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Question about bass trapping corners
Old 13th May 2009
  #1
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Question about bass trapping corners

I'm in a 10ft X 10ft X 8ft room. My band practices here and and soon we'll be doing some recording/mixing. There are 10 2" 3lb Knauff panels being delivered. Is it necessary to go floor to ceiling for corner trapping? How do I know how much bass issue I have? If I'm just trying to make it easier for us to hear ourselves(cancelling the slapback, false echos, etc) is low freq bass trapping the biggest priority? Walls are sheetrock, floor is mid grade carpet, a perfect example of typical new construction Cali apartment living.
How best to make use of my material? I'm thinking doing the whole ceiling in 2 in panels, and then alternating 2 in then 4 in around the room.

Suggestions? Hints? Thanks to all. And especially to Ethan and Glenn.

Mckinetic
Old 13th May 2009
  #2
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You are referencing a few different problems here - modal issues, slap echo, RT60

For the bass traps in the corners, floor and ceiling corners are technically the best, as they are the intersection of 3 walls. Typically, you can't have too much bass trapping (unless of course you end up over-damping the mids and highs)

You can shoot the room with a freeware program like Room EQ Wizard to get an idea of what is going on. (or just walk around the room and make noise/listen)

Finally - I wouldn't cover the whole ceiling and most of the walls with traps, especially without shooting the room first. You want a room with controlled acoustics, not an anechoic chamber.

...battery on laptop dying! more later...
Old 13th May 2009
  #3
JWL
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Your room is very nearly a cube, so it will need even more bass trapping than most rooms. The rockwool you have coming is a start, but you'll need more than that.

If that were my room, I'd start by using 4" thick panels across all corners, including wall/ceiling corners.

Then I'd put absorption above the drum kit, the singer, and perhaps above the guitar amps.

After these 2 steps you'll probably be done, such that "done" equals very happy with how much better it sounds. If not, spot treat the walls wherever needed.
Old 13th May 2009
  #4
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Re

Ok thank you for your replies. After using the program, it appears I'm heavily saturated in the high department, at least that is what I took from the graph. At 50 HZ the lines were single, about 2k and up they get all doubled and much darker. So this means? Am I interpreting these results to mean I need less corner bass trapping? And a total newb question...these results change if I change the speaker setup?

Thanks again.

Mck
Old 13th May 2009
  #5
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Nope - your graph does not mean that. (But if you could post it here, we could take a look at it)

Remember, from 50 Hz - 100 Hz (one octave) there are fifty values to represent. From 2000 Hz - 4000 Hz (also one octave) there are 2000 values to represent.

And yes - speaker placement makes a big difference.
You are in a (almost) cube, which will make modal problems very significant. However, I'd still start by putting your listening position 38% down the longest axis of your room.
Old 13th May 2009
  #6
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Re

Thank you for helping me in my ignorance. This is the file. I cannot place my listening position too much different than right now as we also use this to practice in. Might could move it a bit, not much. I have now order some Knauff with the FRK backing. Is this correct? Makes for good bass absorption, yes?

Thanks again. Hopefully the file uploading process worked well.

Mck
Old 13th May 2009
  #7
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^^(can't see the file)
Old 13th May 2009
  #8
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Measurement pics.

Here they are with my apologies.

Mck
Attached Thumbnails
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Old 13th May 2009
  #9
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Okay, here's the thing...the plots only show us what you might expect from any 10x10x8 room. The only er room dimension is 8x8x8. Plus, it's a practice room, right? I wouldn't be worrying much about getting a flat plot in there. What does it sound like? Where are the real problems, down in the low frequencies or up higher? Is it flutter echo you're trying to kill or boomy, one-note bass? I wouldn't even worry about plots right now actually.

Frank
Old 14th May 2009
  #10
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Re

What I'm getting is a mish mash of sound when we play and am hoping for some clarity by treating the room. Should I run the test again while we are playing? No, that won't work, too much sound at that point. Flutter echo is according to the slap test, somewhat a factor. Also I notice that my monitors are not giving me accurate sound (when I listen with headphones things are much clearer, and yes these are really good monitors). I'm sitting with 12 panels of Knauff here, do I just start bass trapping corners, etc? Thanks again.

Mck
Old 14th May 2009
  #11
JWL
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Start with bass traps in the corners, as I wrote above. Once you get enough of those in the room to flatten it out, you'll likely also have enough absorption at high frequencies to take care of most of the flutter echo. If not, you can spot-treat with thinner panels.
Old 14th May 2009
  #12
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Re

Okay I have funky corners. One is a door corner so no room, the other two are unusable again. Really there is only one vertical corner that can be straddled, although of course I'll be able to some ceiling corner work. This room is very inconveniently designed for bass trapping.
Is the effect equivalent if the panel is sitting right next to the corner? Silly question perhaps. Also will panel thickness make up for the loss of surface area? Cannot do full 2 X 4 sheets, they will have to be cut down to maybe half lengthwise and then I will double thickness to 4". Do I glue them together or not?
FRK panels are useful specifically for bass trapping correct?

I appreciate the help from all.

Mck
Old 14th May 2009
  #13
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Weasel9992's Avatar
 

Quote:
Originally Posted by mckinetic View Post
Is the effect equivalent if the panel is sitting right next to the corner? Silly question perhaps.
Possibly. Placing two traps perpendicular to one another in a corner can have close to the same effect as straddling a corner. If you can't get the vertical corners, then get the corners where the walls meet the ceiling...those are just as valid as the vertical ones. If you can't get any of them, then get as many 4" panels as you can on the parallel walls. I do think that 10 sheets of insulation will not be nearly enough to solve the problem though. I think you could easily double that.

Quote:
Originally Posted by mckinetic View Post
Also will panel thickness make up for the loss of surface area? Cannot do full 2 X 4 sheets, they will have to be cut down to maybe half lengthwise and then I will double thickness to 4". Do I glue them together or not?
No, panel thickness will not make up for loss of surface area. As a matter of fact, greater surface area almost always trumps panel thickness. It's almost always better to cover twice as much area with 4" panels as half as much with 8" panels. No need to glue them together.

Quote:
Originally Posted by mckinetic View Post
FRK panels are useful specifically for bass trapping correct?
I would not use FRK in a practice room. You don't want any more reflectivity than there already is.

Frank
Old 14th May 2009
  #14
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Re

Thank you for the wealth of information. No doubt.

There appears to be some debate as to the usefulness of Ready Bags,
some say they are great others say if you hang them from the ceiling(which
I plan too) they inevitably sag. Any resolution there? Frames are just one more step I was hoping to avoid. If possible. There really is no way to do both sides of a few of the corners. A great apartment otherwise Will doing the ceiling help much? Again, thanks to you all.

Mck
Old 14th May 2009
  #15
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For the 27$ you would spend on a bag, you could build 3 frames and cover them with fabric.

I would ditch the bags.
Old 15th May 2009
  #16
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Re

Thank you for your help. Regarding the framing method, is a plywood front a good idea? Something about not sucking up all the highs...
Old 15th May 2009
  #17
JWL
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Don't cover the front or the back of the absorber with plywood, as you'll reduce the effectiveness. The best frame, acoustically speaking (not structurally) is no frame at all. Cover up as little of the absorbent material as you can.
Old 15th May 2009
  #18
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Re

So this idea of basically putting the panel on a frame and then wrapping it like a burrito is at the least highly efficient and easy? Seems too much so...
I thought this was going to be more difficult. Planning to get started this weekend. Thank you.
Old 15th May 2009
  #19
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Quote:
Originally Posted by mckinetic View Post
So this idea of basically putting the panel on a frame and then wrapping it like a burrito is at the least highly efficient and easy? Seems too much so...
I thought this was going to be more difficult. Planning to get started this weekend. Thank you.
It is definitely effective and easy.

Frank
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