Panel absorbers question

famous beagle · Post by **famous beagle** » Sun May 08, 2005 4:50 pm

Ok guys, I've read up a lot on this site and others, and I've been told by several people that I need to put panel absorbers in several spots in my control room to help flatten out the room (first refelction points, ceiling above the mixing position, wall behind the mixing pos., and the corners, etc.).

Here's my question. Is there a site or something that explains the building of these absorbers in detail? I've gathered bits of information all over the place, but I have yet to find one place that says "this is how you do it." I realize there are different ways, but here's what I've heard so far:

1 build a frame app. 2ft x 4ft.

2 put 703 rigid fiberglass inside.

3 cover the frame with a sheet of perforated panel board.

4 cover the whole thing in fabric.

But, here's what I DON'T know and can't seem to find anywhere:

1 how do you attach the fiberglass to the frame?

2 does the panel board go on the back as well as the front?

3 if I get 1 in. 703 insulation in 2x4 sheets, how many do I use per trap?

Someone please clue me in on this; I've searched everywhere and can't seem to get these final bits of information.

Thanks

the dreamer · Post by **the dreamer** » Tue May 10, 2005 2:21 am

Hi Beagle,
It seems what you are going to build is no "Panel Absorber".
It is some kind of "Helmoltz-Resonator" which will be tuned to a specific frequency depending on percentage of perforation and depth.

If the percentage of the perforation is more than 20% (at least with steelsheet) it is almost acousticaly transparent. So this will give you a broadband trapping behaviour depending in the thickness of the mineralwool and depth of the cavity behind it. Best performance in a corner (without backpanel!)

Stop here and read before building:
http://forum.studiotips.com/viewforum.p ... 226b7354d0
http://www.johnlsayers.com/HR/index1.htm

Florian

famous beagle · Post by **famous beagle** » Tue May 10, 2005 4:45 am

Ok thanks for the tip! Someone told me along the way to use the perforated board, but they didn't mention anything about it being a Helmoltz-Resonator. I guess they were misinformed or simply neglected to give me that little piece of information.

Thanks!

knightfly · Post by **knightfly** » Sat May 14, 2005 3:04 am

Beagle, I saw your comment about not being helped on another thread; if you can re-state your questions here I'll see what I can do to help.

One thing people who are just starting out in this field tend not to realize, is that the "simple question" they asked (or 6) can't be answered simply at all, and may take more time than any of us has available at a given time.

Please remember that this is essentially a FREE site, moderated almost entirely by John and myself - we each donate somewhere in the neighborhood of 1000 or more hours a year of our time, in addition to holding down full time jobs and doing paid consultant work, etc - this amounts to what, if billed at normal rates, would be $120,000 a year (for each of us) at NO CHARGE.

I'd appreciate it if you keep that in mind when you're deciding how patient you want to be. \

I've been working on a better "FAQ" for the site that should help people help themselves, but it's nowhere near "ready for prime time" - so if you could re-state whatever questions you've not gotten answers to... Steve

famous beagle · Post by **famous beagle** » Sat May 14, 2005 8:28 am

Knightfly,

I apologize for my remark. I realize now how it came off, and I didn't intend for it to be aimed at the moderators ... or really anyone specifically. I was just getting frustrated and lost my cool for a sec. I know you and many others donate a LOT of time to this site, and I really appreciate that. I've learned lots already just from reading some of your responses in general.

I've since found the answer to the question I was looking for, but I thank you for your offer.