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Soffit style traps. 12" cube in 4lb enough to help my 60hz issue?
Old 25th September 2012
  #1
Soffit style traps. 12" cube in 4lb enough to help my 60hz issue?

Still have a few room modes, and am going to add soffit traps to the bottom corner of my room. Wondering if 12" is enough or if i should do an 18" cube? 18" seriously starts to sacrifice room space.

Thanks,
Jeremy
Old 25th September 2012
  #2
Gear Guru
 
Glenn Kuras's Avatar
 
🎧 15 years
You really want to go with 17" or more... I am sure if you covered ever corner area with 12" it would have "some" effect on 60hz but I doubt enough.
Old 25th September 2012
  #3
I'm correct to assume that 4lb is ideal for this type of trap?
Old 25th September 2012
  #4
Also, does it matter if they are symmetrical? Eg- 12" traps in the back of the room, and 18" traps on the front wall. Not sure i can sacrifice 18" in the back of the room.
Old 25th September 2012
  #5
Lives for gear
 
avare's Avatar
 
🎧 15 years
I am somewhat confused. Why did you write cube in the title? There is no acoustic advantage to a cube over a triangular fill. For 12" across the face Safe N Sound type material is the best acoustically. Same for 17" across the face. The nice thing is that it is cheaper than 4 lb/ftΒ³ material too!

Andre
Old 25th September 2012 | Show parent
  #6
Lives for gear
 
🎧 5 years
Quote:
Originally Posted by jeremycox ➑️
Also, does it matter if they are symmetrical? Eg- 12" traps in the back of the room, and 18" traps on the front wall. Not sure i can sacrifice 18" in the back of the room.
Symmetry is left/right for most monitoring purposes, so having different traps front/back shouldn't be an issue.

Also, like Andre said, 4pcf isn't the right material. If Safe n Sound is less dense, use it.
Old 25th September 2012
  #7
Soffit style traps.  12" cube in 4lb enough to help my 60hz issue?-screen-shot-2012-09-25-5.43.10-pm.png

I was making traps like this. Had a few extra bundles of 4lb, and assembled the traps using corner bead and 3/16th rivets. The rivets fit into the holes in the corner bead so it only took about 10 minutes to assemble the traps.

They unfortunately dont seem to help much though.


here is a little grab of before and after adding 2 traps to the floor in the front of the room. Its a few db better (mode actually at 77 not 60 as previously stated) but nothing spectacular. These increments are 5db and the smoothing it 1/24th

These bass modes are driving me crazy. I have 6" traps in all of my vertical corners, 2 tuned 6" gik traps on the back wall, 5 4" traps and 3 2" traps around my room.
Soffit style traps.  12" cube in 4lb enough to help my 60hz issue?-screen-shot-2012-09-25-5.42.06-pm.png
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Old 25th September 2012
  #8
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gullfo's Avatar
 
🎧 10 years
do you have the mdat file from your room measurement?
Old 26th September 2012
  #10
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gullfo's Avatar
 
🎧 10 years
looking at the levels, you probably need to redo these measurements after calibrating because you're showing 120-140db
Old 26th September 2012
  #11
yeah everytime i calibrate my setup i get very skewed responses. REW wont even work with my lynx aurora for some reason, i have to use my old duet. REW seems really buggy on my mac....
Old 26th September 2012
  #12
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gullfo's Avatar
 
🎧 10 years
check your drivers on the mac
Old 27th September 2012
  #13
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3 Reviews written
🎧 10 years
I've seen people suggest using the mic input on a Mac for REW. Are there other options that work well?
Old 27th September 2012
  #14
Gear Nut
 
🎧 10 years
Actually it's Java for Mac that is having problems with firewire interfaces.
Not REWs fault ...
Old 27th September 2012
  #15
I was able to get it to work using an apogee duet, but its very buggy. Seems like you have to calibrate SPL meter, calibrate sound card, and calibrate SPL meter again every time you open the program. Then randomly the scale would change and i would have to calibrate the SPL meter again....
Old 28th September 2012
  #16
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JLiRD808's Avatar
 
2 Reviews written
🎧 10 years
Hope u dont mind me chiming in...I have a 63hz dip Im trying to address.

Jeremy, based on that graph, are u also concerned with the 75-95hz dip or are u dealing with that in a totally different way?

Also, is Safe n' Sound the best material to go with when dealing this low? I have a stack of 705 at around 4.8lb/cu ft. Im thinking its NOT IDEAL either. How about R30 or some other pink fluffy?

Jeremy, do u know how to detect where the bass is building up in ur room using an SPL meter and some low freq sweeps or pink wave? Been doing this a lot lately...really narrowed down WHERE I should put traps instead of just throwing them in EVERY corner and then measuring.
Old 28th September 2012 | Show parent
  #17
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GIK Acoustics's Avatar
 
🎧 5 years
Quote:
Originally Posted by JLiRD808 ➑️
Also, is Safe n' Sound the best material to go with when dealing this low? I have a stack of 705 at around 4.8lb/cu ft. Im thinking its NOT IDEAL either. How about R30 or some other pink fluffy?
The GFR for Safe n Sound is around 8,000, where pink fluffy is around 5,000. In comparison, OC705 is said to be around 30,000. Safe n Sound for large absorbers works quite well, and up to at least 12" (the largest I've looked on a calculator) outperforms pink fluffy slightly.

Quote:
Originally Posted by JLiRD808 ➑️
Jeremy, do u know how to detect where the bass is building up in ur room using an SPL meter and some low freq sweeps or pink wave? Been doing this a lot lately...really narrowed down WHERE I should put traps instead of just throwing them in EVERY corner and then measuring.
Jeremy, this is the method he is referring to: http://www.gikacoustics.com/video_te...placement.html
Old 28th September 2012
  #18
Thanks for the replies.

Im considering using this 4lb i have in some limp mass absorbers. My RT60 times are still over half a second under 100hz, so i still clearly need some bass absorption.
Old 28th September 2012 | Show parent
  #19
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by JLiRD808 ➑️
do u know how to detect where the bass is building up in ur room using an SPL meter and some low freq sweeps or pink wave? Been doing this a lot lately...really narrowed down WHERE I should put traps instead of just throwing them in EVERY corner and then measuring.

an SPL meter or your ears are related to pressure, but porous absorbers are velocity-based (need to be placed at areas of high particle velocity for a given wavelength; with pressure and velocity being inversely proportional).
Old 28th September 2012 | Show parent
  #20
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JLiRD808's Avatar
 
2 Reviews written
🎧 10 years
Quote:
Originally Posted by localhost127 ➑️
an SPL meter or your ears are related to pressure, but porous absorbers are velocity-based (need to be placed at areas of high particle velocity for a given wavelength; with pressure and velocity being inversely proportional).
Hmmm...could u explain that further? I understand the difference between pressure and velocity, but then how do u find where the velocity is high?

Also not sure what "pressure and velocity being inversely proportional" means in layman's terms. Does it mean that where there's pressure, there's no velocity, and where there's no pressure, there is significant velocity?

THANKS!
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