8lb mineral wool for treating small control room

[eric w.]

This forum has been a tremendous help to me in trying to figure out how to treat my small control room. I have a plan, found a supplier, and will order in the next few days. My plan is as follows, and if it sounds out of whack to anyone please let me know. Home studio, low budget, etc..

The room is quite small, and my plan is to work with absorption first.

My local supplier doesn't carry OC703/705 but they do carry Roxul RHT80 (2" thick 8lb density w/ spec sheet attached). It comes in cases of 6 each 2' x 4' panels for $42/case.

Rectangular room dimensions are 9'-4" wide x 11'-8" deep x 6'-6" ceiling height. The room is currently carpeted.

I am planning on full height 2' wide x 4" thick panels to straddle each corner. Two 2' x 4' x 2" thick panels on the side walls for early reflections. One 2' x 4' x 6" thick bass panel at the rear of the room. and a 6' x 4' x 4" thick suspended cloud above.

Requires 27 each 2' x 4' x 2" thick panels - 5 cases @ $42/case + $30 delivery charge
$240.00. Have access to wood for frames, would then just need to purchase fabric. Seems like a good price.

Good plan? Much appreciated!

[PaulP]

Originally Posted by eric w.

This forum has been a tremendous help to me in trying to figure out how to treat my small control room. I have a plan, found a supplier, and will order in the next few days. My plan is as follows, and if it sounds out of whack to anyone please let me know. Home studio, low budget, etc..

Welcome.

Looks like a good start to me. If you're prepared to spend some time (perhaps
quite a bit) to get the best sounding room possible I suggest you get yourself
a copy of the free Room EQ Wizard testing software. This will let you see
how your room is now, and then what happens to it as you add treatment.
You'll know what you're doing and where you're going. You'll also need an omni
condenser microphone or a Radio Shack SPL meter.

If on the other hand you just want a better room than you have now and are
more interested in getting on with mixing, playing music or whatever you plan
to do in it then you'll probably be ok.

If you have some spare time read as much of this forum and the other one
Studio construction & acoustics. There are lots of people in the same situation
as you.

Paul P

[ciro]

Good plan.
Software will helps with details like monitors/engineer position (it matters a lot).

I´d personally go with a wider trap on the rear wall (two 2'x4' x 6" panels for a room that size will be fine).
Absorption in the front wall is a good idea
Good luck!

Ciro

[eric w.]

Thank you both for your comments and suggestions. They are much appreciated.

I decided to go ahead and also make a few panels for the adjacent room where I do my recording (as well as an additional trap on the rear wall of the control room as suggested). My total panel count is: 5 ea 2'x7'x4" thick corner traps, 2 ea 6'x4'x4" thick ceiling panels, 4 ea 2'x4'x2" thick wall panels and 4 ea 2'x4'x6" bass traps on stands.

Started construction today. I'm using 1/2 maple plywood for the frames and giving the edges a bullnose on the the outside. I found a light brown felt that I like to cover the face of the mineral wool. It was $5 a yard for a 72" roll. I figured I need about 20 yards, so about another hundred bucks. The plywood was maybe about $200 worth. Also, I ended up with 7 cases in total of the mineral wool. That's about $650 so far.

I have a tube mic with an omni pattern that I'll take some measurements with before I install the panels. I'm excited to see the results!

In the meantime, here are a few pictures of my progress. I have all the wood cut for the frames and assembled a single panel to make sure my design is okay. Also got started on assembling a few more frames. Lots of work left!!

[Glenn Kuras]

Looking good so far. thumbsup

[Lonely Raven]

Those are some nice lookin' frames!

[Weasel9992]

8lbs is pretty dense to treat a whole small room with...I'd stick with something less dense than that for the most part...like 6lbs or 4lbs...then use the 8lbs for the back wall and back corners.

Frank

[eric w.]

Originally Posted by Weasel9992

8lbs is pretty dense to treat a whole small room with...I'd stick with something less dense than that for the most part...like 6lbs or 4lbs...then use the 8lbs for the back wall and back corners.

Frank

Thank you for your input. Unfortunately I've already received the material and it's non-returnable. My supplier did not have any 6lb or 4lb density material available. In any event, I'll post my measurements of the room as-is and after installing the treatment.

Question: Taking this suggestion into consideration, does anyone think I should use 2" instead of 4" for the corner traps in the front of the room or 2" instead of 4" for the ceiling?

All input is welcome and very much appreciated!!

[ciro]

Originally Posted by eric w.

.
Question: Taking this suggestion into consideration, does anyone think I should use 2" instead of 4" for the corner traps in the front of the room or 2" instead of 4" for the ceiling?

All input is welcome and very much appreciated!!

My room has the same dimensions (altough my ceiling is around 9')
My experience is that treating the front portion of room (ceiling and front corners,ex.) with thicker absorption will give you the best results - flatter response and short decay times in the lows.

4" is a minimun.6" is better.Don´t use only 2" in the corners.

*My ceiling cloud is a 7" panel (3lb density) + a superchunk type (2lb density) in the front wall/ceiling corner (two 2'X4' panels)
*My front wall/wall corner traps are 4" (4lb) + superchunks (2lb) behind it.

Ciro

[Weasel9992]

4" is the minimum for bass trapping.

Frank

[Lonely Raven]

Originally Posted by Weasel9992

4" is the minimum for bass trapping.

Frank

But doesn't having 8pcf stacked 4"+ deep start to impede the absorption due to it's density?

I keep hearing mixed information on this. And of course this is after I make some 8" thick 8PCF absorbers.

[Brainchild]

Looking through old acoustic info files, I ran across this little snippet just before reading through this thread:

[from page 485 of _Sound Reproduction: Loudspeakers and Rooms_ by Floyd E. Toole]
"In recent discussions with Dr. Peter D'Antonio, he said the following:
'For optimal absorption, a porous absorber should offer a surface
impedance with a low-flow resistivity, which matches that of air
to remove reflections, while offering a high internal acoustic
attentuation. When attempting to control reflections with a single
density material, it is fair to say that thin fiberglass panels
should not be used, and in my view lower density is preferred over
higher density. In addition, thicker panels and a rear air cavity
both contribute to extending the absorption to lower frequencies.'"

and

"When it comes to sound absorption, it could be useful to ask what is used in anechoic chambers, where the goal is complete elimination of sound above a certain 'cut-off' frequency. In traditional designs, the wedge-shaped absorbers must be at least 1/4-wavelength long at the lowest frequency of interest...The material used in these wedges is usually compressed glass fiber with a density of about 3 pcf (48 kg/m3). According to one study, that density appears to have been a choice of convenience (structural rigidity and particle shedding considerations) because a lower-density material (1.1 pcf, 18 kg/m3) was closer to the acoustical target performance." [Koidan et al., 1972].

[Lonely Raven]

That's about what I was thinking as well. I saw a great deal on 8 pcf just after Glen mentioned using 8pcf for bass traps, and I think I over did it on the build.

I might have to open them up and adjust some.

[Glenn Kuras]

Originally Posted by Lonely Raven

That's about what I was thinking as well. I saw a great deal on 8 pcf just after Glen mentioned using 8pcf for bass traps, and I think I over did it on the build.

I might have to open them up and adjust some.

Right 8 pound is fine. I think Frank was talking about expense. Meaning you can use 4 pound and up which will save you money. But 8 pound will work a bit better for the low end

[eric w.]

Originally Posted by Glenn Kuras

Right 8 pound is fine. I think Frank was talking about expense. Meaning you can use 4 pound and up which will save you money. But 8 pound will work a bit better for the low end

Awesome. Thanks so much, Glenn!

Finished building the frames yesterday, today will be sanding and (hopefully) the first coats of finish.

[oscar gamble]

Looks good.

Please keep us posted. I'm battling a ceiling problem right now and I'm sitting on a whole batch of unused mineral wool I had initially used in my ceiling joists. I want to see how your work with the mineral wool traps go.

[Saddle]

Originally Posted by Weasel9992

4" is the minimum for bass trapping.

Frank

What about 2" (6pcf) with a 1" air space behind it? I under stand that having an airspace greatly enhances the effectiveness of the trap.

[avare]

Originally Posted by Saddle

What about 2" (6pcf) with a 1" air space behind it? I under stand that having an airspace greatly enhances the effectiveness of the trap.

No.

Andre

[tINY]

My understanding is that the air space behind the wall only allows you to put a bit less material up. The distance from the outer surface to the wall is the more important part for low frequency effectiveness.

I would expect that 2" with 1" gap would be noticeably worse than 4" with no gap.

2"with 2" gap won't be as good as 4" with no gap, but might be close at lower frequencies.



-tINY

[avare]

Originally Posted by tINY

My understanding is that the air space behind the wall only allows you to put a bit less material up. The distance from the outer surface to the wall is the more important part for low frequency effectiveness.

I would expect that 2" with 1" gap would be noticeably worse than 4" with no gap.

2"with 2" gap won't be as good as 4" with no gap, but might be close at lower frequencies.

Correct.

Andre