Building treatment into the walls...

[glennyb]

Hi guys,

i'm a bit of an acoustics newbie, so forgive me if i come off as a bit uninformed on a few things...

Basically, we are building a new control room at the rehearsal studios where i work in the near future. The old one was put together without too much thought for acoustics (despite my protesting) beyond some basic isolation, and so although just about functional, is very far from ideal. Anyway, we are finally ready to build a new one since we have the extra income coming from the old control rooms use (as a teaching facility), and this time we are going to try and do it properly.

I'm currently doing a bit of research to help come up with a design that will make the most of the available space at the most sensible price possible. My initial thoughts about the treatment of inside the room were to build our own treatment, essentially consisting of frames stuffed with rockwool, which we could then hang on the walls/ceiling.

But recently, i've been thinking... since we are going to be building a new floating room anyway, would it not be more sensible to essentially build these traps as part of the internal wall? My initial thoughts were something along the lines of:

concrete shell > air gap > membrane (perhaps roofing felt or some other similar material) > damping (rockwool - and lots, im thinking maybe 8 inches upwards of thickness... we have a ridiculous amount of the stuff sitting around unused) > false wall, consisting of a fabric covering on the top half, and perforated wooden board on the bottom (to stop people kicking/falling through the walls, etc.)

I realize i would lose a fair amount of space using this method, but the space is reasonable, and i would rather have a small working space that sounds good, than a few foot bigger that doesn't.

Does this seem like a reasonable idea, or am i overlooking something?

[Glenn Kuras]

I would highly recommend buying the following book. It will save you a lot of time and money. Even if you hire someone I still would read it to double check what the designer wants to do.
http://www.amazon.com/Home-Recording.../dp/1598630342

[Jens Eklund]

Originally Posted by glennyb

Does this seem like a reasonable idea, or am i overlooking something?

http://www.gearslutz.com/board/7425932-post6.html

[DanDan]

+1 to Glenn's recommended book.
Also Philip Newell's Recording Studio Design.
The idea is totally sensible IMO. Elsewhere it called Inside out. Be careful where you put the vapor layer. Consult builders and engineers. You don't want condensation within the fibre, it will stop working or even worse collapse.
Consider doing half the surface, alternating stripes of framed fibre and hard wall. Place fibre opposite hard.
You would hire pro session musos right?
How about hire a pro acoustician?
DD

[glennyb]

@glenn kuras - thanks for the recommendation, i'll be sure to check it out.

i have read a fair amount of recording studio design by phillip newell, and for the most part it seems to be making sense to me. i've also been through some of the bbc research reports which again support a lot of what it says in recording studio design, and gave me some quite interesting insights into the design of various treatments, and is partly responsible for my main question re: traps in walls.

basically i guess what i wanted to know is if there is any inherent advantage/disadvantage in using a 'false wall' trapping system as opposed to external traps. at the moment its just more of a curiosity rather than being used for any specific plans. i know that it would be variable depending on the room, etc. but logic leads me to believe that a larger surface area and a larger mass with less reflective surfaces would lead to more effective absorption down to lower frequencies... no? could there be too much absorption (is there such a thing?)

just trying to straighten some of these concepts out a bit more basically.

@Jens Eklund

yes i shall be taking note of your advice, but currently im only in the 'getting an idea of what i could possibly do' stage. plus currently the room isn't even constructed so measurements are well out of the question for the moment. as i said above, i guess i'm just trying to straighten some of these concepts out a bit.

cheers guys.

[avare]

Yes, the basic idea of building acoustic treatments right into walls is done all the time. Acoustically ceilings and floors are just walls turned on their side. You can (not) see such in treatments in many professionally designed studios.

The design factor to bear in mind is the TL requirements of the wall when designing it with the treatments.

Have fun designing a great space!

Andre

[glennyb]

Originally Posted by DanDan

+1 to Glenn's recommended book.
Also Philip Newell's Recording Studio Design.
The idea is totally sensible IMO. Elsewhere it called Inside out. Be careful where you put the vapor layer. Consult builders and engineers. You don't want condensation within the fibre, it will stop working or even worse collapse.
Consider doing half the surface, alternating stripes of framed fibre and hard wall. Place fibre opposite hard.
You would hire pro session musos right?
How about hire a pro acoustician?
DD

Cheers DanDan, its nice to have a name for the system so i can have a look for it now! With regards to the vapour layer... you mean the covering i assume (as opposed to the internal membrane)... i will definitely take that into consideration if this is what we end up doing.

As for the alternating hard wall/soft wall, would this be to keep absorption down for the higher frequencies so as to not over-deaden them? or for cost reasons? basically, like i asked earlier - is it possible to have too much absorption (im more interested in a non-environment control room as opposed to a live end dead end style).

And yes i'd love to hire a pro but its gonna be enough of a headache to persuade my boss to shell out for the extra materials as it is - we are only a small business and our main revenue comes from education, not commercial recording.

[glennyb]

Originally Posted by avare

Yes, the basic idea of building acoustic treatments right into walls is done all the time. Acoustically ceilings and floors are just walls turned on their side. You can (not) see such in treatments in many professionally designed studios.

The design factor to bear in mind is the TL requirements of the wall when designing it with the treatments.

Have fun designing a great space!

Andre

Thanks Andre...

Could you possibly elaborate on the 'TL requirements of the wall' part of you post?

I assume TL means transmission loss? Is this referring to isolation properties, or am i misunderstood?

[avare]

Originally Posted by glennyb

Thanks Andre...

Could you possibly elaborate on the 'TL requirements of the wall' part of you post?

I assume TL means transmission loss? Is this referring to isolation properties, or am i misunderstood?

Yes TL is Transmission Loss.

You are using great reference material and congratulations on masterng my signature line! I forgot to write that in my previous post.

Andre

[DanDan]

I meant the Vapour Check Layer. I believe it is normally as close to the cold side as possible, but do check with thermal experts.

I am not sure where Inside Out is used, but most likely at studiotips.com or johnlsayers.com. Two great sites.

It is possible to have too much or more accurately an inbalance of absorption.
50% of the walls and ceiling covered with 8 inch deep strikes me as plenty of MF and HF absorption. Bass requires enhanced designs. Look at the size and complexity of Newell's Back Walls and Ceilings. Very deep, Hangers, Limp Membranes.....
I have great hopes for the VPR My Experiment with a Metal Panel Absorber

You might be surprised how flexible and affordable us Acousticians can be.

And thats not a Trap......

DD