Temporary drum room in my 13.5'x15' bedroom

[witulski]

We're fairly rabid do-it-yourself recordists and have elected to make a debut album of our nrrd-rock trio on our own. I'm pretty happy with the equipment we'll be using, and I think we'll get a modest if not top-of-the-line product as far as guitars, vocals, and whatever else... however, I'm a little concerned about the drums.

The kit is a Rogers four-piece from the '70s, with a light little 20" kick that has a cool stab sound. The toms sound good, the snare is iffy (we're working on heads for that) and the metal works well.

The microphones all go dry into the 8 inputs on an Akai DPS16. They are:
Kick-Beta52
Snare-SM57
Hat-SM81
Rack tom-SM57
Floor tom-SM57
Ride-SM81 (on order)
Overheads: 2 AKG C1000S's.

Lately I've become concerned about the sound of the room and how it contributes to the drums. The drums are currently against the middle of one of the short walls of a long basement room, estimated dimensions 13x45. The floor is carpeted, the walls are bare drywall, and the ceiling (about 7") is drop-ceiling tile. I was beginning to get the feeling this wasn't contributing to the sound.

My bedroom in my rental house is 13.5'x15' with a 9.5' ceiling. I'm considering building a ~8x10 room in part of it, using the floating floor and separated studs ideas I've come across on this forum only in the past few days (following more research, of course.) However, if I moved into the basement for a month or so, I could really take over this room and start using most of its space. Would the extra space make that much difference in the sound if everything is close-miked? For that matter, with all that close-miking going on, is the current long basement room making that much of a difference?

I'm sure I'll have more questions, but for now I'd like to know about this room size. If I'm gonna be sleeping in the basement I gotta go get some ant traps.

Thanks, great forum!
greg

 

[knightfly]

First, close-micing will only lessen the effects of a bad room, not eliminate them - there's no substitute (only band-aids) for a well-proportioned room. They require less treatment, and sound better with no treatment than some rooms will EVER sound, no matter what you put in them.

The good news is, you should get some ant poison - the modal response of that 13.5x15.9.5' room is nearly perfect as is. If you reduce it to 8x10, with a 9' ceiling (floated floor) the modal response looks good til you get up to 282.5 hZ, where the 4th harmonic of height and the 5th harmonic of length are equal. Having two different dimensions that are causing identical harmonics will color the sound (boost at that frequency) which, below 300-400 hZ is noticeable in the sound. Above that range isn't as bad, since there are more room modes closer together (octave-wise)

If you're not seriously concerned with sound leakage (both in and out, since it's a two-way street) I'd go for the larger room volume with more even response.

If you build a room-in-a-room with walls that close to the new walls, it won't be nearly as effective at stopping sound as it would be if you could remove the inner wall covering of the room, add Resilient channel, and put at least two layers of 5/8" sheet rock over the channel, sealing EVERYTHING with acoustic-rated caulk.

I doubt that you have that option, unless you're renting from your own sweet, doting grandmother and she's senile :=) - but I'm just saying, don't think you'll get total silence by building a room inside the one you have.

Whenever walls are relatively close to each other (maybe 3-4 feet or less) you need to stick to a system that has only two centers of mass (leaves) with only one air space between them - this is BY FAR a more efficient use of materials/mass. Case in point - if you were to build two standard stud walls, with sheet rock on both sides of two stud frames, each insulated, AND you sealed them totally, you would get an STC rating of about 40 dB (about 12 dB better than just one wall) Then, if you REMOVE one of the inside leaves the STC IMPROVES - if you remove the OTHER inside leaf, the STC IMPROVES AGAIN - finally, if you put the two layers that were removed BACK but this time, as second layers on each of the OUTSIDE leaves, you end up with a total improvement of 22 dB !!!

Bottom line - if you can live with the sound PROOFING you have in that room already, it will be hard to beat the sound QUALITY. Just add some bass traps in the corners, maybe set the drums up on a couple sheets of 3/4" plywood, put some rigid fiberglas (not foam) insulation on the ceiling and a few scattered pieces on the walls, watch mic placement (phasing cancellations can happen at high freq's with just a few mm movement of one mic) and you should be there.

If you find your getting too much noise in your overheads, I'd look at replacing those 1000s's with maybe a matched pair of the Rode's for $299, or putting the SM81's on overheads and the Rodes on hat and cymbal... Steve