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
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 !
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.
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.
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!
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.
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
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?
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?
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?
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.
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!
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?
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.
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.
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.
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.
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? .
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?
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
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?
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?
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?
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.
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 ?
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!
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.
So does this same principle apply to the actual furniture in the room too example small side board pulled 1 inch from the wall instead of being pushed right up against the wall ?
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.
bro i have a question, i just installed Rockwall AP , i want to know is it safe to breath around them on the studio as i cant breath very well on the room. did you hear about any breathing problem could happen or cancer casing effect on keep rock wall panel around you. thank you
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).
Just a quick question, wouldn't "random incidence" be a better approximation of the performance in a real room when you're calculating, or do you prefer to see the numbers for normal incidence to get a better idea of the material's performance if diffraction within the material and grazing incidence are removed from the equation? Thanks
I was going to comment the same. For rough estimate work, one should vaguely average the two graphs for panels on walls normal (perpendicular) to a primary sound source direction. As an example, both the "front" and "rear" walls in a listening room with speakers on the "front" wall will have more perpendicular character by a bit, but plenty of random incident angle. The side walls will be nearly 100% the random regime. Also, I don't see enough videos explaining that very dense absorbers, like say Corning 703 rigid fiberglass have strong surface reflectivity. This is why in properly engineered solutions like say cubicle walls, you find layers of differing density and sound slowing. Good cubicle walls are upholstery fabric - automotive style jute - rigid fiberglass - cardboard sheet and then reverse the first 3 layers (the cardboard is a reflector to dump remaining sound energy back the way it came to isolate spaces). Differing densities and flow resistivities "traps" sound and diffuses to white noise what comes back out much better than any homogeneous material, and most importantly, largely remove resonant nodes.
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
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!
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.
3 года назад+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 ?
How would you implement the air gap ? I've got several 6'' porous absorbers and would love to raise my absorption coefficient from 0.4 to 0.6 at 100 Hz as thats exactly the problem-frequency-band of my room. I just don't know what's the best way to implement the gap. Would be great if you could do a hands on video how you'd install a gap like that. cheers from austria :)
I cut four 1.5" cubes of rigid foam (the white shiny stuff that's often used to package electronics) and hot glued them to the back of my (DIY, 7" thick) rockwool panels, then re-hung them using picture frame wire. The blocks are glued a few inches in from the corners, so they aren't visible. Now the panels sit securely on their four 'feet', and appear to be floating away from the walls... a nice look that would be even more awesome with some wall-washing LEDs added to the panel backs. The panels are nothing but double-thick rockwool sheets sewn in a fabric casing with either a minimal wooden frame on the back (new ones) or a solid sheet of thin MDF (early ones), so they're rigid enough and weight isn't an issue. I also made a 3.5" thick ceiling cloud using a back frame (with a bit more structure to it, and some buttons to hold things together) and hung it a few inches below the ceiling. I did this more to facilitate installation than for any audio benefit, so it's nice to hear that's added. I see that the software includes the phrase "rigid backing"... I'm assuming this means a solid back like a sheet of thin plywood or MDF board, versus a sparse frame and fabric. Does this backing make a huge difference in performance?
I am making my own panels and can make any size and shape and thickness I want. I have covered all tri corners and bi corners, and near reflections and some rear wall. I still need to control main room modes, about 90 Hz and 120 hz, in my rectangular room. From your video I realize I need thicker bass traps with a gap, behind them. So is it better for me to make some thicker traps and leave some wall exposed to let highs and mids pass a little? Or should I continue and cover all walls completely? Should I put a thin ply layer, maybe 7mm, with holes, on the front of some traps to reflect highs and mids but still trap bass?
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?
This can only be answered with "it depends". For example on the distance, as indicated in the video, between the wood back and the wall. And gaps between panels that allow sound to enter at that point. We know from double glazing (~airtight) that heat insulation peaks at 15mm gap which is that maximum gap at which the air inside remains standing still and above that there will be reduction in efficiency due to airflow (convection). Make the gap wider and it starts to become a frequency dependant sound insulator. I have a 1902 house with a thick single brick outer wall. At that time they would nail wood slats on the inside (about 15mm thick), then nail jute fabric (aka sackcloth) over that, and next stick wallpaper on that. I replaced that with an air barrier, hi-tech insulation foam, and two layers of sheet rock (gypsum board) of different thickness. Depending on the order of the sheet rock, it becomes an insulator or amplifier (at certain frequencies). Keep outside noise out and it will amplify noise from inside out a bit, in my case towards the thick brock wall. And these two layers of sheet rock are smack bang flat against each other. A single layer of sheet rock always amplifies in either direction. Then it depends in which frequency range you want to dampen. The presenter of this video has a highish pitch in his spoken voice, but with a bass layer to it that makes it attractive (not dry). Compare that to a piano's central A that in today's tuning is at 440Hz (for its base frequency - it has many overtones that define its tone as both piano and a specific instrument [1]). Then look at the acoustic insulation graph in the video again. If I had a restaurant with a sound problem where people speak louder and louder as more people are in, then I would probably solve that with a layer of simple DIY acoustic panels against the wall with a second layer with an air gap over that. Such DIY panels would not have a wooden back panel, by the way. With human voices, we don't have to worry about bass frequencies where these panels have little insulation impact, in this example. And now I have great insulation in the 250Hz to 1500 Hz frequency range, I guess, looking at the video's graphs. In the hearing of human voices we need the overtones to have excellent intelligibility and as little reflection of these as possible. If you play back recoded music the story is more nuanced. A recording in an acoustically dead space my only come to life when you play it in a room with reflecting walls. Most electronic music cognitively is a total mess between phase and micro-dynamics, many multi-microphone recordings also are a phase mess. These benefit from acoustically dead walls in playback. Play an old recording from the RCA Living Stereo series and I might prefer the acoustically dead walls - because the recording is done with two microphones from a listener's position. [1] in many electrical engineering situations, "sine waves" are used for reference. These do not happen in music, voices, or earth's nature. If - Fourier analysis - you want to construct a 50 Hz block wave from sine wave components, then you need sine pulse trains where each next sine pulse has another frequency and where the block wave has its vertical you would need an extremely high frequency to begin with. I don't think we actually have amplifiers, let alone loudspeakers that can do this. As our ears are passively filtered for our individual frequency range (primarily a matter of dimensions aka size), within that range we have some 20,000 membranes that listen to a narrow frequency band. The associated part of the brain is much faster than the visual brain. Our hearing does wave shape analysis at a bandwidth (precision) that exceeds 20 kHz by a lot and hence we can hear the difference between mother and father, or recognise the voice of someone we never met before, as family. And hear the difference between a cello and a violin both playing the note we call central A on a piano. With that hearing we have great sensitivity for "noise" and easily distinguish alarming noises from generic background noise. As we use comparison networks in the brain between the ears where both phase (arrival time) and wave shape differences are analysed, we know where sound comes from too. In this light, I would adapt acoustic damping to my context or use case as much as possible.
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
We have 25 ft ceilings and an echo problem and would like to make decorative acoustical panels on one wall. If they are 2 in deep how large should the air gap be for normal conversation
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.
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
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?
Hello, Thanks for all those informative Videos, My Room is small. 13'L X 12'W X 8'H so working with the 38% rules my Listening sweet spot is about 5' from the front wall. I`m looking to install two 6'' D X 24''W X48''H Pad behind my monitor. But it`s getting hard to keep a equal triangle with enough stereo width in that 5' space . So Should I keep my Pad Flush to the wall to keep maximum distance between my monitor and the pad or add some space and get the Monitor closer to the Pad. Thanks
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.
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.
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.
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?
Hi! My celling is 8 foot from the floor, and my main issue in my room right now is at 100 - 200hz . Is it ok to mount a 2" lets say 4" away from the celling? I know there is a compromise but that 100 - 200hz region is so anoying. thanks
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"?
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...
good explanation. Would this be true of super chunk absorbers? Should i fill the entire core with Safe N sound, or maybe just the front, to leave an equal gap of dead air behind them?
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.
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?
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
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
Jesco, I have noticed even with a 10 inches of porous material (in my case Rockwool density 30kg/m3 [9000 Pa.s/m2] ) and a 10 inch air gap provided, I am able to see only .5 or .4 absorption coefficient in the graph for low frequency areas. What I am asking is, will this much SAC will help to tame some serious low end and make things better? Will this SAC improves with larger surface area for the panels, especially for low frequency management?
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
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"? 🤔
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.
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.
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!
Hi, do you sell the plots how to make the absorbers/basstraps, basstraps/diffusers you use? thanks
What can I say but, Excellent information and presentation.
one of the best videos in the topic I've ever seen ... now to actually execute the ideas in my "bedroom" studio :)
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.
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
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?
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?
Best video on the internet
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?
I am about to do treatment for my first studio. This information is well explained and very timely. Thank you!
Does this equally apply to panels with a solid backing and open back?
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.
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!
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?
Jesco, thank you so much, you've opened my eyes on acoustic
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.
Very very useful info, and that site is a great tool. Question though, what density is ideal?
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.
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.
Do you know how if panels would be any good for impact noise coming up the walls?
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.
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?
.
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?
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
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?
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?
Can you please let us know, when we use rockwool "sound n safe", what standard gap should we have with it? Please.
How much thickness should be the rock wool? 50 mm vs 100 mm? 2 vs 4 inches?
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?
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.
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 ?
What if the 2” panel has wood panel on the entire back side? Will the air gap still be effective?
Question for you…I see you have slat diffuser/absorbers, how do you determine the size and positioning of the slats?
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!
Very well explained and clear with the right balance of theory and practical application - I will be checking out your channel - Thank you !
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.
While calculating, flow resistivity varies with the product?
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?
So does this same principle apply to the actual furniture in the room too example small side board pulled 1 inch from the wall instead of being pushed right up against the wall ?
keep it coming, best treatment advice on the tube !
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?
Hi..... thanks for the video ... when making panels with rockwool . how to make sure you don't have any loos fiber in the air for health problems ?
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.
Is this result due to the fact that you are moving the panel closer to the speaker?
bro i have a question, i just installed Rockwall AP , i want to know is it safe to breath around them on the studio as i cant breath very well on the room. did you hear about any breathing problem could happen or cancer casing effect on keep rock wall panel around you. thank you
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).
Just a quick question, wouldn't "random incidence" be a better approximation of the performance in a real room when you're calculating, or do you prefer to see the numbers for normal incidence to get a better idea of the material's performance if diffraction within the material and grazing incidence are removed from the equation? Thanks
I was going to comment the same. For rough estimate work, one should vaguely average the two graphs for panels on walls normal (perpendicular) to a primary sound source direction. As an example, both the "front" and "rear" walls in a listening room with speakers on the "front" wall will have more perpendicular character by a bit, but plenty of random incident angle. The side walls will be nearly 100% the random regime.
Also, I don't see enough videos explaining that very dense absorbers, like say Corning 703 rigid fiberglass have strong surface reflectivity. This is why in properly engineered solutions like say cubicle walls, you find layers of differing density and sound slowing. Good cubicle walls are upholstery fabric - automotive style jute - rigid fiberglass - cardboard sheet and then reverse the first 3 layers (the cardboard is a reflector to dump remaining sound energy back the way it came to isolate spaces). Differing densities and flow resistivities "traps" sound and diffuses to white noise what comes back out much better than any homogeneous material, and most importantly, largely remove resonant nodes.
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.
Hi....my bass sweet spot is above the speakers 2-3 feet in front of the sitting spot (equilateral triangle). How to address this ... please help
truly incredible work you are doing here!
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!
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.
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 ?
How would you implement the air gap ? I've got several 6'' porous absorbers and would love to raise my absorption coefficient from 0.4 to 0.6 at 100 Hz as thats exactly the problem-frequency-band of my room.
I just don't know what's the best way to implement the gap.
Would be great if you could do a hands on video how you'd install a gap like that.
cheers from austria :)
I cut four 1.5" cubes of rigid foam (the white shiny stuff that's often used to package electronics) and hot glued them to the back of my (DIY, 7" thick) rockwool panels, then re-hung them using picture frame wire. The blocks are glued a few inches in from the corners, so they aren't visible. Now the panels sit securely on their four 'feet', and appear to be floating away from the walls... a nice look that would be even more awesome with some wall-washing LEDs added to the panel backs. The panels are nothing but double-thick rockwool sheets sewn in a fabric casing with either a minimal wooden frame on the back (new ones) or a solid sheet of thin MDF (early ones), so they're rigid enough and weight isn't an issue. I also made a 3.5" thick ceiling cloud using a back frame (with a bit more structure to it, and some buttons to hold things together) and hung it a few inches below the ceiling. I did this more to facilitate installation than for any audio benefit, so it's nice to hear that's added.
I see that the software includes the phrase "rigid backing"... I'm assuming this means a solid back like a sheet of thin plywood or MDF board, versus a sparse frame and fabric. Does this backing make a huge difference in performance?
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
You articulate very well 👏 fair play, thanks!
I am making my own panels and can make any size and shape and thickness I want.
I have covered all tri corners and bi corners, and near reflections and some rear wall.
I still need to control main room modes, about 90 Hz and 120 hz, in my rectangular room.
From your video I realize I need thicker bass traps with a gap, behind them.
So is it better for me to make some thicker traps and leave some wall exposed to let highs and mids pass a little?
Or should I continue and cover all walls completely?
Should I put a thin ply layer, maybe 7mm, with holes, on the front of some traps to reflect highs and mids but still trap bass?
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?
What about putting the absorber over a corner? I.e. variable gap?
Will solid back panels (that have a solid wood backing) benefit from an air gap between them and the wall?
This can only be answered with "it depends". For example on the distance, as indicated in the video, between the wood back and the wall. And gaps between panels that allow sound to enter at that point. We know from double glazing (~airtight) that heat insulation peaks at 15mm gap which is that maximum gap at which the air inside remains standing still and above that there will be reduction in efficiency due to airflow (convection). Make the gap wider and it starts to become a frequency dependant sound insulator.
I have a 1902 house with a thick single brick outer wall. At that time they would nail wood slats on the inside (about 15mm thick), then nail jute fabric (aka sackcloth) over that, and next stick wallpaper on that. I replaced that with an air barrier, hi-tech insulation foam, and two layers of sheet rock (gypsum board) of different thickness. Depending on the order of the sheet rock, it becomes an insulator or amplifier (at certain frequencies). Keep outside noise out and it will amplify noise from inside out a bit, in my case towards the thick brock wall. And these two layers of sheet rock are smack bang flat against each other. A single layer of sheet rock always amplifies in either direction.
Then it depends in which frequency range you want to dampen. The presenter of this video has a highish pitch in his spoken voice, but with a bass layer to it that makes it attractive (not dry). Compare that to a piano's central A that in today's tuning is at 440Hz (for its base frequency - it has many overtones that define its tone as both piano and a specific instrument [1]).
Then look at the acoustic insulation graph in the video again. If I had a restaurant with a sound problem where people speak louder and louder as more people are in, then I would probably solve that with a layer of simple DIY acoustic panels against the wall with a second layer with an air gap over that. Such DIY panels would not have a wooden back panel, by the way. With human voices, we don't have to worry about bass frequencies where these panels have little insulation impact, in this example.
And now I have great insulation in the 250Hz to 1500 Hz frequency range, I guess, looking at the video's graphs. In the hearing of human voices we need the overtones to have excellent intelligibility and as little reflection of these as possible. If you play back recoded music the story is more nuanced. A recording in an acoustically dead space my only come to life when you play it in a room with reflecting walls. Most electronic music cognitively is a total mess between phase and micro-dynamics, many multi-microphone recordings also are a phase mess. These benefit from acoustically dead walls in playback. Play an old recording from the RCA Living Stereo series and I might prefer the acoustically dead walls - because the recording is done with two microphones from a listener's position.
[1] in many electrical engineering situations, "sine waves" are used for reference. These do not happen in music, voices, or earth's nature. If - Fourier analysis - you want to construct a 50 Hz block wave from sine wave components, then you need sine pulse trains where each next sine pulse has another frequency and where the block wave has its vertical you would need an extremely high frequency to begin with. I don't think we actually have amplifiers, let alone loudspeakers that can do this. As our ears are passively filtered for our individual frequency range (primarily a matter of dimensions aka size), within that range we have some 20,000 membranes that listen to a narrow frequency band. The associated part of the brain is much faster than the visual brain. Our hearing does wave shape analysis at a bandwidth (precision) that exceeds 20 kHz by a lot and hence we can hear the difference between mother and father, or recognise the voice of someone we never met before, as family. And hear the difference between a cello and a violin both playing the note we call central A on a piano. With that hearing we have great sensitivity for "noise" and easily distinguish alarming noises from generic background noise. As we use comparison networks in the brain between the ears where both phase (arrival time) and wave shape differences are analysed, we know where sound comes from too. In this light, I would adapt acoustic damping to my context or use case as much as possible.
Also fellow Mitmensch mit male-pattern baldness wollt ich nur mal sagen: sieht rasiert richtig gut aus ;)
Very good and logical walk through of acoustics wave speed vs spl.
And what about bass traps? should there be an air gap too?
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
We have 25 ft ceilings and an echo problem and would like to make decorative acoustical panels on one wall. If they are 2 in deep how large should the air gap be for normal conversation
I’ve got some GIK Acoustics panels, and they actually have around an inch of gap built in.
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.
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?
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?
Hello, Thanks for all those informative Videos, My Room is small. 13'L X 12'W X 8'H so working with the 38% rules my Listening sweet spot is about 5' from the front wall. I`m looking to install two 6'' D X 24''W X48''H Pad behind my monitor. But it`s getting hard to keep a equal triangle with enough stereo width in that 5' space . So Should I keep my Pad Flush to the wall to keep maximum distance between my monitor and the pad or add some space and get the Monitor closer to the Pad. Thanks
Thank you for this channel! you are helping massively
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.
This is great, good job Jesco!
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.
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.
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?
Thanks for this!
What about corner bass traps. Floor to ceiling or is a 4 footer somewhere in the middle ok?
Floor to ceiling
Great, clear explanation
Good video, great channel. thanks for the advice.
Hi! My celling is 8 foot from the floor, and my main issue in my room right now is at 100 - 200hz . Is it ok to mount a 2" lets say 4" away from the celling? I know there is a compromise but that 100 - 200hz region is so anoying. thanks
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"?
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...
good explanation. Would this be true of super chunk absorbers? Should i fill the entire core with Safe N sound, or maybe just the front, to leave an equal gap of dead air behind them?
how do you mount them in such a way to get such a large gap?
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.
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?
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
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
Jesco, I have noticed even with a 10 inches of porous material (in my case Rockwool density 30kg/m3 [9000 Pa.s/m2] ) and a 10 inch air gap provided, I am able to see only .5 or .4 absorption coefficient in the graph for low frequency areas. What I am asking is, will this much SAC will help to tame some serious low end and make things better? Will this SAC improves with larger surface area for the panels, especially for low frequency management?
Would it make sense to attach 6 inch pieces of wood off the four corners of the sound panel? Otherwise feels like they need to be free standing.