John Sayers' Recording Studio Design Forum Archive

I apologize in advance for the length of this post – but I figured more info is better. If I’ve missed anything, please let me know.

I’m trying to determine my next step to setup what will be primarily a production/mixing environment. Room diagram attached (dimensions to scale – however desk/speaker position may not be represented exactly).

Details:
4 – panels (labeled ‘traps’ for sake of space) 4” thick 705, 2’x6’, in wood frame, covered in front w/ burlap, rear is exposed (no alum face).

2 – panels (2’x4’, 4” thick, in wood frame, 8 lb. mineral wool) covered with cloth.

Room dimensions are 10’8” x 10’0” x 7’8”H. I set up facing the “long” wall (figured I’m just about in a cube) because placement of treatment is problematic due to the entrance and closet doors on what I’m calling the ‘rear’ wall behind mix position. I figured I could more easily move traps on the rear wall. I’m in an apartment – and only plan on being here about another year so any permanent (non-portable) or major construction is not an option. I’ve indicated the position of the 6 traps. The 2 rear corner traps are the 2’x4’ panels as they are easiest to move and would be positioned there only when mixing.

I will do no live tracking in this room except VOX (if the room is a little more ‘dead’ that’s ok – I’m not trying to capture room ambiance and would cut VOX as dry as possible). So, it is primarily set up to compose, produce, and mix.

I positioned speakers (all freq settings flat) and mix position using the method pointed out here which uses the mode calc spreadsheet and drawing a grid to find out where the nulls and peaks are. I do not have a mixing console and my work-desk extends only 11” from front vertical plane of the speakers so I’m assuming I don’t have too much of an issue with reflections from the desk. Floor is carpeted with pretty thick padding underneath (don’t have details – doubt the landlord does either).

I’ve shot the room w/ pink noise at 85db SPL c-weighted at the mix position with a behringer ecm 8000 measurement mic (it was lent to me and I’m assuming it’s better than the mic in the radio shack SPL meter and has a more flat response than a LDC). I’ve attached images of the response curve created using Inspector XL, also set to C-weighting (I’m on a MAC – if there’s a better, relatively inexpensive app out there – please let me know – Spectra Foo is hard to $justify$ given the amount of analysis I’ll be doing).

So here are my questions:

1. On the EQ curve – it looks like I still have work to do taming the bass, but would appreciate an expert’s interpretation of the results. Based on the treatment I already have, what’s my next best step – the ceiling? Or, more in the front? (seems that the curve smoothed out after I put the middle trap up front).

2. Also on EQ curve, I’m curious about the spikes & dips in the 300Hz-600Hz range - any ideas as to the cause and how to best deal with it?

3. Would I benefit from any type of diffuser? Or Helmholtz resonator? I’m assuming that before I add diffusion, more absorption is warranted (and I have to admit I’m a little leery of building a Helmholtz resonator as I’ve read that if not done correctly it can create as many problems as it was intended to fix).

My budget is somewhat limited - I can spend another $200-300 right now but have to do this in steps since this project is also affected by the girlfriend tolerance factor, which, due to it's unpredictability was not represented in any of the diagrams.

Any thoughts or suggestions greatly appreciated.

In the front corners I would go floor to ceiling with bass traps, also you may want to straddle ceiling to wall with a few panels to help out. Really the trick is "MORE IS BETTER" and with a room like yours you are just going to need more.
I don't see any panels for the first reflections so I would put a panel on the left wall and right wall in the first reflections. Also a couple panels above the mix position will do wonders for you.

Glenn

Thanks, Glenn.

Will 2" or 3" thick panels work for the L & R walls and the ceiling or should I stay w/ 4" thick?

Jeff

In your room, 4" panels all the way around is the right prescription.

You'll hear the same thing from everyone here. Treat your front and rear wall/ wall 90 corners with 4" thick broadband absorbers on a 45 degree angle. (Again, straddling the wall/ wall corners. you knew that already, didn't you?

However, if getting multiple panels in your vertical corners is not an option (for any of the vertical corners) try 6" of 3lb density mineral fiber for more absorption. I've determined this to be a good alternative to just a 4" thick panel in restircted (gear filled) corners.


Also, don't over treat your space. What? That's right; there is a point of diminished returns wherein adding more panels (spending more money) does not mean measured improvement in your acoustics. I think you'll see a very nice change in your room acoustics at around 12 panels (48x24x4)
A few more might not be a bad idea.

Good luck mate!

I'd agree that in that room, something thicker might be a good idea. Just remember that by the time you do 6" thick straddling panels, the same amount of material will make solid corners floor to ceiling.

Don't get me wrong, if you need to frame them and straddle, 6" of 703 is an excellent absorber.

Bryan

bpape wrote:I'd agree that in that room, something thicker might be a good idea. Just remember that by the time you do 6" thick straddling panels, the same amount of material will make solid corners floor to ceiling.

Don't get me wrong, if you need to frame them and straddle, 6" of 703 is an excellent absorber.

Bryan

The point I was making is that if any of his vertical corners cannot accept floor to ceiling treatment, that 6" of OC703 in a 48x24 configuration is a good alternative to just a single panel of 4" 703 in that same space. Infact, the minimum amount of additional absorption would be 11% beyond that of a single 4" panel, and perhaps more.

Also, 6" of OC703 (in a 48x24" config) would not be enough to evenly treat a floor to ceiling corner.

Agreed Joel.

I wasn't considering a 24x28, I was looking floor to ceiling (or just the same height). 6" of 703 for a 24x48 will make a solid corner 48" tall.

Bryan

Thanks everyone for the input. I have come across some pretty inexpensive 2.5pcf mineral wool (see SAFB under FIBREX on bob golds site: http://www.bobgolds.com/AbsorptionCoefficients.htm) in 2" and 3" thickness so building some 6" panels, and additional 4" panels shouldn't be too much of an issue.

However, the problem I'm going to have is that the Left side wall has a radiator inbetween the window and 'front' wall. Sorry - probably should have drawn that on the first diagram (but had had enough of MS Visio - I've attached a new drawing).

So, floor to ceiling and 'flush' against each wall in the front can't happen unfortunately. I can either go floor to ceiling but slightly further out from the left wall (see diagram - and I'm assuming for symmetry purposes would want to do the same on the right side). Or, I can put a 6" thick, 2'x4' panel in each corner flush against the L/F & R/F walls (with the left panel above the radiator). Any suggestions on which way to go appreciated.

I'll keep the rest of the panels based on the advice above a mininum of 4" thick - and as it's going to turn out will probably end up with about 10-12 panels when all is said and done. Thanks again for the help!