Use of RC for stopping low frequencies ?

[wolf_of_badenoch]

Still thinking about my drum practise room. I have been investigating resilient channels and found that I can't find any in Australia. The nearest that I can find is resilient mounts with furring channels (great name).

http://www.gyprock.com.au/technical/tec ... v2.psd.pdf (page 4 for those who are interested).

My problem is that from reading a lot (but not all) of the posts on the subject here, I get the impression that RC isn't really helpful for low frequencies, and hence may not be the best spend of my dollars. I'm sure this stuff is as cheap as chips in the US, but here in Australia I have been quoted $4-16 per mount, and $8-61 for a 4.8m length of the furring channel. There is also another metal track required at the top and bottom of each wall. Didn't get a price for that. I calculate that I'll need around 50 mounts to do a drum room somewhat less than 2.3m in each dimension, so the cost of the mounts plus the furring channels is going to come out around $300. Now, that is a fairly significant chunk of money, and I am not sure whether it would be better to leave it, see how my room turns out, and if necessary add a second external leaf of gyprock with that money.

Any expert opinions out there ?

[knightfly]

The RSIC clips run around $5 each here, and the channel is similar; but for drums, I think they would be a waste of money; I would put that money into more mass instead, and if possible increase the footprint size of your room enough to build walls that total 250 mm thick - this would be TWO layers of 13mm gyprock each side, the inner and outer layers on their own SEPARATE framework. Use either 70 or 90mm studs for each frame, using the techniques that are all over this board for caulking, etc -

fill with fiberglass insulation between frames, to the point that the insulation is slightly compressed by the wallboard (helps damping) - with a total air gap (inside of the outer panels to the inside of the inner panels) of 200mm, you would end up with about STC 66, with a TL of around 32 dB at 50 hZ; this would mean that the neighbors would get around 25 dB louder than silence if you were playing at full volume -

I'm not familiar with your local noise ordinances, but this shouldn't cause problems if they are sane. Lawnmowers put out about 4 times that amount of noise... Steve

[wolf_of_badenoch]

Steve,

Thanks (as always) for spending your time replying to my questions. I will probably try and do as you say. One thing I'm not clear on - it may be that I have missed it (there is an AWFUL lot of info on this site ), is exactly how to keep the inner and outer framework apart. Obviously in the walls themselves this is easy, but when they connect to either the floor or ceiling I am not clear how to do this without a connection from inner to outer being made. Eg for the ceiling, what can the outer wall connect to that the inner wall doesn't connect to

I've had a look around here for some design drawings, but the best I can find is http://www.johnlsayers.com/phpBB2/viewt ... c&start=30 and that doesn't really answer the question of how to keep the inner and outer frames completely seperate ?

Thanks again Steve for your help.

[wolf_of_badenoch]

Hmm, having reread your post a bit more carefully I doubt that I will have the ceiling clearance to do this - I'm going to have to be imaginative enough in my ceiling construction inside the garage anyway. I presume that I could build one stud wall with gyprock and insulation and if this still wasn't enough, build another one around it later when funds are permitting ?

cheers.

[knightfly]

No, you need to plan ahead so you don't end up spending time and money in order to make things WORSE - you need two areas of MASS, separated by one air/insulation gap, PERIOD.

If you're on a budget, you need to make sure the outer mass is solid, then build a frame for the inner mass, insulate fully and put up however many layers of gyprock you can afford, then when doors/etc are complete and sealed as best you can, do a sound isolation check (beat the drums, have someone (preferably your most picky neighbor :=) LISTEN from their location, and if they're happy you're DONE -

If they're NOT happy, at least they know you're trying; and you still have a place (the innermost surface) to add MORE gyprock, with NO MORE air spaces; another likely area would be door seals - these are hard to do. A second door with an air lock will make a BIG difference here... Steve