Control Rool: Foam or mineral wool

[Helge K.]

Hi there,

I'm just about finishing my basement studio. For the control room, I'd like to mount panels to avoid direct reflections.

From Ethan's great website I understood some prefer mineral wool mats. Here in Europe, wave oder pyramid shaped foam is what seems to be used most, for some reason.

What worries me about the mineral wool products is the glass parts in it that might come out of the fabric around. I still have some foam left from my previous basement studio, that I might use again (see photos). My idea was to fix it to the walls with a wooden frame with a thin flexible plywood back, to have an effect on even lower frequencies.

So my questions are, what material would use use, where would you place panels, and what size would you recommend for the panels?

Feel free to have a look at both, my new control and recording room, to have a better understanding of my situation:

http://de.photos.yahoo.com/gitarren_mann

Thanks,

Helge

 

[Ethan Winer]

Helge,

The main difference between foam and rigid fiberglass is that fiberglass is more effective at lower frequencies. But if you already have foam, by all means try that first.

> My idea was to fix it to the walls with a wooden frame with a thin flexible plywood back, to have an effect on even lower frequencies. <

No, the plywood will negate any advantage of an air gap. When using foam or fiberglass, it's always better to mount them away from the wall leaving only an air space.

--Ethan

 

[RICK FITZPATRICK]

Ethan, I have a question about the plywood. In an old studio design book I have, the author details a formula for a "bass trap", which has been used for decades. I beleive it is just a wood frame, mounted to a wall and sealed, and a sheet of plywood fastened and sealed on the face. I beleive the depth, length, width, and panel thickness determine the range of frequencies that are affected. This is a panal absorber, correct? Please clarify if not.
They also described lining the box with 703(book said rigid fibreglass. For dampening I assume.) Now, it goes on to say, you can then fasten another frame or 2x2 strips to the perimeter face, and place another layer of 703, spaced off of the plywood face about 1/2", and then cover with fabric.
I haven't had a chance to visit your site lately, so I have not had the opportunity to see your manufactured panels, but it seems that this is the same thing, or similar. And you have mentioned that using 705(foil face?)used with the foil face in, can lower the absorpsion frequency. Am I understanding this correctly?
Now for slot absorbers(slats). This is a hemholz resonator, is that correct? And it is a box also with a series of slots, which act as the neck of bottles(box) whereby the slot depth and width(and length?), AND the box depth, width, and length also determine the absorption frequency characteristics. Am I understanding this correctly?
If so, it would seem to me, that given the fact that these are all box's, even open studwork filled with fiberglass and sealed sheetrock on the rear face of walls(ie, SAE) and then covered with slats, can be built in a MULTITUDE of configurations and layers if done correctly. That tells me, adjacent rooms, closets, cabinets, junk boxes and anything that can be construed as a box, can be modified, altered, and manipulated till it meets said resonator criteria.
As an example. IF, a room or space adjacent to a controlroom, like a closet, can partially or fully act as a hemholz resonator box, or panal absorber box, then the only requirement is the following:
In the case of a panel absorber, the divider between the two spaces(wall) would become the panel. AS IF you had a double door opening between the two spaces and you closed it off with a sealed panel and the interior of the box(space) was completely sealed off from the control room. Like a double closet whereby you replace the doors with a panel. OR, approprietly sized slats and slots to become a slot resonator.
Does this sound preposterous? I am trying to understand the implications of this box equals resonance absorption principle, and look at things from another angle, to utilize non linear thinking in my design approach for space allocation.(what did he say?) Maybe attic space? Why not use attic space as a slot resonator box, as long as the roof isn't the only line of defence for ceiling soundproofing. Would that not imply that a ceiling of a room within a room design becomes the soundproof barrier, and a sub-ceiling below it could become the face of a slot resonator? Or panel absorber.
My Everest book is packed away, so I don't have a way of looking up these formula's
at the moment. Probably wouldn't do anygood if I could. Sooooooo.....
Please give me a reason why my understanding is idiotic, so I won't burn any more brain cells on rediculous conceptual design that is based on nonsence.
And knightfly, if you say one more time that guesswork is my forte', I'll drive right over to your house and k.........how tall did you say you are? (I've been known to be foolish in the past)
fitZ
(like I've said before, gotta have some fun here once in a while!

 

[Ethan Winer]

Rick,

> This is a panal absorber, correct? <

Yes, and complete instructions for building those is in my Bass Trap Plans article. See my Acoustics FAQ, 10th in the list here:

www.ethanwiner.com/articles.html

Besides having a link to my trap plans (near the very top), it explains many other acoustic issues in detail too.

> I haven't had a chance to visit your site lately ... <

My company's site www.realtraps.com does have panel traps, but we now sell a new product called MiniTraps that are much less expensive and just as good if not better than panel traps. Rather than wood they use fiberglass and two types of membrane materials, so they trap bass and also absorb mid and high frequencies.

> Now for slot absorbers(slats). This is a hemholz resonator, is that correct? <

I believe so, but I'm not an expert with slat absorbers. Some of the other guys here like Steve and Thomas can advise you about those.

> given the fact that these are all box's, even open studwork filled with fiberglass and sealed sheetrock <

Yes, there are all kinds of ways to build panel traps and other bass traps right into the walls.

--Ethan

 

[RICK FITZPATRICK]

Thanks Ethan. I just moved and have been offline for 3 months. I now have a whole new set of acoustic and soundproofing demons to solve. Your info helps.
fitZ