Trap a trouble room

[bruce]

Hi Folks! I've been researching for two years and am going to plunge into treating my recording, sometimes mixing place. I use it mainly for rehearsal and recording. I,m going to use a homemade attack-wall and cloud around the mix position, as it is stuffed in an awkward corner. The important thing is to eat up sound playing live at drummers volume.

Room: 16'x16'x8'. Modes: Fundamental near 35Hz. Coincident modes shown,with bold ones triple coincident. 71,106,141,177,212,247,283,318,353.
I,m trying to send a drawing jpg. but I, can't get it to show up there, so here's a PDF.
There is a 4'x6' lightly walled off chunk of the room that forms part of a hallway with the stairwell. I have triple folded heavy curtains hanging as a door to this hall.
Floor is thin dense carpet, ceiling and walls drywall with 2 walls being exterior so they have insullation behind. Also spaced 1/2" from walls is 4' high 1/4"plywood wainscot. A full height brick gas fireplace used for heating, caps off the center of one wall. A 5'wx3'h window with heavy curtains high on back wall. Behind mix position is an 8x8x8 room. to the right of mix behind my curtain door is a deep closet under upper stairs with a wood louvre door.

I want to go with absorber types of bass trap. The plan is to make 2'x2' Tri-corner traps angled out from top of 6'6"hx2'w corner absorbers. Then custom length 1"#703 along the ceiling corners. Thinking about some half-rounds from rigid pipe insulation on the walls. I,m going to make some 6" thick moveable gobos around the insruments, so they should help some.
The untreated room leaves your head ringing. I can't do any major construction here as I rent. O.K. now comes the confusion.

In a room like this will absorber traps treat the lowest of the low?
Will the drywall and wainscot help? How much?
Can I use The 8x8 room to affect the 16x16 through the connecting door? In that matter I've got a stairwell and hallway nearly in play here.
Should I consider panel traps or some of both types?
Do panel traps mounted off wall need a thick solid back?

Tri-corners covered with a 2'x2' #703. Best thickness? Using 705 here?

I have some Roxul "Drainboard" here, that is 8.0pcf. Is there a use for this density in my room? Possibly in tri-corner absorbers?

Does anyone know if compressing (e.g.) 6"of Roxul "Safe'n'Sound"2.5pcf. between stiff wire mesh actually increases the density and performance. I'm thinking that it wouldn't need much compression to get 3.0pcf.

When people talk about "mineral wool", in absorbers and superchunks, what density do they use? Regular house insulation is only 2.0pcf at best.

If highs need reflecting off corner traps will paper posters on the trap face do anything?

Roxul also make "Curtain rock" for curtain walls. It comes in two densities; 3.5 and 4.0pcf. 2x4 panels 2"th. and up. I,m going to check price with my supplier who also distributes Owens C. in Toronto, Canada.
Glasscell Isofab (416) 241 8663.
The number for Owens customer service N. America is 1-800-328-7617, where they can give you a list of local suppliers.

[bruce]

The forum backpages that I never got to before have answered most of my questions. Thanks for the effort of maintaining this site. Mr. Winers' tests on density and Knightflys' patient and detailed responses to members' questions have cleared up my dithering.

First I'll use at least 2" #703 in the ceiling corners.
Second, doubling the thickness of rockwool in the corners.
A 12"deepx24"wide frame projects over 24" fron the corner.
To save space there I'll use 24" wide 6" bats in a frame in front, and 16" wide bats behind. I know this diminishes the distance to the wall and thus the low end effectiveness.
Any guesses as to the extra thickness (12") offsetting that effect?

Is it maybe better to use 2" Rigid Fiberglass in front of a 24" wide 6" bat, to move the back of the absorber away from the corner?

Im I correct in thinking that panel traps work better on lower frequencies?
Is it better to wait and see what the absorbers do before going to the involvement of building panel traps?
I now know that compressing mineral wool does raise the density and the performance characteristics along with it .

[Ethan Winer]

Bruce,

> Im I correct in thinking that panel traps work better on lower frequencies? <

Yes and No. Wood panel traps cam be designed to target 50 Hz and even lower, but using a lot of fiberglass gets close to that low, and the biggest problem in most rooms is from around 80 to 300 Hz.

> Is it better to wait and see what the absorbers do before going to the involvement of building panel traps? <

Yes, I think so.

--Ethan

[bruce]

Thanks Ethan for the input. I was hoping you'd say that.

I've done further research now, and I'm glancing at my screw-gun with a certain conviction. Will post again as studio comes along.