[Nils]

I've been playing around with my setup, and right now I have all 8 of my GIK D1 panels off the wall.  Before I put them back, I'd like to somehow add mass to them by filling up the cavity behind the plastic shell.  I figure extra rigity never hurts.

Is there an expanding foam or lightweight cement mix that's conducive to small-scale applications?  There's no easy way to seal off the rear cavity, so something that could fill it in and then set solid would be really ideal.

Thanks,
Nils

[woodsyi]

How big a cavity?  Will this do?
http://www.dap.com/product_details.aspx?product_id=11
or this?
http://www.dap.com/product_details.aspx?product_id=416

[bpape]

There are 2 ways to approach it.  You can add mass simply by adding Mortite (rope caulk) to the inner surfaces.

Or, if you want a bit of additional midbass control, you can fill with fiberglass insulation.

Bryan

[Nils]

Thanks Bryan.  My main concern with fiberglass or acoustic cotton is having it stay in the diffusor cavity.  It'd stay in once it was against the wall, but I'd prefer a cleaner solution.

[bpape]

Your call.  A dab of spray adhesive would keep it in place easily.  Just offering options as to how you want the filler to react with the cavity.

Bryan

[Big Red Machine]

Like this: 

[Glenn K]

Like this: 

What are you feeding your dog?

Glenn

[Nils]

I've been slacking off on my listening room... I decided to try RAAMmat, which is a contrained layer device, instead of buying 20 boxes of rope caulk.  I heard this stuff works wonders for killing resonance (you can feel the D1 panels vibrate sympathetically quite a bit when the volume is anything more than quiet.  Then again, they are 4.5' from the speakers...

Will report on findings later.

http://www.raamaudio.com/cgi-bin/index.cgi?p=pr
-- Nils

[ooheadsoo]

Hey Nils, if you have extra and don't live too far, I MIGHT be interested in taking some off your hands.  I just bought 4 panels.

[Nils]

I live in Santa Cruz, CA... I'll keep you posted.

[Big Red Machine]

The large diffusors at RMAF were filled with a plaster-like substance for real mass.



http://www.audioxsell.com/community/events/7/1400/Rocky-Mountain-Audio-Fest-2007/Einstein-Audio.htm

[Nils]

I was thinking about plaster or cement, but I think a few layers of constained layer damping material will work quite well

Also, those Golden Acoustics panels are nuts.  Yay Golden Ratio?  I dunno.  I wonder how well they work.

-- Nils

[ooheadsoo]

I live in Santa Cruz, CA... I'll keep you posted.

Cool!  I'm down in LA.

[laserman]

Here is another product lead to check out.  I know some car guys who swear by these products from Elemental Designs.  They say the support there is great too.  If you want to cut some small pieces of OC703 and stick it to this product, I think it will work and stay there a long time.  However, I would call them to make sure.   

LINK

[satfrat]

I'm wondering how an open cell memory foam would work in this application? Open cell memory foam is good stuff for vibration obsorption but I'm not sure if that's a desirable trait for diffusion panels? Just asking questions and not supplying answers here,,, just so we're clear. 

Robin

[bpape]

It all depends on if you want to damp the shell and forget getting any bass absorbtion benefits from the cavity - or concentrate on getting the bottom end control.  2 very different ways to approach it.  Personally, I'd go for something like fiberglass or cotton that will absorb and provide additional bottom end decay time control.

Bryan

[satfrat]

Well that's why I asked cuz the man seems to want to dampen or stiffen up the plastic cavity's when I'm wondering if that's what he really shouldn't be wanting to do. Stiffing or reenforcing the plastic would result in more reflection when I'm thinking diffusing is another way of saying slowly obsorbing energy in which case fiberglass would do just that,,,, or just leaving them empty. As I said earlier, no answers here, I'm just thinking outloud. Thanks Brian. 


Robin

[bpape]

Well, diffusion is really reduction of energy by scattering in a physical dimension and also in time.  You're really not absorbing per se - but there are cancellations in the wells that cancels through destructive interference.

In his particular case with Maggies, maybe a stiffer surface would be a preferable solution.  In most other applications, I'd go for the absorbant filling to get the bottom end control.

Bryan

[Nils]

For the record, I have 4 GIK tri-traps, 2 GIK monster bass traps, 4 ASC StudioTraps, and 2 minitrap HFs (spaced 3" off the rear wall).  My low end is very well taken care of

Still haven't gotten around to RAAMmat'ing the D1 panels--I've been caught up a bit in working on my mini-HT room (old speakers + 50" TV!)

-- Nils