Rutgar

Sanker, it's my understanding, that building a "room within a room", and using "acoustiblok" will help in sound proofing, but won't do a thing to help with room acoustics. Using Resiliant channel is for bass management, not sound proofing. In other words, you still need the resiliant channel, even with the acoustiblok, and double studs. Like I suggested earlier, buy the book, "Premium Home Theater" Design and Construction by Earl Geddes. It tells how to properly install the channel without "shorting" it out. Plus, it explains the physics involved with rooms, and low frequencies as well.

- Rutgar

Sankar

Thanks Rutgar.
I had read a fair bit about resilient channels on the internet (e.g NAIMA,SoundProofing,Acoustics101,ACS ISO-Wall, etc) and my understanding was that it too was designed for sound proofing by providing a flexible separation between the drywall and frame (assuming that we avoid the infamous "shorting" problem!). However, I must confess that I did not read the book by Earl Geddes ... is it there that he makes explicit mention that resilient channels also assist in bass management?

Its probably too late for me to go for resilient channels now and I may be forced to go with conventional approaches to bass management such as my trusty BFD and bass traps. I wish I had read Earl Geddes' book --- my primary sources were Alton Everest's "Master Handbook of Acoustics" and "Sound Studio construction on a Budget" where he makes no mention of resilient channels (not even for sound proofing). He does discuss the physics of porous and resonant absorbers though.

Rutgar

Again, according to Geddes's book, the main idea behind resiliant channel is low frequency absorption, without killing high frquencies (high frequencies are what give the room "perceived spaciousness", which is why you don't want to "kill" them). The moving wall dissapates energy through friction (All absorption is friction of some sort). With resiliant channel, absorption decreases with frequency. In other words, the higher the frequency, the less absorption, the lower the frequency, the more the absorption. Large sound absorption at low frequencies help to smooth out low frequency response irregularities. Which, in turn, gives a small room smooth clean bass.

I think you really should go ahead and add the resiliant channel, and another layer of sheetrock. I know it might mean that you have to back track a little, but it would be well worth the effort. Like I said before, according to Geddes, you only have to have it on one opposing wall for each of the three pairs, for it to work.

- Rutgar

Sankar

Thanks again Rutgar!

I'll try and see if I can get the contractor to install RCs. So Geddes' point is that only 1 wall need be set up with RC? i.e. of the 5 available walls (sides, front6, rear and ceiling)?

Rutgar

It must be one of each parallel opposing wall. In other words, when finished, you will have RC on three walls. for example: the ceiling, the front wall, and the left wall.

And one other thing, you must be careful to not "short out" the sheetrock mounted on the RC. Do a search on RC on the web. There are several sites that talk about how to properly install RC.

- Rutgar

Sankar

Thanks again. That would be consistent.
I have read about RC quite a bit ... the "shorting" issue relates to sound isolation right? At least that's what all the web sites I listed earlier indicate. If my understanding of how this is supposed to work is correct, it would appear that the bass trapping ability is unaffected *even* if there were some shorting involved (since its the flexible vibration of the sheetrock that reduces its reflectivity of bass frequencies). Admittedly one should avoid the shorting problem, but since I already have a room within a room + acoustibloc, I would guess that I am less concerned with the sound blocking ability of the RC (which would be nice of course).

Has anyone else had experience with the bass trapping ability of resilient channels? A second opinion would be nice before I go to war with my contractor at this late stage of construction :-)

I did not have any luck in finding the book at Amazon or Barnes and Noble . I did find Geddes' website and the book can be purchased there (unfortunately I do not have the luxury of stopping construction for a week to have it shipped etc ...). For those that do have time on their side, the website is http://www.gedlee.com .

Sankar

Rutgar ... I think that I will try and see if I can convince my contractor to hold off a couple of days and install resilient channels on the walls + ceiling. You have indeed gotten me thinking now

In the absence of Geddes' book (it is only available through the web site and that will take a few days to reach me), could you advise me if the RC MUST be only put on one of the parallel walls or whether I can put in on all of them? If I am going to put RCs then I may as well go all the way since the extra cost is not that high. In other words is it better (purely from the bass absorption perspective) if I were to put it on the 2 side walls, front wall, rear wall and ceiling (not on the floor!)?

Are resilient channels available through Lowes, Home Depot etc or are internet suppliers the only reliable source?

Thanks

Ethan Winer

Sankar,

> Has anyone else had experience with resilient channels acting as bass traps? <

A sheetrock wall with resilient channel will give more bass trapping than a rigid sheetrock wall. However - and this is a big one - the trapping will be effective over only a fairly narrow range of low frequencies. All rooms need substantial absorption at all low frequencies, so in the larger picture an RC wall is not an effective bass trap.

--Ethan

http://www.realtraps.com
The acoustic treatment experts

Sankar

Thanks Ethan,

Actually, I was not planning on relying on the RC completely. I'm sure that I'll have to add acoustic treatment once the room is built. However, the option of including resilient channels will not be available at that juncture. Hence my thinking is that if the inclusion of RCs now makes bass management somewhat easier later, then it may be worth giving it a shot.

Question is whether I should put it on all 4 walls and ceiling or should I just put it on 2 adjacent walls + ceiling ...

Steve::Weaver

Okay, I'm a relative newbie, not audio engineers like you guys but couldn't there be additional cancellation problems caused by both the mains and the subs puting out bass?

Mike, have you tried crossing over your mains higher to see if that helps?

Ethan Winer

Sankar,

> my thinking is that if the inclusion of RCs now makes bass management somewhat easier later, then it may be worth giving it a shot. <

Yes, it can only help - even if just a little - and the more surfaces you treat that way the better.

--Ethan

http://www.realtraps.com
The acoustic treatment experts