What if you put R-38 batts EVERYWHERE?

[marspe]

Hi All,

Just wondering about this... It seems that the main benefit of Rigid vs. Fluffy is space. What if space isn't an issue? If you could give up 12" of space on every wall in your room (Front, Back, and both Sides) would stapling fluffy 12" x 24" x '4 R-38 batts EVERYWHERE (every wall floor to ceiling) be just as good as building traps and panels? I suppose you could build a false 'fabric' wall in front of the R-38 to keep it contained. Maybe you could mount it with the paper side of the batts facing the room on the back wall and non-first reflection points to keep it from being to dead?

The only reason I'm speculating about this is that R-38 batts are CHEAP. You could do a pretty good sized room like this for under $500. The bass trapping would probably be awesome, I'm just not sure if it would be to 'dead'.

Anyway, just thinking out loud here, any opinions are appreciated.

[SAC]

Put very simply, you would succeed in constructing a very dead, uncomfortable room.

Treating a room is not simply devising novel ways of filling it with absorption. However, I can understand how you might have reached that conclusion...

It is about mitigating certain acoustical anomalies (such as modes) and dealing with the arrival times and amplitudes of specular reflections in such a manner as to optimize the intelligibility and imaging of a source.

And while most focus on simply dealing with the gross issues such as room modes and attempting to damp early reflections, there is MUCH more to a comprehensive acoustical room model that addresses both physics and psycho-acoustics.

Quite frankly, while it is a convenient intro for some to simply understand that absorption can be used in a controlled manner to address some of the issues, it is erroneous to suggest that by 'going crazy with absorption' and attempting to eliminate all reflections is a prudent or productive. You are simply 'moving problems around'. There is 'a bit' more to the science of acoustics then simply filling a room with absorption - regardless of its density...or color...cost...or whether it is Fiberglass or some mystical alternative material.

[Glenn Kuras]

Originally Posted by marspe

Hi All,

Just wondering about this... It seems that the main benefit of Rigid vs. Fluffy is space. What if space isn't an issue? If you could give up 12" of space on every wall in your room (Front, Back, and both Sides) would stapling fluffy 12" x 24" x '4 R-38 batts EVERYWHERE (every wall floor to ceiling) be just as good as building traps and panels? I suppose you could build a false 'fabric' wall in front of the R-38 to keep it contained. Maybe you could mount it with the paper side of the batts facing the room on the back wall and non-first reflection points to keep it from being to dead?

The only reason I'm speculating about this is that R-38 batts are CHEAP. You could do a pretty good sized room like this for under $500. The bass trapping would probably be awesome, I'm just not sure if it would be to 'dead'.

Anyway, just thinking out loud here, any opinions are appreciated.

You don't need to put it "Everywhere", but if you make fluffy fiberglass 12" thick it would preform well. I have seen guys buy the rolls of fiberglass and stack them floor to ceiling in corners which will work.

[marspe]

Originally Posted by Glenn Kuras

You don't need to put it "Everywhere", but if you make fluffy fiberglass 12" thick it would preform well. I have seen guys buy the rolls of fiberglass and stack them floor to ceiling in corners which will work.

Thanks for the reply... What about Front Wall & Back Wall? Most of what I've seen recommended is to bass trap the corners (Tri-Trap) and center (Monster Bass Trap) of the Front and Back walls. Is trapping the rest of the front & back wall that bad an idea?

[My Tiny Circus]

...and ended up as SAC predicts, with a very dead and uncomfortable room. Now I have rigid panels on hooks so I can add or remove them quickly to tweak the dampening. I shall take some pictures.

Originally Posted by marspe

Hi All,

Just wondering about this... It seems that the main benefit of Rigid vs. Fluffy is space. What if space isn't an issue? If you could give up 12" of space on every wall in your room (Front, Back, and both Sides) would stapling fluffy 12" x 24" x '4 R-38 batts EVERYWHERE (every wall floor to ceiling) be just as good as building traps and panels? I suppose you could build a false 'fabric' wall in front of the R-38 to keep it contained. Maybe you could mount it with the paper side of the batts facing the room on the back wall and non-first reflection points to keep it from being to dead?

The only reason I'm speculating about this is that R-38 batts are CHEAP. You could do a pretty good sized room like this for under $500. The bass trapping would probably be awesome, I'm just not sure if it would be to 'dead'.

Anyway, just thinking out loud here, any opinions are appreciated.

[Glenn Kuras]

Originally Posted by marspe

Thanks for the reply... What about Front Wall & Back Wall? Most of what I've seen recommended is to bass trap the corners (Tri-Trap) and center (Monster Bass Trap) of the Front and Back walls. Is trapping the rest of the front & back wall that bad an idea?

No trapping the back wall is never a bad thing as you can have nulls and peaks coming from that area. Treating the front wall is recommend to help SBIR if it is a problem. Learn what is SBIR (Speaker Boundary Interface Response).
BTW if you are worried about absorbing to much of the high end you can always face the non early reflection areas with something like FRK. Cardboard could work or better yet you can use a bent piece of wood to form a poly diffusor.

[marspe]

Originally Posted by Glenn Kuras

No trapping the back wall is never a bad thing as you can have nulls and peaks coming from that area. Treating the front wall is recommend to help SBIR if it is a problem. Learn what is SBIR (Speaker Boundary Interface Response).
BTW if you are worried about absorbing to much of the high end you can always face the non early reflection areas with something like FRK. Cardboard could work or better yet you can use a bent piece of wood to form a poly diffusor.

Glenn,

Thanks again for the response... So trapping front & back walls is a good thing. If I used R-38 with the paper backing, is that equivalent to FRK? If so I could mount the batts on the rear wall with the paper facing into the room.

Thanks for info!

[Seamus TM]

I would leave the back wall paperless and have the Kraft paper facing out into the room on the front wall.

There really isn't much high frequency information bouncing off of your front wall from your speakers.

It's either
A) not coming directly from the speaker due to the directivity of the high frequencies coming from the speakers, or
B) bouncing around the room, off the front wall and to you, which would probably be well past the 20ms gap (or so low in level), if that's what you are trying to achieve.

What it DOES do is make things like talking or plucking around on an acoustic guitar more natural sounding.
In other words, it doesn't hurt the acoustics of your room as far as your speakers are concerned, but it makes the room less of a vacuum coffin to just hang out in.

Just my $0.02

[DanDan]

+1 to Seamus post.
It may not be necessary or desireable to treat the front wall. Glenn did say IF you have an SBIR issue. If you do, it could be from the side wall just as easily as the front. Ethan has an article about front wall treatment on his site.
If left untreated or with a HF reflective membrane, there is a possibility of flutter if similar area of the back wall is also reflective.
DD

[marspe]

Originally Posted by Mumblesound

I would leave the back wall paperless and have the Kraft paper facing out into the room on the front wall.

There really isn't much high frequency information bouncing off of your front wall from your speakers.

It's either
A) not coming directly from the speaker due to the directivity of the high frequencies coming from the speakers, or
B) bouncing around the room, off the front wall and to you, which would probably be well past the 20ms gap (or so low in level), if that's what you are trying to achieve.

What it DOES do is make things like talking or plucking around on an acoustic guitar more natural sounding.
In other words, it doesn't hurt the acoustics of your room as far as your speakers are concerned, but it makes the room less of a vacuum coffin to just hang out in.

Just my $0.02

What if its a 5.1 setup with surrounds on the side and rear walls? Glenn you chime in too. :-)

[SAC]

Just a thought and a comment regarding a characteristic that is all too characteristic of so many threads...no need for anyone to become upset...


...You know what would really be nice?

That would be if folks took a few minutes to become familiar with, and to specify, the acoustical room model that they wished to achieve BEFORE asking or proposing solutions.

I find it 'interesting' that SO MANY discussions begin with proposals or questions regarding specific solutions and THEN (sometimes) gradually devolve into an a mention of a desired acoustical room response. And even more times, that is NEVER identified!

Talk about selecting a route before the desired destination is known....

[avare]

Originally Posted by SAC

That would be if folks took a few minutes to become familiar with, and to specify, the acoustical room model that they wished to achieve BEFORE asking or proposing solutions.

+1.

Andre

[Seamus TM]

Very true, and I apologize for making it worse by blindly proposing random treatment.

To the OP:
What do you want to do in this room?
5.1?
Free standing speakers?
Oh, and going by your original post... what did you intend to do about the ceiling and the floor?

Originally Posted by SAC

Just a thought and a comment regarding a characteristic that is all too characteristic of so many threads...no need for anyone to become upset...


...You know what would really be nice?

That would be if folks took a few minutes to become familiar with, and to specify, the acoustical room model that they wished to achieve BEFORE asking or proposing solutions.

I find it 'interesting' that SO MANY discussions begin with proposals or questions regarding specific solutions and THEN (sometimes) gradually devolve into an a mention of a desired acoustical room response. And even more times, that is NEVER identified!

Talk about selecting a route before the desired destination is known....

[DanDan]

I understand the frustrations. With no disrespect or the even worse converse 'too much respect' GS is very welcoming to newbies. Studiotips might be a better place for higher brow ventures, but is probably not so welcoming.
In that context I think it is quite OK to simply assume a small ( soon to be quite dead) listening/mixing room. Most will simply want it to sound as best it can. In such circumstances I believe the common broad advice (Bass Traps in Corners, Cloud and so on) is completely valid. I believe there is a need for encouragement to get people to actually do this. Many look and read, get put off by seeing uncertainties, then don't do it.
This is a pity as the results from even rudimentary treatment totally trumps any other form of spend.

DD

[marspe]

Hi All,

I probably should have prefaced this with the fact that the room isn't built yet and its dimensions are subject to change. The only dimension that is set in stone is the Width which is 15'. The Length could be 20'-25' and the height could be 9'-12'.

Yes it will be for 5.1 surround and there will be surround speakers on both the back and side walls. The speakers will be on stands, or mounted directly on the wall (rear, maybe side surrounds). There is a 'client credenza' that will be behind the side surrounds so rear surrounds will be necessary for the clients.

I guess the reason I originally brought up putting R-38 everywhere is that every DVD/Editorial room I've ever worked in (Sony Pictures, Universal Blue Wave, Fox) has acoustic treatment EVERYWHERE. Since there is fabric covering it I can't be 100% positive, but if you push against the fabric it feels like 703 or 705 (rigid fiberglass). Of course I don't know how thick it is, but it is on every wall (Front, Back, Side, and Ceiling).

The interesting thing is none of the rooms sound overly 'dead'. Now some are better than others, but none of them sound over-trapped. I dont' know if that's because there are 7 speakers plus a sub all firing away, but I've never felt like it was an anechoic chamber. In fact one of the rooms (I won't say which) needs even MORE bass trapping because if you sit in the couch in the back the sub will knock you over!

Anyway, again sorry for the lack of info initially. The room is still in the 'planning' stage and I was just hypothesizing about using R-38. I've read through some of the threads here and it seems that if the fluffy stuff is 'thick' enough that it works really well for bass trapping. With all the speakers running full range + a sub (I do check bass management, but I don't work with it on all the time) I figured that keeping the the bass controlled was a priority.

Thanks Again for all the reponses.

[Sugarnutz]

You'd have Hi Records/Royal Recorders. The studio floor was nothing but tons if fiberglass in burlap sheets hanging all over the place. Worked for Willie Mitchell. LOL

[DanDan]

Andre has provided links to a couple of 5.1 spec documents in the past.
A search should do it. 5.1 and Andre/Avare.
If your room is for hire, I strongly suggest you hire a pro to design or oversee it. You will find that this process is highly adjustable to your circumstances and budget. A simple room size, treatment location, build handhold would cost less than a microphone.
For free, there is plenty of that at RealTraps GIK johnlsayers.com studiotips.com
If you have a query after studying the field, it is likely to be interesting and educational.
DD

[avare]

Originally Posted by marspe

Yes it will be for 5.1 surround

A very readable document on surround sound is the NARAS P&EW Surround Sound document. A more technical recommendation, which in essence a part of the NARAS document is the AES TD 1001.

Andre

[Glenn Kuras]

Originally Posted by DanDan

Glenn did say IF you have an SBIR issue. If you do, it could be from the side wall just as easily as the front.
DD

Thanks for adding that. I was just going to add that to my post. thumbsup