A word of advice on room treatments

[Pandaman617]

So I enjoy doing a decent amount of buying and selling gear both locally and on eBay. Throughout the process I meet many people who are in essence buying their first multichannel setup from me and I always offer to set it up, use REW to place their subs optimally if the room/wife allows, run Audyssey, Dirac or whatever room correction system they have for them and if they buy let’s say a 5.1 setup I paid $200 for originally for $450 or $500 I’ll always throw in KnuKonceptz Sub cables, speaker wire with banana plugs and if needed a mic stand for their room correction. Over the last 3 years I would say I’ve setup and calibrated about 15 newbie systems and I genuinely enjoy it. What I have found is very common are that these guys will read a dated article about applying absorption to the 1st reflection points using the mirror method or will randomly place 1” or 2” cheap Amazon 12”x12” panels everywhere and they’ll tell me it didn’t do anything. I’ve never been into one of these rooms yet where any sort of diffusion is applied. I make it very clear that I am very much a novice in regards to room acoustics. I read quite a bit about the topic and my copy of the 3rd edition of Sound Reproduction is always close by but by no means would I ever claim to be be anything more than an amateur. One room that really stood out to me was a guy told me his friend who’s a home theater “expert” sold him a ton of Monster Cable and subwoofer cables so he didn’t need my free ones and said he got a really good deal at $200 for 7 lengths of cable and two 15’ subwoofer cables. This “expert” also suggested he place 4” thick absorbers that he also was paid to build literally every 4-6” on the side and front walls. This room sounded HORRIBLE. After we removed ALL of the absorbers we re ran Audyssey and REW and I was able to show him the results in REW with Audyssey off/on limited to 350hz both with and without the panels. I directed him to Audioholics as well as the Reproduction of Sound book and he really seemed to be in awe that his “expert” wasn’t able to achieve what I was. My point is that in this hobby just because it’s on a YouTube Channel or forum and endorsed by even dozens of members doesn’t make it correct.

 

[sterling shoote]

So I enjoy doing a decent amount of buying and selling gear both locally and on eBay. Throughout the process I meet many people who are in essence buying their first multichannel setup from me and I always offer to set it up, use REW to place their subs optimally if the room/wife allows, run Audyssey, Dirac or whatever room correction system they have for them and if they buy let’s say a 5.1 setup I paid $200 for originally for $450 or $500 I’ll always throw in KnuKonceptz Sub cables, speaker wire with banana plugs and if needed a mic stand for their room correction. Over the last 3 years I would say I’ve setup and calibrated about 15 newbie systems and I genuinely enjoy it. What I have found is very common are that these guys will read a dated article about applying absorption to the 1st reflection points using the mirror method or will randomly place 1” or 2” cheap Amazon 12”x12” panels everywhere and they’ll tell me it didn’t do anything. I’ve never been into one of these rooms yet where any sort of diffusion is applied. I make it very clear that I am very much a novice in regards to room acoustics. I read quite a bit about the topic and my copy of the 3rd edition of Sound Reproduction is always close by but by no means would I ever claim to be be anything more than an amateur. One room that really stood out to me was a guy told me his friend who’s a home theater “expert” sold him a ton of Monster Cable and subwoofer cables so he didn’t need my free ones and said he got a really good deal at $200 for 7 lengths of cable and two 15’ subwoofer cables. This “expert” also suggested he place 4” thick absorbers that he also was paid to build literally every 4-6” on the side and front walls. This room sounded HORRIBLE. After we removed ALL of the absorbers we re ran Audyssey and REW and I was able to show him the results in REW with Audyssey off/on limited to 350hz both with and without the panels. I directed him to Audioholics as well as the Reproduction of Sound book and he really seemed to be in awe that his “expert” wasn’t able to achieve what I was. My point is that in this hobby just because it’s on a YouTube Channel or forum and endorsed by even dozens of members doesn’t make it correct.

You hit a nerve. I am not an expert at anything but Long Range Marksmanship. I have seen YouTube videos on aspects of that subject produced by folks who just do not know that they do not know and I've seen videos on the topic from folks who know more than me, like shooters from the US Army Marksmanship Unit. From this store of real and counterfeit instruction I think buyers should consider the credentials from all of those professing on the topic; but, I'm sure that is rare, judging from comments like "great video, I learned so much" when the reality was the video delivered nothing to aid that shooter's marksmanship. At any rate, I do not see any solution, it is what it is, a mix of good ideas and bad ideas, which the consumer must sort out.

 

[Pogre]

I always tell folks to do the homework and even consult an actual acoustician before slapping up panels and bass traps all over the place. There's a lot of science behind it, and far more ways to mess things up than help. Trying to treat a room without measurements and the proper knowledge is never a good idea.

 

[highfigh]

I have taken college level acoustics and done a lot of independent study/work with this- the first thing I ALWAYS write or say is:

MEASURE BEFORE TREATING.

Before a problem can be solved, it must be identified and without measurement, it CAN'T be defined.

More often than not, people will recommend bass traps without knowing the room, its response or its problems. That's irresponsible and ignorant.

 

[3db]

I never use Utube for references when it comes to audio. Too many clueless experts out there and its immediately apparent to me when my spidey sense goes off and says this dude is wrong. I did use Utube to replace gas lines and adjust my throtte settings on a gas powered weed wacker but there were step by steps showing the progress.

 

[highfigh]

I never use Utube for references when it comes to audio. Too many clueless experts out there and its immediately apparent to me when my spidey sense goes off and says this dude is wrong. I did use Utube to replace gas lines and adjust my throtte settings on a gas powered weed wacker but there were step by steps showing the progress.

I try to avoid the ones who sound like some gomer who just figured out that computers can access the internet. I generally watch them until I hear a load of crap, then I go to another video. My professor would be rolling his eyes and gagging if he heard this stuff.

 

[TLS Guy]

I do not use room treatments per se.

The most important issue to understand about room treatments, that aces everything else, is optimizing the ratios of the room dimensions.

I realize that this is not possible unless you are building a room from scratch. However, people that do, so often ignore this vital step in the design of their room.

If the room L-W-H ratios are bad, no amount of tinkering will help.

I do use hidden treatments however. The room should be structurally sound and as vibration free as possible. I do put sound absorbing material in the wall. floor and ceiling cavities. That is it for me.

Now a big issue that makes people tinker, is speakers that have a poor off axis response, that does not mirror the the axis response well.

When that happens people go to fruitless trouble and expense to limit reflected sound. However, reflected sound is actually an enhancement to realistic reproduction, and you should not take slavish steps to reduce it.

In may view that really is all there is to know about how to create a good sounding room.

 

[shadyJ]

There is so much financial incentive for bad advice that I regard acoustic treatments as nearly a lost cause. I wouldn't trust anyone but a certified acoustician at this point. The psuedo science in acoustics is pretty bad in the pro-audio realm as well. Room acoustics is not my expertise, but I know enough to recognize an awful lot of bad advice on youtube and various audio sites.

 

[Pandaman617]

You know it’s funny I posted this same comment on another forum and was immediately attacked by guys trying to tell me that some treatments are better than no treatments and a bunch of the comments tagged some amateur building and selling panels out of his garage. This just solidifies this specific site as a solid source of knowledge not sales pitches. There’s so many threads I’ve read from a newbie that say “My speakers don’t sound good or my bass is horrible” the responses are always based in actions from quantifiable data like “Use REW, take measurements and find the best location” or “Re-run Audyssey/Dirac and make sure you do X,Y and Z” as opposed to “You should buy these speakers I just happen to be a dealer of” any advice I give anyone is always followed by “Check out Audioholics too, there’s guys exponentially smarter than me on there and they’ll help you get sorted”

 

[Jerkface]

I mean, in a square room with flat ceilings, you're going to have nulls, and the smaller the room, the more, bigger, and broader-spectrum those nulls are going to be.

Doesn't mean it's not a smart idea to mic it up and get some spectrum analysis before you start throwing panels on the wall and building towers of pink fluff in the corners. OP, your method of just compensating EQ can work a lot of the time, but it's not a cure-all, because sometimes trying to boost frequencies that are being phase-cancelled by reflections just end up boosting nearby frequencies and making the whole situation worse.

But it's still a great way to attempt to fix someone's situation before they have to drag in an acoustician.

That poop about panels every 5 inches?! That's nuts. Even the high-end acoustics people I've consulted only talk of 10-20% wall coverage, even if your goal is to literally deaden the room (as I'll be doing with my garage fairly soon, to use as a rehearsal space).

 

[panteragstk]

I always tell folks to do the homework and even consult an actual acoustician before slapping up panels and bass traps all over the place. There's a lot of science behind it, and far more ways to mess things up than help. Trying to treat a room without measurements and the proper knowledge is never a good idea.

Well there goes my weekend project...

 

[panteragstk]

I never use Utube for references when it comes to audio. Too many clueless experts out there and its immediately apparent to me when my spidey sense goes off and says this dude is wrong. I did use Utube to replace gas lines and adjust my throtte settings on a gas powered weed wacker but there were step by steps showing the progress.

**Cough** there's an audioholics youtube channel**cough**

 

[panteragstk]

In all seriousness I've considered doing some treatments to my rooms, but I'd only be able to do so much just from a space aspect alone in my office.

The theater could use some, and when I finally finish it this year (yay) I'll concentrate on treatments.

I'm going to build one of these for the back wall and haven't really gone further than that.

Auralex makes some good stuff, and in particular I'm looking at their rubber isolation mat for deadening my floors. That with rockwool should help keep the sound in the theater.

I'd love to do it, but don't know if I'd be able to, or what it would entail, but I'm pretty sure I've got the space to extend my room from it's sqaure-ish shape to a rectangle that would make a MUCH better room for my use.

I'd never invest in treatments unless I had a VERY good idea of what I needed to do. You guys will be my acousticians. No pressure.

 

[stalag2005]

What a lot of people don't get, and I having built radio stations did see are issues with open microphones. Sound suppression for that requires a room with almost no reverb because the audio can become muddy if there is reverb in the room. This is very different than the requirements for audio being played. Our ears are tuned to expect reverb and when it is not there the audio sounds aweful. If a room has significant echo, you need to apply a little sound absorption to attenuate but you definitely don't want to suppress. The problem is that most people go all the way to sound suppression which makes the audio sound "dead". A "dead" room actually sounds bad. Proper reflection and placement of speakers can impact the audio and many decent systems are dismissed due to improper sound treatment.

 

[Pogre]

What a lot of people don't get, and I having built radio stations did see are issues with open microphones. Sound suppression for that requires a room with almost no reverb because the audio can become muddy if there is reverb in the room. This is very different than the requirements for audio being played. Our ears are tuned to expect reverb and when it is not there the audio sounds aweful. If a room has significant echo, you need to apply a little sound absorption to attenuate but you definitely don't want to suppress. The problem is that most people go all the way to sound suppression which makes the audio sound "dead". A "dead" room actually sounds bad. Proper reflection and placement of speakers can impact the audio and many decent systems are dismissed due to improper sound treatment.

I've seen quite a few accounts of people turning their rooms into an anechoic chamber by overdoing it.

 

[highfigh]

I do not use room treatments per se.

The most important issue to understand about room treatments, that aces everything else, is optimizing the ratios of the room dimensions.

I realize that this is not possible unless you are building a room from scratch. However, people that do, so often ignore this vital step in the design of their room.

If the room L-W-H ratios are bad, no amount of tinkering will help.

I do use hidden treatments however. The room should be structurally sound and as vibration free as possible. I do put sound absorbing material in the wall. floor and ceiling cavities. That is it for me.

Now a big issue that makes people tinker, is speakers that have a poor off axis response, that does not mirror the the axis response well.

When that happens people go to fruitless trouble and expense to limit reflected sound. However, reflected sound is actually an enhancement to realistic reproduction, and you should not take slavish steps to reduce it.

In may view that really is all there is to know about how to create a good sounding room.

I would add- many people use equipment that's not made for small rooms, in small rooms. That's a terrible plan and leads to problems that can't possibly be 'treated away'. Narrow dispersion patterns at >moderate SPL can be one of the worst problems but also, wide dispersion speakers that are not exactly 'near' or 'adjacent to' side walls cause longer delays WRT first reflections than can be allowable- this is the problem with my room, but I didn't build the house, I bought it and made some interior changes that created a larger space by removing most of one side wall, so that caused an imbalance in reflected vs direct sound. The use of REW made it possible to correct that and unless the SPL is very high (which is almost never), there's no problem.

Still, most of the walls and the ceiling are reflective, but obstacles prevent a lot of problems. The floor is carpeted, so there's no reflection coming from that.

The fundamentals and principles are fairly basic, but determining the degree of treatment is where this becomes complex because the effectiveness of various materials vary so much. In addition, I think people believe that low frequency treatment is easy, but it's the most difficult if they're trying to achieve a flat response- they should work toward a smooth response, instead.

 

[highfigh]

In all seriousness I've considered doing some treatments to my rooms, but I'd only be able to do so much just from a space aspect alone in my office.

The theater could use some, and when I finally finish it this year (yay) I'll concentrate on treatments.

I'm going to build one of these for the back wall and haven't really gone further than that.

Auralex makes some good stuff, and in particular I'm looking at their rubber isolation mat for deadening my floors. That with rockwool should help keep the sound in the theater.

I'd love to do it, but don't know if I'd be able to, or what it would entail, but I'm pretty sure I've got the space to extend my room from it's sqaure-ish shape to a rectangle that would make a MUCH better room for my use.

I'd never invest in treatments unless I had a VERY good idea of what I needed to do. You guys will be my acousticians. No pressure.

Make sure the walls of the theater are insulated- I have posted several times about a theater I worked on that had a serious dropoff in the low end and it was because the insulation crew failed to do their job on that side. Unfortunately for them, they worked for the homeowner, who also happens to own a large insulation company. DOH!

Before that wall was insulated, it rang like a drum but once it was filled, it was dead in that region and the problem was solved.

Also, if you can make the walls non-parallel and/or add bump outs at the back, a smallish soffit around the perimeter of the ceiling and columns that complement the soffit at the front & back, it helps, a lot. I'll see if I can find the photos of the theater with the uninsulated wall- the bottom of the soffit was level, but the inner face was angled about 15° with similarly-shaped columns at the front for the main speakers & subs and larger soffits at the front and back- across the front for the large center channel speaker system and across the back to house the projector. This theater also had a platform for the rear seats, which was two steps above the floor.

 

[panteragstk]

Make sure the walls of the theater are insulated- I have posted several times about a theater I worked on that had a serious dropoff in the low end and it was because the insulation crew failed to do their job on that side. Unfortunately for them, they worked for the homeowner, who also happens to own a large insulation company. DOH!

Before that wall was insulated, it rang like a drum but once it was filled, it was dead in that region and the problem was solved.

Also, if you can make the walls non-parallel and/or add bump outs at the back, a smallish soffit around the perimeter of the ceiling and columns that complement the soffit at the front & back, it helps, a lot. I'll see if I can find the photos of the theater with the uninsulated wall- the bottom of the soffit was level, but the inner face was angled about 15° with similarly-shaped columns at the front for the main speakers & subs and larger soffits at the front and back- across the front for the large center channel speaker system and across the back to house the projector. This theater also had a platform for the rear seats, which was two steps above the floor.

Luckily I thought of that before we built the house. I wish I would have done some things differently, but this builder was very much a "stick to the plans" guy and it was annoying.

My walls all have blown in insulation that does a great job compared to the pink stuff, but I really wanted rockwool around the entire room. Hell, every room honestly. If I re-sheetrock and extend the room I'll do rock-wool everywhere and do a better job with speaker placement. Speaker placement now isn't bad, but it's not ideal.

If I can't extend the room I probably won't re-sheetrock it. Speakers all sound great except for the lack of bass from the front. I plan to work on that when I'm doing everything else. I'll update my thread.

I'd really liked to have had quiet-rock sheetrock. Supposedly very little cost difference, but blocks sound from going room to room significantly. Add rockwool to that and nothing's getting out. At least, that's what I hear.

 

[highfigh]

Luckily I thought of that before we built the house. I wish I would have done some things differently, but this builder was very much a "stick to the plans" guy and it was annoying.

My walls all have blown in insulation that does a great job compared to the pink stuff, but I really wanted rockwool around the entire room. Hell, every room honestly. If I re-sheetrock and extend the room I'll do rock-wool everywhere and do a better job with speaker placement. Speaker placement now isn't bad, but it's not ideal.

If I can't extend the room I probably won't re-sheetrock it. Speakers all sound great except for the lack of bass from the front. I plan to work on that when I'm doing everything else. I'll update my thread.

I'd really liked to have had quiet-rock sheetrock. Supposedly very little cost difference, but blocks sound from going room to room significantly. Add rockwool to that and nothing's getting out. At least, that's what I hear.

The largest difference in isolation comes from decoupling the theater from the framing for the upper levels- the mechanical connection allows energy to transfer at a much higher speed and no absorptive materials will affect it unless they're between the theater and the framing, which prevents a mechanical connection (nail, screw or bolt). If any mechanical fastener is used, part of the isolation has been negated and if the fastener forces the framing members together, the energy transfer is far stronger. 'A box in a box' refers to this concept.

However, WRT pink vs blown in vs rock wool- pink works great; don't let anyone tell you that it doesn't. A denser material works better, but it still does a lot to prevent resonances and sound escaping to other areas, especially if it's thick enough to cause the drywall to press against it when it has been screwed in place. That prevents the drywall ringing like a drum head and that was THE cause of our problems in that theater. Once insulated, hitting it with my hand only made a thump, no resonance at all. Using batts or rolls that are thicker than the stud dimensions actually compresses the fiberglass and effectively increases the density, therefore, makes transmission more difficult.

Unless the walls have a vacuum, there's no way to prevent ALL sound escaping because there's always some kind of mechanical bond between the air in the space where the sound originates, the inner layer, framing, outer later and the air outside of the space. The main techniques used to limit this are:

-Green Glue
-Acoustically designed wall coverings (Quiet Board, an inner layer of something like particle board/MDF, fiberboard sheathing
- Mass loading (Dynamat or other rubber membrane)
- Resilient channels to allow the wall panels to resonate in sympathy to the energy, thereby decreasing the transfer
- Rubber pads under the wall framing, when the theater is mounted on an upper floor and sound penetration to lower levels must be handled. This is much more difficult to control because total isolation from lower levels is almost impossible.

Anything that adds mass to the wall will help to block sound but it usually doesn't do anything to absorb reflections.