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Testing a panel design
Old 2nd September 2011
  #1
Testing a panel design

I'd like to test a few panel designs before committing to a full scale treatment overhaul in my control rooms. I'm looking to build both bass traps and diffusers. I would really like to test for a simple before/after result and hoped that I could use my VO booth (14'x11'x8.5') for testing. The plan is to do a baseline measurement with REW and use that to generate a CAL file. The speaker and mic would be in a fixed position. I would then test each panel design, which would be sized to cover the studio window(highly reflective), and using the CAL file, see any change as simply + or - from the CAL plot.
Would this work at all, or am I dreaming? I know it's no substitute for true acoustic lab testing, but if it could at least rule out some completely useless ideas, it would be handy.
Old 2nd September 2011
  #2
Old 2nd September 2011
  #3
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avare's Avatar
 

Quote:
Originally Posted by Jens Eklund View Post
A great article. Thanks!

Andre
Old 2nd September 2011
  #4
Ahhh, nothing like a little light reading...
Hopefully, I can get my head around this. Thanks for the link.
Is there a consensus as to which test is most often used for, lets' say, bass trap testing? Is it that a specific material would be tested in the 'tube' type testers, and a complete panel(s) would be in the reverberant room?
Old 2nd September 2011
  #5
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Jens Eklund's Avatar
Quote:
Originally Posted by [email protected] View Post
Ahhh, nothing like a little light reading...
Hopefully, I can get my head around this. Thanks for the link.
Is there a consensus as to which test is most often used for, lets' say, bass trap testing? Is it that a specific material would be tested in the 'tube' type testers, and a complete panel(s) would be in the reverberant room?
Regarding the reverberation room method:
https://www.gearslutz.com/board/6993300-post51.html
Old 2nd September 2011
  #6
Got it. (I'll go away and do some reading)
Old 4th September 2011
  #7
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A practical example... by Jens, not really a bass trap, but it is example of calculation of absorption coeff. using measurement of reverberation time before and after bass traps is installed, in an empty and resonant room.
https://www.gearslutz.com/board/6493935-post13.html
Old 5th September 2011
  #8
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Quote:
Originally Posted by boggy View Post
A practical example... by Jens, not really a bass trap, but it is example of calculation of absorption coeff. using measurement of reverberation time before and after bass traps is installed, in an empty and resonant room.
https://www.gearslutz.com/board/6493935-post13.html
Well, not really sited for "bass trap" -testing due to the reasons linked to above. Values below approx. 300-400 Hz are not very accurate due to the lack of a diffused field in such small room at low frequencies. Perhaps if used as a "standing wave facility" and not a “reverberation room”, it could be used for low frequency absorption measurements.
Old 5th September 2011
  #9
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Quote:
Originally Posted by Jens Eklund View Post
Well, not really sited for "bass trap" -testing due to the reasons linked to above. Values below approx. 300-400 Hz are not very accurate due to the lack of a diffused field in such small room at low frequencies. Perhaps if used as a "standing wave facility" and not a “reverberation room”, it could be used for low frequency absorption measurements.
I think that it is not needed to be too much accurate...
He needs some way for testing his traps, and your example is great. Nothing can be ideal and I believe that he is aware of this.
Analyzing room modes before and after acoustic treatment in some target room will reveal efficiency of bass traps for sure, with or without enough diffuse field inside, because we don't always need to calculate a precise absorption coefficients, but only efficiency of treatment (at least we need absorption coefficients to predict efficiency of absorption treatment). I believe too that he has no plans to sell his traps to other people.
Old 6th September 2011
  #10
Agreed, I'm just looking for a simple procedure that can tell me if a bass trap covering, for example, is helping some way or not worth the trouble or worse, cancelling out some of the low freq absorption. My VO booth is about 1/6 volume of my main control room, so I was thinking that I could try different ideas and then scale up the treatment for the main room.
I don't have any plans to sell the designs, but if that were to ever change, I would of course seek proper testing.
Thanks for all responses, guys!
Old 6th September 2011
  #11
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Quote:
Originally Posted by [email protected] View Post
Agreed, I'm just looking for a simple procedure that can tell me if a bass trap covering, for example, is helping some way or not worth the trouble or worse, cancelling out some of the low freq absorption. My VO booth is about 1/6 volume of my main control room, so I was thinking that I could try different ideas and then scale up the treatment for the main room........
There is a different way to get very illustrative information (IMHO) about efficiency of absorbers in same room, using "Burst Decay" analysis from ARTA software for acoustical measurements, in "Sonogram" mode, directly, without calculating absorption coefficients, but displaying time of duration of room modes.
It's a same software that you may use for calculation of RT60, this is only a different analysis of same measured impulse response.

Some examples:

Before and after:
https://www.gearslutz.com/board/67908****post34.html
(there are links to many more examples of measurement of absorber's efficiency)

And one of my results (only after treatment):
https://www.gearslutz.com/board/6791029-post38.html
https://www.gearslutz.com/board/6791239-post43.html

Good luck!
Old 6th September 2011
  #12
Thanks, Boggy!
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