More Confusion Re: Absorber Panels

Posted: Thu May 08, 2008 10:03 pm

Ok. So I've got a couple of my 2' X 4' panels done and I'm ready to mount them, but confusion sets in - Ethan Winer says to mount them 4" from the wall, but when I look at pics of other control rooms on the web, I see the side and rear wall absorbers are mounted flush to the wall.

So is it 4" for bass traps and flush for broadband?

My panels are made with 2" / 6# mineralwool in 2.5" frames. I already have bass traps in the front and rear corners, as well as a 3 panel cloud ala David French on the ceiling.

Thanks.

Posted: Thu May 08, 2008 11:01 pm

I've read that 3" from the wall is a good compromise between floor space and acoustic control. And I believe this is true of the broadband absorbers, and that bass traps should have even more space behind them.

Let me know if you find out differently. I'm in the middle of building my own right now.

Posted: Thu May 08, 2008 11:12 pm

The gap behind = thickness of the absorbent material (wool). That is for wall mounted broadband absorbers.

For the corner absorbers, the wider you close the corner the better.

Posted: Fri May 09, 2008 6:00 am

Bill,

I expect Rod (et al) will correct me if I'm wrong, but essentially your understanding is correct... e.g.;

A narrower gap between the absorber and the wall decreases the frequency range of absorbtion in regards to the lowest frequencies absorbed.

As most rooms (assuming your mix environment) cannot have enough bass trapping, I would suggest that a 3"-4" gap would help more than a flush mount.

HOWEVER... Before just accepting random advice, I would ask you this; Have you done any testing to confirm if you have any specific needs for a particular frequency or frequencies to be dealt with?

If you have not already done one, I would suggest doing at least a waterfall and RT60. Post the results here, at John Sayers or Studio Tips

Don't get me wrong. You are probably just fine to go ahead. But, wouldn't you hate to go through all this trouble, only to find out you needed to hang the absorbers another inch further out AND needed to maybe build a set of Hemholtz Resonators?

An informed decision based on some scientific data is far more comforting, in my humble opinion, than a stab in the dark... not to mention the value of your work that you've obviously already done.

Posted: Fri May 09, 2008 10:53 am

"An informed decision based on some scientific data is far more comforting"
The Christian in me is screaming at that statement, but that's another point altogether.

I totally agree though, get some hard fast evidence before you drop cash on anything, especially something which would leave your mix room in tatters.

Posted: Fri May 09, 2008 3:58 pm

Thanks guys for all your genuine concerns.

I've already dropped a little bit of cash for mineralwool, burlap, wood for frames. My question wasn't whether or not I should take measurements of my room, that's a given (just waiting on my tax rebate to buy a good quality, fairly flat response omnidirectional mike).

I'm doing the standard bass trapping and broadband absorbtion recommended for very small rooms (15' X 10').

I was just curious why one bass trap company insists that a 4" air gap be used, while numerous pictures of control rooms on the web (some on competitors websites) show panels at the 1st and 2nd reflection points mounted flush to the wall. Now I understand that the gap can include the empty space of the frame not filled with material; i.e. 2" mineralwool in a 4" frame = 2" gap.

BTW, the improvement in clarity and stereo imaging from just the little I've done so far is AMAZING!

I'm looking at a matched pair of Shure KSM14's for drum overheads that might be useful in the omni configuration for room analysis. It's frequency response curve is fairly flat in the omni mode. Not quite as flat as the KSM44, but I need new overheads badly anyway. One guy told me I could get a dbx mic that goes with the Driverack units, for around $100USD. Anyone with experience with that mic that would know how flat it is?

Codemonky wrote:

Quote:

"An informed decision based on some scientific data is far more comforting"
The Christian in me is screaming at that statement, but that's another point altogether.

Yeah, I sometimes rely too much on my own intelect and that of others instead of just asking and trusting He'll give me the right answer.

Posted: Fri May 09, 2008 6:54 pm

AwedOne wrote:

So is it 4" for bass traps and flush for broadband?

Like to see an untreated corner area under the influence of sound in zero gravity? Sure ya do!

http://www.adl.gatech.edu/research/tff/ph1final_acoustic.html

It's not the zero gravity so much that matters in relation to bass trapping. It is what sound can do when it gets in those areas. No more speculating, you can build a wall from sound!

I am practically beside myself even now and this was ten years ago!

Posted: Fri May 09, 2008 7:25 pm

Umm...yeah....ok,

but does the kick sound really tight? Confused

Posted: Sat May 10, 2008 8:38 pm

AwedOne wrote:

Quote:

"An informed decision based on some scientific data is far more comforting"
The Christian in me is screaming at that statement, but that's another point altogether.

Yeah, I sometimes rely too much on my own intelect and that of others instead of just asking and trusting He'll give me the right answer.

The atheist in me is confused by that statement. Are you suggesting we should pray for divine guidance on the subject of bass trapping?

Posted: Sun May 11, 2008 8:24 am

And where does this leave the agnostic?

Posted: Sun May 11, 2008 9:25 am

"instead of just asking and trusting He'll give me the right answer."
IMO He gives pretty good answers via everyone on this forum.

"Are you suggesting we should pray for divine guidance on the subject of bass trapping?"
You could...wouldn't do any harm I would think.

"And where does this leave the agnostic?"
In a scientifically designed room.

Posted: Sun May 11, 2008 10:46 am

Codemonkey wrote:

"instead of just asking and trusting He'll give me the right answer."
IMO He gives pretty good answers via everyone on this forum.

No, that's people answering you, not god.

Its quite important to be able to tell the difference...

Posted: Sun May 11, 2008 11:07 am

OK, I'm getting wrapped up in theology again. I'll just go sit in a corner and mutter things.

Posted: Sun May 11, 2008 11:10 am

Codemonkey wrote:

"And where does this leave the agnostic?"
In a scientifically designed room.

Nice.

Posted: Sun May 11, 2008 11:21 am

Right. I may burn in hell or collect the gold promised me or simply turn back into dirt...but I'm gonna sound good either way !

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