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Sugarlander 6th June 2009 03:03 AM

Questions about room treatments
This is my first post. I’ve read a lot and learned a lot from the very knowledgeable people on this forum, including Ethan and his site. Nevertheless, I am confused about some decisions for room acoustic treatments would like to ask for some help from you.


I have an empty bedroom that I want to turn into a “MUSIC” room with these uses in order of priority:
1) playing acoustic guitar and vocals
2) listening to stereo music (audiophile stereo system)
3) self recording of acoustic guitar & vocals (desire to get near-professional results)

There will be no other uses (no bed or furniture, etc. in it except for music related stuff.)

The upstairs room is 11-6 ft wide x 14 ft long x 9 ft high ceiling. It is finished with sheetrock on walls and ceiling and has carpet flooring. Walls are 2x4 wood framed with fiberglass batt insulation. Sound proofing is not a concern. One arched doorway is on one 11-6 wall and one 5 ft long x 4 ft high window is on the opposite 11-6 wall. The 14 ft long walls are 7’-10” high and quickly slope up to 9’. I could put in a wooden floor if absolutely necessary or, as Ethan suggested, lay a couple of 4’x8’ sheets of plywood or over the carpet where I play and record.

From reading it appears I would sit about 38% (5’-4”) off from the window or 8’-8” off the window (38% from the back entry wall). I’ll put and open legged flat table in the room to put my laptop computer and minimal recording equipment on. I’ll put the stereo equipment in a rack between the speakers on the window wall.

My budget is $1,000 for room treatments to improve the acoustics. I am good with DYI projects and technical things, but my time is valuable. I have considered just buying panels outright, but I see that I can get a lot more treatment if I did even a small amount of work. I’ve gotten pricing from a local source here in Houston for insulation. The pricing is much better than what I have seen at the acoustic specialty companies offering raw insulation. Here are the prices I’ve gotten:

OC 703 Fiberglass 2’x4’x2” 3#/cf density $10.21/sheet
OC 705 Fiberglass 2’x4’x2” 6#/cf density $18.62/sheet
Fibrex mineral wool 2’x4’x2” 6#/cf density $ 5.20/sheet
Fibrex mineral wool 2’x4’x2” 8#/cf density $ 6.06/sheet
Fibrex mineral wool 2’x4’x4” 4#/cf density $10.21/sheet

Obviously, high density Fibrex priced this low is very attractive for a DIY project. 3 sheets or 6” of Fibrex is cheaper than one sheet of the same density Owens Corning product. I’ve considered the easy DIY project of $27 Ready Bags with 6” Fibrex ($15.60) for $43 for each 6” broad band bass absorber that is open on all sides. My budget would allow for about 23 of these. Of course, some may be best to be thinner, but knocking off 2” would only save me $5.20, since the bags are all the same price. And going up from 6# density to 8# would only add $2.58 per 6” panel!

With a lot more work I could build wooden or metal frames. I figure wooden frames would bring me in at about $35 each for 6” thick. $30 for 4” thick. While these would only be open on the front, they would allow for some to be stand mounted to move around, would allow for some 6 ft or 8 ft tall/long, and would be less fragile for future moves. But is it worth the work?


From Ethan’s writings I’ve learned that for a room this small, my primary concern will be getting enough bass absorbed.

Given my desire to keep things within 8” from the wall, what is better for my application?

1. 2” air gap with a 6” thick 6# density panel
2. 4” air gap with a 4” thick 6# density panel
3. 2” air gap with a 6” thick 8# density panel
4. 4” air gap with a 4” thick 8# density panel
5. no air gap with a 8” thick 4# density panel
6. no air gap with a 8” thick 6# density panel

For corners, I assume 6” thick 8# is enough, or should I go to 8” 8#?

7’-10” tall corners will fit easily, but with special angled tops I could go to 9’. Is it worth all the extra cost and trouble?

While I know every room is different and some testing is needed to finalize my needs. What are the likely needs to get me most of the way there for good sound in this small room? This includes diffussers, etc.

I have a dB meter (Radio Shack analog), some test CDs and of course microphones. What is the easiest way to do testing? Is there cheap software to automatically do this with a microphone? (Sorry, this is one area I have not studied at all.)

What are your words of wisdom for me in this situation?


Ethan Winer 6th June 2009 08:14 PM

I'd go with #6. Thicker is always better, regardless of density. As for testing:

ETF, Windows, $150

FuzzMeasure, Mac, $150

Room EQ Wizard, Windows and Linux, Freeware

This article explains how I use ETF, but the principles apply to all such programs.

Comparison of Ten Measuring Microphones


Sugarlander 6th June 2009 09:03 PM

Thanks Ethan!

Any input from others are welcome too.

bpape 9th June 2009 04:25 AM

For 6 or 8" thick panels, you don't need the extra density. The 3lb 703 or 4lb mineral wool will be just fine.

For the 4" panels, the higher density will give you a little benefit in the bottom.

For reflection control, again, no need to spend the money on the higher density.


Sugarlander 11th June 2009 03:25 PM


Originally Posted by bpape (Post 4264052)
For 6 or 8" thick panels, you don't need the extra density. The 3lb 703 or 4lb mineral wool will be just fine.

For the 4" panels, the higher density will give you a little benefit in the bottom.

For reflection control, again, no need to spend the money on the higher density.


Thanks for the input Bryan. Your comments helped clarify this point for me.