having a double depth of absorber over the whole panel? Or perhaps alternating airgap and full depth panels (again to reduce the cost of absorber).
Having an air gap at all is a debatable topic. The issue of panel air gaps center around having an "open" air gap vs. a "sealed" air gap between the panel. Some have said that an open air gap may not do much acoustically. Looks like more numerical data is needed in the open vs. sealed debate. The documentation for the Porous Absorber Calculator does not make it clear whether the air gap measurement is based on open or sealed.
When you switch that calculator to "random incidence", that effect totally disappears and then it's just deeper = better. Now I'm wondering if I should back-fill my absorbers for more even absorption. EDIT: For treating modal frequencies, 0 degrees incidence works since those standing waves hit the wall dead on in a rectangular room. So it's better to use the material to cover more area if making it thicker doesn't increase bass absorption.
Using the largest depth with a single layer over a larger area... But doubling and triple layering the centers or targeting first incidents etc could result in best results... I have those IKEA square shelves with the open back.. Covered and stuffed and off the wall a few inches. With stuff in them.. Books.. Guitar pedals. Batteries.. A coffee tub.. Surprisingly good compromise.
I bought some higher quality 1” foam (should have bought 2”) but I’m gluing to 3/8” plywood so I can move, reposition or remove them. I was going to space off the wall around 1”, but since the souldwaves will not pass any deeper in the foam before it bounces off the plywood, I won’t get anything from spacing off the wall. Correct? My only thought is some sound waves bouncing behind then bouncing between the wall and plywood backer. Any truth to that? My studio base for guitar with Marshall amplifiers is 12x 8 with 8’ ceiling. My space is small. Carpeted floor.
Just out of Curiosity, is there any benefit observed if the panel is mounted like a wedge, for example, closest to the speaker has some or no air gap, with furthest away having the opposite property?
i have watched about 20 of your videos since saturday night and feel transformed. i have learned essential things and really appreciate your videos and advice and how well structured all of it is communicated. so, i am planning to get into building absorbers and bass traps (and maybe diffusors later, if i still got the need and motivation). atm i am calculating the air gap behind the panels, but i have an important questions: do i also need an air gap behind the bass traps? and if so, does the gap have to be all around the bass trap or just in the corner? i thought about building a standing plate for a bass trap and started wondering, if it would be neccessary to have it be a few centimeters wider all around.
Great explanation! I have a related question... what would be the difference in having an absorption panel close/against the wall as opposed to having them hanging on a stand closer to the listening position, and say 3 feet away from left and right wall?
What about putting the panel with a gap from the wall, but filling the gap with foam, in order to capture those mid frequencies? In other words, wall, foam, panel...?
Hi, i plan to rent a 100 sqm room as a dance studio ( 3.5 meter height ) , i will be using the cement ceiling for ceiling mounts for my hoops/poles . Anyway, the tenant beside me will be a 24 hr CALL CENTER , we still don’t have a partition between us ( on the partition i plan to install the dance mirror ) . For the partition, the owner will install a DOUBLE wall hardiflex . Will that be enough to deaden or block the sound for both rooms? A supplier suggested to : Insert 3 or 4 INCHES ROCKWOOL fiber in between the hardiflex, then on my side - place the MASS LOADED VINYL ROLL on top of the hardiflex acoustic, ( there might be a gap in between this and the actual wall where i will place the mirror , they suggested that instead of using plywood for the mirror to be place, i should use SILICATE BOARD as a replacement, then finally the mirror. Not sure if there is a more cost effective way for this . Thanks your reply will be much appreciated
I’ve just found your channel & this excellent video on this subject. I have a question which is I am about to install side wall panels, & I’m trying to figure out the first/ second reflection points. I’ve heard a lot about using the mirror trick, is this something you would recommend, or would you have a other suggestion?
I am thinking in using now, silk screening mesh fabric to cover my panels. It's made of nylon, stretches very well, and allows the sound to go inside the rockwool 100% letting it do its job completely well, the way rockwool is supposed to work. It is not expensive if bought by the roll at Walmart. Using the correct opening, won't allow the tiny pieces of rockwool get out of the panel, that are really bad if you breath them. What do you think? .
Ok, so now after watching the GIK Acoustics video on Air Gaps, it's pretty clear now that air gapping is really not a good idea unless you are doing extensive frequency testing and you know exactly what you are doing. If you are trying to float a 2" panel an inch or two off of the wall, then it's better to just use a 4" panel flat on the wall. And if you feel like you need to float a 4" panel off of the wall, then it's better to move up to a 6" panel flat on the wall. It appears that... yes, a "sealed" air gap is better than a open air gap, and an open air gap can make your situation worse if you aren't doing serious frequency measuring. Performance-wise it's better to just use a thicker panel flat on the wall over a thinner panel with an open air gap. It also looks like most GIK panels come with an air gap in the back portion of the frame, but it's also sealed with an acoustic cloth cover. Also in smaller rooms, it's almost automatic that you should be using 4" thick panels instead of 2" panels.
This may be obvious to some, but misleading for others. When you state the depth of the absorption material in your calculations I assume this means the material itself, not the depth of the frame of the panel. For an example some of my panels are 3.25 inches deep, but the absorption material is at the front away from the wall and is only 2 inches deep. That should mean that material is already 1.25 inches away from the wall and close to the optimal equi-distance from the wall as the depth of the absorption. Were panels manufactured with the panel frames twice the depth of the absorbent material there would be no need to hang panels for optimal absorption. Please correct me if I have misunderstood.
Great video, thank you. To counteract the dip in mid-range frequency absorption with a large gap, would it be prudent to put an additional layer of absorption on the wall (so effectively double layering the panels, one against the wall, one a few inches off)?
Depends on the room really. Maybe you don’t want less mid and if so then just make the absorption thick and thin but no inbetween or add bass traps and those ugly useless foam because that pretty much only touches high frequencies
Many traps are 10cm deep and placed wall to ceiling or wall to wall which means the depth from the corner angle to the trap is deeper than the trap. Is this wrong? It seems to be common practice
Do the cuts and shapes of acoustic foams actually make any difference at all? For eg: compared to a thick block of 2 inch acoustic foam , is a 2 inch pyramid foam better or worse? Or is it a marketing strategy to make less amount of foam more appealing by saying : more cuts means more surface area means more absorption etc?
it seems the graph with the air gap has more comb filtering going on, though. as much as you may save a few dollars by using an air gap, wouldn't it be better to have a flatter dampening/absorption curve, unless the peaks and valleys are precisely opposite what you're attempting to "fix"?
When you say air gap does that mean the wood frame away from the wall you can stick your hand behind it gap or are you building a larger frame including that space behind the panel as in a 2-inch panel would need a 4" frame or is it just a 2" panel with a 2" spacer leaving a 2" see-through Gap behind the absorber?
Great video thx for sharing. In this case I could away with flat panel bass traps instead of triangle 🔺️by leaving space. 8 inches panel and leaving 8 inches or more I'll be able to achieve that. Bast explained thx again.
Another great video. I'm wondering how things would be affected by storing things in the air gap. I use my space primarily for mixing but also to record drums a lot and sometimes rehearse too, so space management is important and I have a lot of gear to store (multiple drum kits...). So I have a potentially crazy idea of putting floor to ceiling storage on the back wall (50cm deep) with various drums, stands, mics, cables etc and putting a "wall" of moveable gobos essentially in front of that. Would those panels then need to be 50cm deep themselves to have any effect? Would they even do anything to low end if there is stuff of various shapes and sizes behind them?
Great video as always. Question: Is there an upper limit on rockwool thickness when it comes to bass trapping? For example, let's say you have a room big enough where you can pack a full 1m (!) of rockwool against the walls. Is the bass even going to get through that much material or are you just wasting rockwool at that poing? Thanks as always for the great videos.
I'd simulate it in the absorption sim Jesco showed here. It's vital to enter the Rockwool characteristics in the variables. Or, you can split it like he suggested, ie. .5m material with .5m gap. Or just go for it ... put up a full 1m depth. Typically the thicker the velocity trap, the less dense the material requirements are.
@@FOH3663 Good tip! I should have mentioned that I did this and that's what the simulator reported (after about .5m there is very little difference). The only part I couldn't figure out was the flow resistivity for Rockwool RWA-45. From what I have seen, it's right around 10k (the default value at AcousticModeling.com) but that was extrapolated data from a random acoustics forum, not an official Rockwool spec sheet. I'm not sure they've posted that information for RWA-45. Anyway thanks for your good response!
@@LeoMakes You probably got it sorted by now, but it mainly depends on how low your speakers extend and how dense the material you're using is. So it could be worth it if: a) The insulation you're using has very low flow resistivity (1000-5000) b) Your speakers are producing sound in the 20-40hz range If the flow resistivity is high, you won't get much beyond 300-500mm thickness. If your speakers taper off at 50hz, there's no point anyway because the main absorption increase is to frequencies below that.
Good explanation of why this occurs. But one question: would you not want less midrange absorption? Isn't the purpose to reduce LF frequency while preserving mid and high source content? I've read pros and cons to broadband absorbers for this reason. Second, thanks for the comment on distinguishing between velocity v pressure; could you do a short vid elaborating on this dynamic in application of treatment?
The blip he demonstrated with the simulation isn't "preserving mid and high content". He was simply demonstrating the effects of spacing. To retain mid freqs and upward, you'd need slats, or Visqueen faced traps... that way the absorption is strongly weighted to the LF.
Hi Jesco, I've seen this on an acoustic website and it's completely thrown me re the gap behind a panel. Can you throw any light on this? NWAA Labs, Inc 2017 ASA NOLA Absorption Myth: Wall mounted panels that are spaced off of the walls will increase their low frequency absorption as the space behind increases. Fact: This is only partially true. The low frequency absorption only increases when the spacing from the wall does not exceed 1 inch. The effect disappears after 1 inch. This only applies to unimpeded airspace.
Did I get this right?… The green line representing the sound reduction of a gap less 100mm panel has a far more linear response with slightly wider frequency absorption range in the low end? If so, I feel the cost of the extra 50mm insulation is worth it. I’ve chosen to go with a 100mm framed panel with 60mm depth of a more semi- rigid mineral wool board with 40mm of a less rigid lower density mineral wool board facing it.
Amazing, really - thank for the session on what to be thinking about before you start hanging your absorption panels..(I was just in the process of doing this) ...and thank you for the valuable set up procedure on how to hear the sweet spot for your speaker placement, I was able to understand the process and it gave me more of an insight on what I should have been focusing on - Thank you Acoustic Insider!
Hi, thanks for your videos, they are great! A shot question I have been pondering on... Is there anything to be gained mounting two thinner panels with a gap between them an then a gap to the wall? Or maybe a the second up against the wall...
Just a question: how to know how much of absorbtion you need in a specific room? how to know how much you want to kill in the spectrum, and not only where?
Also fellow Mitmensch mit male-pattern baldness wollt ich nur mal sagen: sieht rasiert richtig gut aus ;)
3 ปีที่แล้ว +1
Great channel, subbed and checking all your other videos :) I have a question though, going to build new panels soon, (200mm depth cotton wool) but i'm never quite sure which density would suit my needs. Any info on that ?
I just came across this video, what an excellent explanation thank you! I have 1 follow up question, so for example assuming a 2" sound absorbing panel and a 2" air gap, would a 2" thick Rockwool inside of a 4" deep frame, mounted flush to the wall, still be the same as a 2" deep panel, mounted 2" off of the wall?
Using the Porous Absorber Calculator at the acousticmodelling link in the video, the half-wave dip in absorption you point out is much less of a problem when the calculator's Random Incidence option is checked. Does this imply that using pyramidal or triangular-ridged acoustic absorption foam is a better choice than flat-surfaced foam for deep air gaps?
great videl man! I'm wondering what the difference would be between just placing the panel further from the wall vs kind of making the frame of the panel deeper so that you effectively create a closed air pocket. I've heard that, that's how you should actually do it, but I was never able to test and compare both versions. what do you think?
Good video and the PDF was an interesting read. My studio is visually a mess but sonically I'm delighted. Gradually I am tidying the room but the question is, how much harm will tidying the room do to the acoustics? I'm seriously considering putting up drapes to simply hide the cluttered shelves! 😀
Curtains will over the shelves will absorb too much high frequencies. Would be better off just moving all the shelves to another room or a storage cupboard.
Great video, thank you! To-the-point, and explained the 1-to-1 ratio of thickness to air gap very clearly. I am currently about to build acoustic panels with 3.5” thick mineral wool insulation, so I’ll be planning on building stands for those panels so that they sit 3.5” away from the wall. I know it’s not 6 inches thick (which would be most ideal), but I also don’t have a lot of room for 6 inch thick panels in my home theater testing room that I’m building for my own channel. Not the most ideal, but better than no panels at all. 😁🤘 Thanks again! You have a new subscriber!
Hi! Would I be able to use some clips from this video in my own video about building out my own DIY acoustic panels? No audio - just me talking over some short clips from this video, since I want people to know where I got the science behind it. I reference this video a few times, so hopefully it’ll get more views too! Thanks! 😁
How does this work with corners? the air gap will obviously be rectangular in shape... I'm sure it's fine since that is the way most people cover their corners but I'm still curious
Thank you! Great presentation. Question: we are getting repetitive bass sounds...day and night constantly from neighbors...! We have dual pane windows and dampers. Could bass be traveling via our plumbing? We love music...but what can we do on the entire length of one side of the house??? We live on a corner and basically have six neighbors. Echo effect probably plays a role? Any suggestions welcomed. Jim
quick question: Is 300mm depth of absorber better or 150mm with 150mm air gap? if I type it into the calculator the curves are nearly the same, only the air gap variant has some dips and the other curve is like a radius.
Thanks for the video. Is it reasonable to substitute "home theatre" for studio with all this info and setup? I'm expecting a home theatre is at best attempting to emulate / reflect the same sort of acoustics they had when creating the audio in the studio when they produced the audio tracks. Cheers, David
Thanks for your awesome content! Very well explained and easy to digest even not having a lot of upfront knowledge. Is this (in a more moderate way) also applicable to living rooms where you listens to music and want to treat the room? I‘m thinking about the wall behind the speakers and basically building a big wooden frame with Pamela’s you find in centralized concert rooms and put absorption material behind sand possibly an airspace. In the living room I‘d not make this deepen than 10cm though as it would otherwise interfere to much with the room and it‘s usage as a living room
Really interesting video, thanks for the calculator! Would be keen to understand if it is possible to do similar measurements with a flat panel in a corner where the depth is then not just a fixed amount, instead deeper in the middle than the edges.
hi , thanks alot for your help , i checked the site and i have a question , what if we use 2 layers of 4 inch panels each one with 4 inch air gap ? does it work ?
Hi dear friend. Let me ask you a question please upon the vital air gap between the wall and the rock wool. Lets say I use 20cm deep rockwool. If i build a 30cm deep frame and put the rockwool onto the front 20cm depth (with dividers where the rockwool will sit)... that will leave me with 10cm free air gap on behind. Ok? When placed on the wall there will be no visible air gap. But actually inside I will still have the 10cm free air gap depth. Well... is that considered as efficient air gap for the best possible bass absorption, while there will be no air flow from the outside? My question is just for aesthetics. I prefer panels that sit flush to the wall instead of gaps. Thank you.
You have a very optimistic view of how these air gaps work. The models in that absorption calculator assume that the air gap is enclosed, and that all of the sound is therefore funneled into a wall and back through the absorber. But that isn't the case when you're talking about air gaps behind a mounted panel, this gap is not enclosed. So a good amount of the sound (especially from the outer 50% of the panel) will not make it back through the absorber, but instead spill out from around the unenclosed air gap. If you wanted this to work like it does in the models, you would need to build that air gap into the panels themselves, so that they're enclosed by a rigid material.
I am gonna test it out, but on that "Absorber Calculator" document page is stated : "This calculator estimates the absorption coefficient of a porous aborbent in front of a rigid backing (such as a solid wall) with an optional air gap between the absorbent and the backing. Up to two absorbers can be modelled at once." There is no statement about a need of the airgap to be anyhow enclosed.. go figure
@@odalv7278 Yeah I've tested it myself, there's no question that an airgap does improve performance, it's just not as drastic as the model predicts (for the reason I outlined). So when he says 'you can leave a 3" gap and effectively get the absorption of a 6" panel', that's not true. You'll get some improvement, but it'll only be about 20-50% as pronounced as the model predicts.
If I make my panels 6inches core, how much fiber glass I need to put in the panel? What thickness of fiber glass should I use? I have 2.5 inches fiber glass. Is that useful?
question. I built a bunch 12" Deep* skyline diffusers. 2 foot x 2 foot. they're big and heavy. 2/3" thick plywood would the same principle apply to spacing them from the wall as well?
So am I to understand that corner base traps will work better if you only put say 3 inch of rigid paneling (I'm thinking roxul rockboard) in front of the corner and leave the corner per se open/empty?
This is probably one of the best if not the best channel about room acoustics ever. Everything you need to know explained in a very simple but effective way. No need to scroll and search in hundreds of forum posts. This is gold! Keep up. Highly appreciated.
I was going to write this as a comment, but now i dont need to ^^ Im so happy and thankful Jesco Lohan.
He’s for sure been the most helpful..it’s hard to listen to most engineers speak …..just his tone sounds like his logic is undeniable and his theories absolute and u dare not challenge his word
With a 4-inch thick slab of acoustic foam and no air gap, the Porous Absorption Calculator says absorption is down to 80% at around 400hz. If you split the foam into alternating 2-inch slabs in a checkboard pattern, you can get different air gap depths between adjacent slabs. With a 4-inch air gap, 80% absorption drops down to 300hz, but there's an unwanted dip at around 1200hz. With a 6-inch air gap, 80% absorption drops to 200hz with a dip at 900hz, but there's a secondary 100% absorption peak at 1200hz. With a checkerboard array of 2-inch slabs and an upper slab air gap of 4-inches, seems like the 900hz and 1200hz dips would be compensated by the absorption peak of the complementary slab. That would give you an octave lower 80% absorption frequency while cutting the foam thickness in half.
One more note on open-air gapping. I read a GIK mounting test using a 4" rockwool panel where one panel was tested flat on the wall and the other was tested with a 3" open-air gap. The 3" air gap did get a small boost in absorption coefficient starting from 160 Hz and down, but started to create an absorption coefficient loss starting from 630 Hz and up. So no matter what, you don't get something for nothing. It's a tradeoff. Again in this situation though, it's still better to just use a 6" panel over a 4" panel open-air gapped.
Great videos. Most of it actually usable for home listening rooms also. I don't want to build studio but I need to treat my listening room in order to achieve balanced and natural sounding sweet spot.
@Laura Brown stop outside noise doesn't do much to your inside room acoustics itself - absorption and reflection (keep noise out) aren't the same and many stuff like Molton just *reflects* high frequencies, for bass it don't do anything at all
Jesco! this answers my question from your last video. I had built panels last year that were only 4" thick and after taking your courses I learned that they should be 6". Any new panels I built would be 6" but I already invested time and money in the 4" panels, so I ran the absorber calculator and figured out that I could get slightly better response with a 1" gap. It worked perfectly and I noticed a difference. I also used this same approach to calculate the placement of freestanding temporary panels. The only door in my room is in a corner and bass tends to build up there so I placed a 6" broadband absorber during mixing sessions. I used the technique to calculate the optimal placement and air gap to the wall for the temp panel then I placed tape on the floor so I can quickly place it in the same spot. Thanks for the advice !
If you're going to change your 4" panels for 6" panels why didn't you make a 2" gap instead of 1"? 🤔
You have authentic depth of knowledge, and you're quite skilled at conveying complex ideas clearly. This was a real treat to watch, and the best I would ever expect to find for free. Thanks so much for sharing so generously.
Fantastic. Answered a question I've had for years, which I've used my intuition to fix. Excellent.
I’m curious, o guess we’re assuming the gap is against Sheetrock?Would the measurements change if the wall was treated? For example: if I had a room that was treated with 2 inch, then added 6 inch with 6 inch gap in various spots as needed better somehow? Rather than just having a gap with sheet rock.
Very interesting, so if I understand the conclusion at the end correctly, it would be beneficial to have an air gap (all be it not more than the core size), but if you have the space and resources it would still be better to just have a thicker absorption panel that would take up the same space (panel + gap). I did elevate some of my wall panels with acoustic foam on the sides of some tiles (so it has a gap to the wall inside but doesn't have open spaces on the side). But next treatment I will just get foam sheets to just have a thicker panel to elevate them. Thanks a lot! Great channel!
What can I say but, Excellent information and presentation.
Soon after I wonder about an aspect of room treatment I get recommended a video where you cover the topic. It's invaluable what you're doing for us newbies of home studio setups. Thanks a million
Excellent video. Clear and concise backed by scientific principles. You obviously know exactly what you're talking about. I'm an immediate disciple.
Many thanks.
Super informative video, thanks for that. Does this mean that I can have air gaps for my corner bass traps instead of super chunks, and the absorption may be the same or even better?
Some acoustic panels come with a solid backing material such as plywood. In this case I assume that an air gap does nothing, since the wood back acts like a wall. Correct?
most of the low frequencies don't really care about that, they go through - that is why you see bass traps reducing the amplitude of bass frequencies while having a hard outer shell (and sometimes hard inner spacers with air gap). Hope this makes sense. I think for mid frequencies it might be rather true though. Also, real life often overwrites these nice charts, these are just guidelines.
Just discovered your channel….. This simple formula you described is priceless!. I was always told it can be a good idea to leave a small gap behind hung panels, but I never knew there was a specific formula behind getting the best results.
Great stuff !! 😉👍
I am about to do treatment for my first studio. This information is well explained and very timely. Thank you!
Best video on the internet
I have reasons for needing the air gap other than performance - at least two of my planned absorber positions have light switches which I need access to. Using thicker panels is pretty much out of the question.
What I don't see a lot of advice about is how to actually mount panels (in my case GIK) with an air gap. I know GIK have brackets for ceiling clouds, but I don't know if they're the best or easiest option for wall mounting.
Any tips would be appreciated!
Jesco, thank you so much, you've opened my eyes on acoustic
I have a 10cm thick ceiling absorber preventing me from early reflection at listening spot. Does this mean I have to hang this not more than 10cm from the ceiling to avoid the non-effectiveness in the lower mids? Thank you for all this incredible wisdom you share here with us.
one of the best videos in the topic I've ever seen ... now to actually execute the ideas in my "bedroom" studio :)
I am glad I saw this. I have been thinking of making a diffusor by hanging a variety of panels of dry wall of a variety of sizes at a variety of distances from the ceiling. I know there is nothing new under the sun and somebody somewhere must have thought of the same thing. I wondering if a 1 meter by 2 meter panel of drywall say 3 cm from the ceiling might not end up acting as a bit of a bass trap?
Hi, do you sell the plots how to make the absorbers/basstraps, basstraps/diffusers you use? thanks
I heard air gap is important between window and acrylic window insert. Also I'm planning to use 2 exterior doors with space in between for our home studio.
How would that work if the panel is put in a corner? (Meaning the air gap would be triangular). Does the same rules apply in terms of ratio?
Keep up the good content!
Was debating between the whole back wall with all 3” Safe and Sound and pull grill cloth down over or making panels. I guess your recommendation would be to make panels. It’s a heavy bass room.
The absorber should be place as close as possible to the 1/4 wavelength position, where the amplitude is greatest and the absorption most effective. Longer wavelengths have 1/4 wavelengths farther from the wall, so the absorber must be moved farther from the wall to be effective, compared with shorter wavelengths. Please correct me if I am wrong.
So does this mean you want to have varying air gap depths to cover that dip in the midrange? Adding some blocks of absorber on the back in air gap, to get the best of both the airgap *and* the double depth of absorber but without the cost of having a double depth of absorber over the whole panel? Or perhaps alternating airgap and full depth panels (again to reduce the cost of absorber).
Having an air gap at all is a debatable topic. The issue of panel air gaps center around having an "open" air gap vs. a "sealed" air gap between the panel. Some have said that an open air gap may not do much acoustically. Looks like more numerical data is needed in the open vs. sealed debate. The documentation for the Porous Absorber Calculator does not make it clear whether the air gap measurement is based on open or sealed.
Very well explained and clear with the right balance of theory and practical application - I will be checking out your channel - Thank you !
truly incredible work you are doing here!
When you switch that calculator to "random incidence", that effect totally disappears and then it's just deeper = better.
Now I'm wondering if I should back-fill my absorbers for more even absorption.
EDIT: For treating modal frequencies, 0 degrees incidence works since those standing waves hit the wall dead on in a rectangular room. So it's better to use the material to cover more area if making it thicker doesn't increase bass absorption.
Using the largest depth with a single layer over a larger area... But doubling and triple layering the centers or targeting first incidents etc could result in best results...
I have those IKEA square shelves with the open back.. Covered and stuffed and off the wall a few inches. With stuff in them.. Books.. Guitar pedals. Batteries.. A coffee tub.. Surprisingly good compromise.
I bought some higher quality 1” foam (should have bought 2”) but I’m gluing to 3/8” plywood so I can move, reposition or remove them. I was going to space off the wall around 1”, but since the souldwaves will not pass any deeper in the foam before it bounces off the plywood, I won’t get anything from spacing off the wall. Correct? My only thought is some sound waves bouncing behind then bouncing between the wall and plywood backer. Any truth to that? My studio base for guitar with Marshall amplifiers is 12x 8 with 8’ ceiling. My space is small. Carpeted floor.
Very good and logical walk through of acoustics wave speed vs spl.
You articulate very well 👏 fair play, thanks!
I’ve got some GIK Acoustics panels, and they actually have around an inch of gap built in.
Just out of Curiosity, is there any benefit observed if the panel is mounted like a wedge, for example, closest to the speaker has some or no air gap, with furthest away having the opposite property?
This is great, good job Jesco!
i have watched about 20 of your videos since saturday night and feel transformed. i have learned essential things and really appreciate your videos and advice and how well structured all of it is communicated.
so, i am planning to get into building absorbers and bass traps (and maybe diffusors later, if i still got the need and motivation). atm i am calculating the air gap behind the panels, but i have an important questions: do i also need an air gap behind the bass traps? and if so, does the gap have to be all around the bass trap or just in the corner?
i thought about building a standing plate for a bass trap and started wondering, if it would be neccessary to have it be a few centimeters wider all around.
Great explanation! I have a related question... what would be the difference in having an absorption panel close/against the wall as opposed to having them hanging on a stand closer to the listening position, and say 3 feet away from left and right wall?
What about putting the panel with a gap from the wall, but filling the gap with foam, in order to capture those mid frequencies? In other words, wall, foam, panel...?
the gap is to save money and material for a *similar* result, fill it
Great, clear explanation
keep it coming, best treatment advice on the tube !
Hi, i plan to rent a 100 sqm room as a dance studio ( 3.5 meter height ) , i will be using the cement ceiling for ceiling mounts for my hoops/poles . Anyway, the tenant beside me will be a 24 hr CALL CENTER , we still don’t have a partition between us ( on the partition i plan to install the dance mirror ) . For the partition, the owner will install a DOUBLE wall hardiflex . Will that be enough to deaden or block the sound for both rooms? A supplier suggested to : Insert 3 or 4 INCHES ROCKWOOL fiber in between the hardiflex, then on my side - place the MASS LOADED VINYL ROLL on top of the hardiflex acoustic, ( there might be a gap in between this and the actual wall where i will place the mirror , they suggested that instead of using plywood for the mirror to be place, i should use SILICATE BOARD as a replacement, then finally the mirror. Not sure if there is a more cost effective way for this . Thanks your reply will be much appreciated
I’ve just found your channel & this excellent video on this subject. I have a question which is I am about to install side wall panels, & I’m trying to figure out the first/ second reflection points. I’ve heard a lot about using the mirror trick, is this something you would recommend, or would you have a other suggestion?
I am thinking in using now, silk screening mesh fabric to cover my panels. It's made of nylon, stretches very well, and allows the sound to go inside the rockwool 100% letting it do its job completely well, the way rockwool is supposed to work. It is not expensive if bought by the roll at Walmart. Using the correct opening, won't allow the tiny pieces of rockwool get out of the panel, that are really bad if you breath them. What do you think?
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Ok, so now after watching the GIK Acoustics video on Air Gaps, it's pretty clear now that air gapping is really not a good idea unless you are doing extensive frequency testing and you know exactly what you are doing. If you are trying to float a 2" panel an inch or two off of the wall, then it's better to just use a 4" panel flat on the wall. And if you feel like you need to float a 4" panel off of the wall, then it's better to move up to a 6" panel flat on the wall. It appears that... yes, a "sealed" air gap is better than a open air gap, and an open air gap can make your situation worse if you aren't doing serious frequency measuring. Performance-wise it's better to just use a thicker panel flat on the wall over a thinner panel with an open air gap. It also looks like most GIK panels come with an air gap in the back portion of the frame, but it's also sealed with an acoustic cloth cover. Also in smaller rooms, it's almost automatic that you should be using 4" thick panels instead of 2" panels.
Thank you for this channel! you are helping massively
This may be obvious to some, but misleading for others. When you state the depth of the absorption material in your calculations I assume this means the material itself, not the depth of the frame of the panel. For an example some of my panels are 3.25 inches deep, but the absorption material is at the front away from the wall and is only 2 inches deep. That should mean that material is already 1.25 inches away from the wall and close to the optimal equi-distance from the wall as the depth of the absorption. Were panels manufactured with the panel frames twice the depth of the absorbent material there would be no need to hang panels for optimal absorption.
Please correct me if I have misunderstood.
Yes, the material itself.
Great video, thank you. To counteract the dip in mid-range frequency absorption with a large gap, would it be prudent to put an additional layer of absorption on the wall (so effectively double layering the panels, one against the wall, one a few inches off)?
Depends on the room really. Maybe you don’t want less mid and if so then just make the absorption thick and thin but no inbetween or add bass traps and those ugly useless foam because that pretty much only touches high frequencies
Do you have an rt60 freq response of the room?
Very very useful info, and that site is a great tool. Question though, what density is ideal?
Many traps are 10cm deep and placed wall to ceiling or wall to wall which means the depth from the corner angle to the trap is deeper than the trap. Is this wrong? It seems to be common practice
Question for you…I see you have slat diffuser/absorbers, how do you determine the size and positioning of the slats?
Do the cuts and shapes of acoustic foams actually make any difference at all? For eg: compared to a thick block of 2 inch acoustic foam , is a 2 inch pyramid foam better or worse?
Or is it a marketing strategy to make less amount of foam more appealing by saying : more cuts means more surface area means more absorption etc?
it seems the graph with the air gap has more comb filtering going on, though. as much as you may save a few dollars by using an air gap, wouldn't it be better to have a flatter dampening/absorption curve, unless the peaks and valleys are precisely opposite what you're attempting to "fix"?
When you say air gap does that mean the wood frame away from the wall you can stick your hand behind it gap or are you building a larger frame including that space behind the panel as in a 2-inch panel would need a 4" frame or is it just a 2" panel with a 2" spacer leaving a 2" see-through Gap behind the absorber?
Great video thx for sharing.
In this case I could away with flat panel bass traps instead of triangle 🔺️by leaving space. 8 inches panel and leaving 8 inches or more I'll be able to achieve that. Bast explained thx again.
would love to see a graph for thicker panels
Another great video. I'm wondering how things would be affected by storing things in the air gap. I use my space primarily for mixing but also to record drums a lot and sometimes rehearse too, so space management is important and I have a lot of gear to store (multiple drum kits...). So I have a potentially crazy idea of putting floor to ceiling storage on the back wall (50cm deep) with various drums, stands, mics, cables etc and putting a "wall" of moveable gobos essentially in front of that. Would those panels then need to be 50cm deep themselves to have any effect? Would they even do anything to low end if there is stuff of various shapes and sizes behind them?
Does the same go for when hanging panels overhead as a cloud? Distance fro panel or cloud to ceiling?
Great video as always. Question: Is there an upper limit on rockwool thickness when it comes to bass trapping? For example, let's say you have a room big enough where you can pack a full 1m (!) of rockwool against the walls. Is the bass even going to get through that much material or are you just wasting rockwool at that poing?
Thanks as always for the great videos.
great question, man.
I'd simulate it in the absorption sim Jesco showed here. It's vital to enter the Rockwool characteristics in the variables.
Or, you can split it like he suggested, ie. .5m material with .5m gap.
Or just go for it ... put up a full 1m depth.
Typically the thicker the velocity trap, the less dense the material requirements are.
@@FOH3663 Good tip! I should have mentioned that I did this and that's what the simulator reported (after about .5m there is very little difference). The only part I couldn't figure out was the flow resistivity for Rockwool RWA-45. From what I have seen, it's right around 10k (the default value at AcousticModeling.com) but that was extrapolated data from a random acoustics forum, not an official Rockwool spec sheet. I'm not sure they've posted that information for RWA-45. Anyway thanks for your good response!
@@LeoMakes
You're welcome
Gearslutz acoustics forum would be a solid source for greater specificity in the material density etc.
@@LeoMakes You probably got it sorted by now, but it mainly depends on how low your speakers extend and how dense the material you're using is. So it could be worth it if:
a) The insulation you're using has very low flow resistivity (1000-5000)
b) Your speakers are producing sound in the 20-40hz range
If the flow resistivity is high, you won't get much beyond 300-500mm thickness. If your speakers taper off at 50hz, there's no point anyway because the main absorption increase is to frequencies below that.
Good explanation of why this occurs. But one question: would you not want less midrange absorption? Isn't the purpose to reduce LF frequency while preserving mid and high source content? I've read pros and cons to broadband absorbers for this reason. Second, thanks for the comment on distinguishing between velocity v pressure; could you do a short vid elaborating on this dynamic in application of treatment?
The blip he demonstrated with the simulation isn't "preserving mid and high content".
He was simply demonstrating the effects of spacing.
To retain mid freqs and upward, you'd need slats, or Visqueen faced traps... that way the absorption is strongly weighted to the LF.
Hi Jesco, I've seen this on an acoustic website and it's completely thrown me re the gap behind a panel. Can you throw any light on this?
NWAA Labs, Inc
2017 ASA NOLA
Absorption
Myth: Wall mounted panels that are spaced
off of the walls will increase their low frequency
absorption as the space behind increases.
Fact: This is only partially true. The low frequency
absorption only increases when the spacing from the wall
does not exceed 1 inch. The effect disappears after 1 inch.
This only applies to unimpeded airspace.
Good video, great channel. thanks for the advice.
Can you make a 6in panel with 2inch panel and 4in panel tied together in a frame? Or am I better off finding the 6in panel?
I’m thinking about moving blankets.
They are about 1/2 thick
Using 3 layers, one could stacks them 2,4 and 6 inches from the wall
Did I get this right?… The green line representing the sound reduction of a gap less 100mm panel has a far more linear response with slightly wider frequency absorption range in the low end? If so, I feel the cost of the extra 50mm insulation is worth it.
I’ve chosen to go with a 100mm framed panel with 60mm depth of a more semi- rigid mineral wool board with 40mm of a less rigid lower density mineral wool board facing it.
Amazing, really - thank for the session on what to be thinking about before you start hanging your absorption panels..(I was just in the process of doing this) ...and thank you for the valuable set up procedure on how to hear the sweet spot for your speaker placement, I was able to understand the process and it gave me more of an insight on what I should have been focusing on - Thank you Acoustic Insider!
Hi, thanks for your videos, they are great! A shot question I have been pondering on... Is there anything to be gained mounting two thinner panels with a gap between them an then a gap to the wall? Or maybe a the second up against the wall...
Could you increase the density of the foam rather than move it away from the wall? Thanks.
Just a question: how to know how much of absorbtion you need in a specific room? how to know how much you want to kill in the spectrum, and not only where?
Also fellow Mitmensch mit male-pattern baldness wollt ich nur mal sagen: sieht rasiert richtig gut aus ;)
Great channel, subbed and checking all your other videos :)
I have a question though, going to build new panels soon, (200mm depth cotton wool) but i'm never quite sure which density would suit my needs. Any info on that ?
I just came across this video, what an excellent explanation thank you! I have 1 follow up question, so for example assuming a 2" sound absorbing panel and a 2" air gap, would a 2" thick Rockwool inside of a 4" deep frame, mounted flush to the wall, still be the same as a 2" deep panel, mounted 2" off of the wall?
Great video, great channel. Thank you.
Using the Porous Absorber Calculator at the acousticmodelling link in the video, the half-wave dip in absorption you point out is much less of a problem when the calculator's Random Incidence option is checked. Does this imply that using pyramidal or triangular-ridged acoustic absorption foam is a better choice than flat-surfaced foam for deep air gaps?
great videl man! I'm wondering what the difference would be between just placing the panel further from the wall vs kind of making the frame of the panel deeper so that you effectively create a closed air pocket. I've heard that, that's how you should actually do it, but I was never able to test and compare both versions.
what do you think?
Good video and the PDF was an interesting read. My studio is visually a mess but sonically I'm delighted. Gradually I am tidying the room but the question is, how much harm will tidying the room do to the acoustics? I'm seriously considering putting up drapes to simply hide the cluttered shelves! 😀
Curtains will over the shelves will absorb too much high frequencies. Would be better off just moving all the shelves to another room or a storage cupboard.
Great video, thank you! To-the-point, and explained the 1-to-1 ratio of thickness to air gap very clearly.
I am currently about to build acoustic panels with 3.5” thick mineral wool insulation, so I’ll be planning on building stands for those panels so that they sit 3.5” away from the wall. I know it’s not 6 inches thick (which would be most ideal), but I also don’t have a lot of room for 6 inch thick panels in my home theater testing room that I’m building for my own channel. Not the most ideal, but better than no panels at all. 😁🤘 Thanks again! You have a new subscriber!
Hi! Would I be able to use some clips from this video in my own video about building out my own DIY acoustic panels? No audio - just me talking over some short clips from this video, since I want people to know where I got the science behind it. I reference this video a few times, so hopefully it’ll get more views too! Thanks! 😁
How does this work with corners? the air gap will obviously be rectangular in shape... I'm sure it's fine since that is the way most people cover their corners but I'm still curious
Thank you! Great presentation. Question: we are getting repetitive bass sounds...day and night constantly from neighbors...! We have dual pane windows and dampers. Could bass be traveling via our plumbing? We love music...but what can we do on the entire length of one side of the house??? We live on a corner and basically have six neighbors. Echo effect probably plays a role? Any suggestions welcomed. Jim
That’s why I’m here. It’s insane on the neighbors alll day and alll night. They never stop.
quick question:
Is 300mm depth of absorber better or 150mm with 150mm air gap? if I type it into the calculator the curves are nearly the same, only the air gap variant has some dips and the other curve is like a radius.
Thanks for the video. Is it reasonable to substitute "home theatre" for studio with all this info and setup? I'm expecting a home theatre is at best attempting to emulate / reflect the same sort of acoustics they had when creating the audio in the studio when they produced the audio tracks. Cheers, David
Why doesn’t the air gap apply to basstraps or does it?
Like placing a big 6x6 inch basstrap 6 inch from both corner walls?
Does this equally apply to panels with a solid backing and open back?
What if the 2” panel has wood panel on the entire back side? Will the air gap still be effective?
Thanks for your awesome content! Very well explained and easy to digest even not having a lot of upfront knowledge.
Is this (in a more moderate way) also applicable to living rooms where you listens to music and want to treat the room? I‘m thinking about the wall behind the speakers and basically building a big wooden frame with Pamela’s you find in centralized concert rooms and put absorption material behind sand possibly an airspace. In the living room I‘d not make this deepen than 10cm though as it would otherwise interfere to much with the room and it‘s usage as a living room
Thanks Jesco, for another informative video. I really appreciate you sharing this knowledge.
Really interesting video, thanks for the calculator! Would be keen to understand if it is possible to do similar measurements with a flat panel in a corner where the depth is then not just a fixed amount, instead deeper in the middle than the edges.
hi , thanks alot for your help , i checked the site and i have a question , what if we use 2 layers of 4 inch panels each one with 4 inch air gap ? does it work ?
Hi dear friend. Let me ask you a question please upon the vital air gap between the wall and the rock wool. Lets say I use 20cm deep rockwool. If i build a 30cm deep frame and put the rockwool onto the front 20cm depth (with dividers where the rockwool will sit)... that will leave me with 10cm free air gap on behind. Ok? When placed on the wall there will be no visible air gap. But actually inside I will still have the 10cm free air gap depth. Well... is that considered as efficient air gap for the best possible bass absorption, while there will be no air flow from the outside? My question is just for aesthetics. I prefer panels that sit flush to the wall instead of gaps.
Thank you.
It would be good, if a series on home theatre can be made
You have a very optimistic view of how these air gaps work. The models in that absorption calculator assume that the air gap is enclosed, and that all of the sound is therefore funneled into a wall and back through the absorber. But that isn't the case when you're talking about air gaps behind a mounted panel, this gap is not enclosed. So a good amount of the sound (especially from the outer 50% of the panel) will not make it back through the absorber, but instead spill out from around the unenclosed air gap.
If you wanted this to work like it does in the models, you would need to build that air gap into the panels themselves, so that they're enclosed by a rigid material.
I am gonna test it out, but on that "Absorber Calculator" document page is stated : "This calculator estimates the absorption coefficient of a porous aborbent in front of a rigid backing (such as a solid wall) with an optional air gap between the absorbent and the backing. Up to two absorbers can be modelled at once." There is no statement about a need of the airgap to be anyhow enclosed.. go figure
@@odalv7278 Yeah I've tested it myself, there's no question that an airgap does improve performance, it's just not as drastic as the model predicts (for the reason I outlined).
So when he says 'you can leave a 3" gap and effectively get the absorption of a 6" panel', that's not true. You'll get some improvement, but it'll only be about 20-50% as pronounced as the model predicts.
If I make my panels 6inches core, how much fiber glass I need to put in the panel? What thickness of fiber glass should I use? I have 2.5 inches fiber glass. Is that useful?
question. I built a bunch 12" Deep* skyline diffusers. 2 foot x 2 foot. they're big and heavy. 2/3" thick plywood
would the same principle apply to spacing them from the wall as well?
Cool video, thanks, greetings from far Chile.
And what about bass traps? should there be an air gap too?
Can you please let us know, when we use rockwool "sound n safe", what standard gap should we have with it? Please.
So am I to understand that corner base traps will work better if you only put say 3 inch of rigid paneling (I'm thinking roxul rockboard) in front of the corner and leave the corner per se open/empty?