John Sayers' Recording Studio Design Forum Archive

I have found this site to be of great assistance in determining how to soundproof the room; however I have been going in circles when it comes to determining what I should do to improve the acoustics (base traps, helmholtz resonators, etc) in the room. The room is for my daughters to practice/rehearse their music (guitar/drums and vocals). The attached image displays the room and it is located in the basement of my house. The gray border represent the poured concrete wall. The room will have double walls going around it The smaller room is for now a closet, but it will be prepped (electrical, etc) for potential future use as a control room. What I would like are some recommendations on:

1) To improve the acoustics what should I build (base traps, helmholtz resonators, etc) and where to locate them?
2) What would better for the floor. Cork, engineered hardwood, or other and why?
3) I've read about sand filled drum risers, and also Auralex has a drum platform product. Is there any benefit to any of these? If so which one and why? Is there something else I can do to help handle the drums?

Thanks

SNS, first welcome to the board; second, sorry for the delay, it's been a typical week - now, to your questions -

1) To improve the acoustics what should I build (base traps, helmholtz resonators, etc) and where to locate them?

Before I can do much with this one, I need better definitions of YOUR version of "double walls", an idea of what your ceiling consists of, and what your floor is at the moment - all these will affect the room's response, therefore the need for treatment.

2) What would better for the floor. Cork, engineered hardwood, or other and why?

Concrete (this can be stained for an interesting effect) and hardwood are a bit brighter than cork, which can work FOR you when using quite a bit of broadband absorption to bring down mid-range reverb (this will also bring down the highs)

3) I've read about sand filled drum risers, and also Auralex has a drum platform product. Is there any benefit to any of these? If so which one and why? Is there something else I can do to help handle the drums?

With your limited headroom, the lower the riser the better as far as habitability is concerned; however, from an isolation standpoint you need as much mass as you can get, separated from structure (your main floor) by as much air gap (filled with insulation for damping and better isolation) as you can get, in order to get the overall resonance of the system sub-audible in frequency -

For COMPLETE range isolation, it would take at least 4" of concrete with at least 6" damped air gap, resting on typically 1" thick elastomer blocks spaced so as to compress them to around 10% of their total thickness - However, this would require losing around 11" of ceiling height just for the riser;

A sand-filled riser, due to the damping properties of loose sand, would not tend to "ring" without the extra air/insulation between the riser floor and the main floor; it would also not have as good isolation, especially if you rest the floor framing directly on the main floor; better if those joists were on the same elastomer blocks (EPDM or neoprene have similar acoustic properties, but neoprene will be at the end of its useful life in about 10 years, while EPDM typically lasts more like 25. Yes, the EPDM is more expensive...

Total height of a workable sand-filled riser might run around 6-3/4" - 1" rubber(with rockwool or fiberglass between rubber pucks), 3/4" OSB, 3-1/2" joists, and either one layer of 1-1/8" T&G ply or two layers of 3/4" OSB, with the joist cavity sand-filled.

This would make a solid, low-resonance riser but would NOT have as much isolation to the rest of the house, due to the narrow air gap below the floated mass - rough calculations show a mass-spring-mass resonance of around 30-35 hZ, which would be its weakest point; good isolation wouldn't happen until frequency was about 2 octaves above that, so there would still be some LF bleed into structure from the drums.

The deeper, floated concrete version above, by comparison, would have a resonance at around 13 hZ, so would isolate pretty much anything you could hear from the rest of the structure.

Then you have the walls -

The concrete portion (assuming it's backfilled with dirt on the other side) shouldn't cause the neighbors any grief, but will still FLANK any sound made in the room through all solid structure, and can re-radiate ANYWHERE in the building by wall/ceiling/floor panels which are attached firmly to framing; these panels become "speakers" in effect, and this flanking phenomenon can skip entire floors and pop up in an attic room, or just radiate EVERYWHERE; without testing, it's nearly impossible to predict WHERE or how BAD this will be.

The way around that is a complete, floated, room-in-room construction - this has been done so successfully (with enough $$$) that an ear-splitting DISCO resides in an OFFICE building (in Switzerland IIRC) and the office workers hear nothing (place is called "Mad Max", built by WSDG out of Texas)

A lot of this depends on your level of tolerance, and that of the neighbors; If you can give a better idea of that, and a more in-depth description of your EXACT existing construction (and BUDGET), I can probably come closer to figuring out what should work for you... Steve

Thanks for the reply. First off the basement concrete walls are backfilled with soil and only the top foot is above grade. This includes the 2 * 10 ceiling joints. The walls that I am constructing will be as follows:

Outer walls backing onto concrete, excluding the closet are:
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Outer walls backing onto concrete in the closet are:
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound
1 layer of 5/8 Gypsum board

Side 9' 8" walls:
1 layer of 5/8 Gypsum board
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Bottom 18' 11" wall. Opposite this wall is the staircase leading upstairs.
1 layer of 1/2 Gypsum board
2 * 6 wood studs 16" on center filled with 6" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Ceiling
2 * 10 wood studs filled with 2" air space and 6" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Floor
The basement floor is your basic poured concrete floor. Currently leaning towards installing cork flooring.

Doors:
The entrance doors will be two exterior grade insulated steel doors. The ones that come with complete with weather-stripping etc.
The closet entrance will be a single exterior grade insulated steel door

Window
The room has one small window, 32" wide and 12" high which is sub-grade and in a window well. I will be constructing an insert that will be placed in when they play. It will be made of the following: 5/8 plywood 3" Roxul Safe and Sound and another 5/8 plywood with weather-stripping around the edges.

Drum risers
My main concern is the lack of height in the room; especially if I place any acoustical treatment on the ceiling. That is why I found the auralex platform product interesting. I know it's rare, but sometimes the easy way does work. Any experience/opinions on the product? Here's a link

http://www.auralex.com/sound_isolation_ ... atfoam.asp

Soundproofing Questions:
- Would increasing the amount of air space from one to two inches be beneficial?
- I've read conflicting points in regard to the use of resilient channel in a drum room. Should I use the resilient channel?
- Would it be beneficial when doubling up on insulation to use different types? For example instead of 2 layers of 3" of Roxul Safe and Sound have one layer of Roxul Safe and Sound and one layer of Roxul 3 1/2" batt insulation?
- Would it be beneficial to double up on the doors to the closet area as well?

Overall Goal and Budget
The overall goal is to have a room where my girls can rehearse while causing minimal disturbance to our neighbors. There is no set budget, as my lady has informed me spend what you need to spend, but like everyone else I would like to spend as little as possible. What helps is that I will only need to pay for materials, and for the electrical work. I am also hoping to be able to construct the acoustical treatments that you suggest if at all possible.

Outer walls backing onto concrete, excluding the closet are:
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Since your inner stud frame is separate from the outer wall, no RC is necessary; also, 24" centers work just as well for stud spacing if you want to save a few $ and make insulation easier. This inner frame should NOT be in direct contact with your ceiling joists however; some type of resilient SWAY brackets should be used instead wherever the wall needs top support, and a gap should be left between ceiling joists and the top plate of at least 1/4", otherwise sagging of the joists could cause flanking noise from the inner wallboard into the wall frame, up into ceiling joists and to the rest of the house.

Outer walls backing onto concrete in the closet are:
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound
1 layer of 5/8 Gypsum board

If these studs will contact the concrete wall, then RC SHOULD be used here; if you're planning on that being a Control Room there should be double 5/8 on RC; 24" centers on studs, 16" centers on the RC, bottom RC 3" from floor, then 1 RC 2-3" BELOW the 48" level and 1 RC 2-3" ABOVE the 48" level, continue @ 16" centers elsewhere. This will support up to 3 layers of 5/8 drywall, and if you stay with 16" STUD centers the RC can go on 24" centers; but keep the RC's @ 2-3" from each 48" line, so each panel will have edge support; you can NOT attach two ADJACENT panels onto ONE RC without botching it. The fastening surface isn't wide enough. For more on drywall, check the COMPLETE section thread, located in the REFERENCE section at the top of the Construction Forum.

Side 9' 8" walls:
1 layer of 5/8 Gypsum board
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

Again, no RC needed here with separate frames.

Bottom 18' 11" wall. Opposite this wall is the staircase leading upstairs.
1 layer of 1/2 Gypsum board
2 * 6 wood studs 16" on center filled with 6" Roxul Safe and Sound.
1" air space
2 * 4 wood studs 16" on center filled with 3" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

I need to see a sketch of what goes where for this wall; including the staircase, any door or other mass involved with either the bottom or top of the staircase, how the stair risers attach to framing, etc; you may not need RC here either, but a detailed sketch will be necessary to know for sure. Staircases are usually built for sturdy, NOT for sound isolation so this can make a big difference in the amount of sound reaching the rest of the house.

Ceiling
2 * 10 wood studs filled with 2" air space and 6" Roxul Safe and Sound.
Resilient channel at 24" on center
2 layers of 5/8 Gypsum board

This is one place, assuming those are the common joists to your upper floor, where the RC WILL be necessary; this sketch, other than the dark brown parts, shows the order and placement for most of your walls/ceiling -

http://www.johnlsayers.com/phpBB2/download.php?id=4316

Floor

The basement floor is your basic poured concrete floor. Currently leaning towards installing cork flooring.

If you do the drum riser, this should work fine; I'd leave enough extra room on the riser for any bass amps that may find their way into things.

Doors:

The entrance doors will be two exterior grade insulated steel doors. The ones that come with complete with weather-stripping etc. The closet entrance will be a single exterior grade insulated steel door

Should be fine.

Window

The room has one small window, 32" wide and 12" high which is sub-grade and in a window well. I will be constructing an insert that will be placed in when they play. It will be made of the following: 5/8 plywood 3" Roxul Safe and Sound and another 5/8 plywood with weather-stripping around the edges.

If the window glass seals well, you would actually get better isolation by putting BOTH layers of ply at the INSIDE, then allowing the insulation to protrude slightly beyond the SIDES of the insert frame so that the insulation gently touches the window when the plug is inserted;

This is because even a tiny air gap between the plywood close to the glass will turn the assembly into a 3-leaf wall, and that will hurt low frequency attenuation. You would actually get better isolation putting ALL additional mass at the inside, and allowing the GLASS to be your outer leaf.

I know at least one thread here says otherwise; I've since learned why that's not a good idea. Just haven't had time to edit the older stuff.

Drum risers

My main concern is the lack of height in the room; especially if I place any acoustical treatment on the ceiling. That is why I found the auralex platform product interesting. I know it's rare, but sometimes the easy way does work. Any experience/opinions on the product? Here's a link

http://www.auralex.com/sound_isolation_ ... atfoam.asp

That's probably the least hassle way to get some isolation; I didn't see any actual figures, but if you do that I'd go with the heaviest platform floated on the platfoam that you can; something like two layers of 5/8 OSB with a layer of 3/4 particle board or MDF sandwiched between. Mass is your friend here. May want to follow Auralex' recommendation on the carpet as well.

Soundproofing Questions:

- Would increasing the amount of air space from one to two inches be beneficial?

By that, I'm assuming you mean the 1" space between inner and outer wall frames? If so, the answer is "not much" - the effective air space is that between your inner wallboard surface and the inside of the outer wallboard surface; so 2x4's twice = 7", plus 1" air gap between frames gives an effective air/insulation gap of 8" - adding an extra inch will change this from 8" to 9". This would improve LF TL by about 1 dB @ 50 hZ, and no change at higher frequencies (2 x 5/8 gypsum each side of double 2x4 frame)

- I've read conflicting points in regard to the use of resilient channel in a drum room. Should I use the resilient channel?

The only place RC will benefit is when there's no OTHER way of decoupling your inner wallboard from structure; I outlined above where it should and should not be used, this is based solely on whether the frame the wallboard is mounted on connects directly to main structure.

- Would it be beneficial when doubling up on insulation to use different types? For example instead of 2 layers of 3" of Roxul Safe and Sound have one layer of Roxul Safe and Sound and one layer of Roxul 3 1/2" batt insulation?

Within a wall, even insulation DENSITY doesn't seem to make a lot of difference; it's more With or Without that matters, typically 6-10 dB difference. Other than that, a slight compression fill (VERY slight with the higher density stuff) damps the wallboard panels without decreasing the decoupling between them. If cost is a factor, and you can get UN-faced standard fiberglass batts, those can be used to finish filling wall cavities - main thing is to end up with slight pressure against inside wallboard surfaces, but NOT enough to cause an increase in coupling between them.

- Would it be beneficial to double up on the doors to the closet area as well?

If you're planning on recording, and want to be able to set mics by listening to the SPEAKERS,(instead of all the BLEED coming through the door/window/wall) and you will have either double pane glass window OR CCTV gear so that ALL the closet is separated by double leaves, then yes... Steve

Thanks for the quick reply. So far It appears that I'm not too far off track in regards to the soundproofing. The area that causes me the most confusion/concern is the acoustics. To improve the acoustics what do you recommend I build (base traps, helmholtz resonators, etc) and where do you recommend I locate them?

I just ran a modal distribution of your room, and believe it or not it isn't that bad; just a bit of a "hole" around 30-50 hZ, might not even notice that.

Simplest "first" thing to do would be to get some 3 or 4" rockwool (like Roxul safe and sound) and place 3' wide batts across any and all corners you can, including at least a few wall/ceiling corners; then, more of it suspended a couple inches off the ceiling over the drums so micing them won't get you a big phase cancellation thing going from overhead mics. 2x2 patches of the same stuff placed opposite bare spots on opposite walls to control flutter, again spaced off the wall by a couple inches if possible.

After that basic treatment, if you still have hot spots you might need to consider panel or helmholtz absorbers; some rooms don't need them at all. Best to do just the simple stuff first though; no sense building stuff you don't need... Steve

gonna bump this because I am using the info for my space.

Or, you could just bookmark the thread so you can find it a month or more from now