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Old 6th November 2012, 01:16 AM   #11
jbell is offline jbell  United States
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You wouldn't happen to have 9 foot ceilings... and have a 125hz issue as well?
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Old 6th November 2012, 01:30 AM   #12
djn is offline djn  United States
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It is 8ft x 16' x 16'. No problem at 125hz.
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Old 6th November 2012, 01:35 AM   #13
jbell is offline jbell  United States
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a square room with ceiling height at exactly half the room lengths.....

wow, that's about as bad acoustically as it gets...

You sure it's not 280hz?

OC703 in 6"x48" strips wrapped in acoustic fabric spaced 18" OC on the side walls.
OC703 2' wide floor to ceiling triangular across the back 2 corners for bass traps.
Bookshelves with varying depth books across the back wall to give a bit of 'diffusion'
OC703 2'x4' panels on the front wall directly behind the speakers on each side.
Tow your speakers 'in' about 10-20 degrees, with each speaker slightly different angle/distance from outside wall.

Never listen directly in the middle of the room.

good luck

Last edited by jbell; 6th November 2012 at 01:46 AM.
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Old 6th November 2012, 03:14 AM   #14
djn is offline djn  United States
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Quote:
Originally Posted by weltersys View Post
How does the 3" compare with the 2" in sound absorption below 250 Hz?
at the bottom of this post is that data.

Quote:
Originally Posted by tb46 View Post
Hi,

Don't get the room to "dead".

Another reference: http://www.bobgolds.com/AbsorptionCoefficients.htm

I'm attaching the data on OC70x panels.

Regards,
Thanks, that is all good reading.

Quote:
Originally Posted by auplater View Post
I've had much better success with multiple subs than absorbers... easier on the eyes as well.

Placement is the key.

John L.
I would rather do one or the other, but if I have to do both, oh well.

Quote:
Originally Posted by jbell View Post
a square room with ceiling height at exactly half the room lengths.....

wow, that's about as bad acoustically as it gets...

You sure it's not 280hz?
Yep, I know!!! This room is taking some getting use to. My old room was 26' x 34' and designed by Paul Klipsch for the owner who had contracted Paul to consult with him at Ford Motor Company.
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File Type: png Absorption Co..png (16.8 KB, 143 views)
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Old 6th November 2012, 03:17 AM   #15
djn is offline djn  United States
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I just skimmed through a lot of that data and all the absorption data starts at 125hz so that is a sign that it doesn't do much below that.
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Old 6th November 2012, 04:01 AM   #16
jbell is offline jbell  United States
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Originally Posted by djn View Post
I just skimmed through a lot of that data and all the absorption data starts at 125hz so that is a sign that it doesn't do much below that.
I don't trust acoustic data below 125hz for absorption.

Bonded acoustic cotton is absorption snake oil... it's really that good, but you have to be willing to go 3.5" thick to use ultratouch.

Don't over deaden your room, or it will go from weird to freaky. That's the magic of 6" wide acoustic strips on the side walls. It kills the standing waves without going dead.

If you have full creative control over the room surfaces (aka, you don't have someone that will overrule you on what you put in the room.....) Poly cylindrical diffusors are magic, and are about 1000 times better than the bookcase solution. You can make a wall "seem" 20' away. 12" home depot concrete tubes, cut into 3 sections, 1x pine endcaps. Spray it with ceiling texture, and then knock the texture down. The knock down texture looks good, and is full reflective. Paint to match your room. Rear wall only. 18-24" OC. If you have no drywall ability, you can usually contract with a drywall company to come in and shoot them. cheaply.

Again, good luck, you have a challenging room.

Last edited by jbell; 6th November 2012 at 04:04 AM.
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Old 6th November 2012, 11:08 AM   #17
Moonfly is offline Moonfly  Spain
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Quote:
Originally Posted by djn View Post
Hi All, finally settled in the new house and working with a smaller room but still good size. I have two very good subs and all the bits to build two more. I know I have a standing wave at around 250hz so I plan on making good panels with OC703. Most likely 12 of them 2' x 4' x 3".

So I have this thought that I want to explore. I want to go with multiple subs to smooth out the nulls and peaks, BUT.....won't panels do that by absorbing the sound waves???

I can't seem to think this one through.
Bass traps wont do anything about dips/nulls, and eq probably wont either, the only way to fix that is with multiple subs. Eq will help tame peaks pretty effectively. Bass traps can help with peaks, but you would be better off with multi subs and eq as its much easier to implement. Ringing in the room is what bass traps and acoustic treatments are most effective at reducing, and eq wont really tackle a badly ringing room.
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Old 6th November 2012, 02:16 PM   #18
tb46 is offline tb46  United States
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Hi djn,

As jbell pointed out in Post #16 you would be best of to treat the room, and you need to vary between reflective and absorptive areas all around the room. I have made diffusors from 3/8" (cheap) plywood screwed to curved ribs cut from 2x6s and 2x4s (I like the sonotube idea, I would recommend a larger diameter, e.g.: 20".) I filled the back w/ fiberglass, and covered it with burlap (they make nice absorbers too). On the front (convex surface) I used wood stain. I also had them standing on legs so I could move them around easily. They were 3'x8' and 2'x8'. You can always adjust the sizes to fit your room height and decor. Once you get the room sounding the way you like it, you can work with the multiple subs to get the low end "perfect".

Regards,
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Old 6th November 2012, 02:25 PM   #19
djn is offline djn  United States
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Quote:
Originally Posted by jbell View Post
I don't trust acoustic data below 125hz for absorption.

Bonded acoustic cotton is absorption snake oil... it's really that good, but you have to be willing to go 3.5" thick to use ultratouch.

Don't over deaden your room, or it will go from weird to freaky. That's the magic of 6" wide acoustic strips on the side walls. It kills the standing waves without going dead.

If you have full creative control over the room surfaces (aka, you don't have someone that will overrule you on what you put in the room.....) Poly cylindrical diffusors are magic, and are about 1000 times better than the bookcase solution. You can make a wall "seem" 20' away. 12" home depot concrete tubes, cut into 3 sections, 1x pine endcaps. Spray it with ceiling texture, and then knock the texture down. The knock down texture looks good, and is full reflective. Paint to match your room. Rear wall only. 18-24" OC. If you have no drywall ability, you can usually contract with a drywall company to come in and shoot them. cheaply.

Again, good luck, you have a challenging room.
Yep, it is "my" room so no issues there. BUT. The back wall is currently all shelve needed for LP and such. I can't get rid of that for practical purposes. Acctually, the back wall is divided into 3 parts. There going left to right, there are stair going up 7 steps to the kitchen (trilevel), a door going to the storage area that currently is covered in accoustic foam cut in pyrimad shaps, then a 7' wide space that is resest 2'. That is where the 5' wide Ikea bookshelf is.

I agree about being too dead. I don't like that. I like the idea of 6" strips, I never thought about cutting the 24" panels down and those seemed too wide.

The problem with the corner panels is I effictively don't have corners in the back of the room. I do have two nice corners in the front wall, I don't like the looks of corner panels up there and wish I could do something about that look, but I don't know of an alternative to corners.

Quote:
Originally Posted by Moonfly View Post
Bass traps wont do anything about dips/nulls, and eq probably wont either, the only way to fix that is with multiple subs. Eq will help tame peaks pretty effectively. Bass traps can help with peaks, but you would be better off with multi subs and eq as its much easier to implement. Ringing in the room is what bass traps and acoustic treatments are most effective at reducing, and eq wont really tackle a badly ringing room.
Good news on that front, a friend of mine offered me two more good subs so I can add those to the two I have and test the therior out before building two more of my own.
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Last edited by djn; 6th November 2012 at 02:28 PM.
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Old 7th November 2012, 03:00 AM   #20
jbell is offline jbell  United States
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Is this a video and audio room? aka... can the room be flipped and the video/speakers go where the ikea is?

It would be really nice to be able to make the back wall "acoustically disappear" but in your current setup, that sounds out of the question.

Last edited by jbell; 7th November 2012 at 03:08 AM.
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