OK, for your 150 hZ trap change the spacing between slats to 7/16", keep all other dimensions the same.
For your 300 hZ trap, change the spacing between slats to 5/8", keep all other dimensions as they were stated.
That should do it... Steve
follow up on a lot of help from Knight
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terrible_buddhist
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it just occured to me...the slats themselves should be made from mdf? You said the dimensions should be 5.5" X .75"...I thought the slats could be make from ply wood...let me know...also, is it ok for the insulation to touch the slats?
GREAT news btw...finally found mineral wool; its under a different name...but right down the street! I will be posting that info shortly.
GREAT news btw...finally found mineral wool; its under a different name...but right down the street! I will be posting that info shortly.
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knightfly
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The slats can be made from anything you can cut a clean edge on - even concrete, if you had a slab saw.
The insulation should NOT touch the slats, it needs to be mounted so it stays about an inch away. The only thing touching the slats besides the frame they are mounted to, is the cloth that goes on just before the slats are fastened. This is an integral part of the design.
Thanks for posting any and all material sources you have, BTW... Steve
The insulation should NOT touch the slats, it needs to be mounted so it stays about an inch away. The only thing touching the slats besides the frame they are mounted to, is the cloth that goes on just before the slats are fastened. This is an integral part of the design.
Thanks for posting any and all material sources you have, BTW... Steve
Last edited by knightfly on Wed Feb 25, 2004 10:06 am, edited 1 time in total.
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terrible_buddhist
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hmmm...what is your recomendation for keeping the 6 1/4 inch R-19 insualtion in place?
Also, on another thread, I had asked if it was ok to attach the slats at the shallowest end right to the back of the box rather than to beveling a 2 x 1...the response from another poster was this would be ok...but I really like to get your approval on stuff first
Also, on another thread, I had asked if it was ok to attach the slats at the shallowest end right to the back of the box rather than to beveling a 2 x 1...the response from another poster was this would be ok...but I really like to get your approval on stuff first
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knightfly
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Kieth, I just re-read my statements and then re-checked Everest's info on helmholz absorbers, and I goofed. Un-perforated absorbers (panel traps) need the air gap between the front panel and the absorbent, but having the absorbent touch the slats (or perforated face, for other types) in a helmholz actually helps minimise resonances in the slats.
One way to keep the insulation in place toward the front of the absorber would be (where it's deeper than 5 inches from the inside of the slats to the back of the box) mount a 2x4 vertically from bottom to top of the trap, with its face 5" behind the slat mounting position, placing one of these 2x4's every foot apart. If you line these up so that they coincide with the edges of the insulation batts, you can staple the backing of the batts to this inner frame and leave the loose fiberglas facing to the front so it lightly touches the cloth cover (even bows it out a bit till the slats are fastened in place)
As for the beveled pieces, I would NOT attempt to fasten the slats without them. You want a firm fastening on the slats, so they don't resonate at the joint and cause buzzes and rattles.
Sorry about the mixup, and thanks for keeping at it til I get it right...
Steve
One way to keep the insulation in place toward the front of the absorber would be (where it's deeper than 5 inches from the inside of the slats to the back of the box) mount a 2x4 vertically from bottom to top of the trap, with its face 5" behind the slat mounting position, placing one of these 2x4's every foot apart. If you line these up so that they coincide with the edges of the insulation batts, you can staple the backing of the batts to this inner frame and leave the loose fiberglas facing to the front so it lightly touches the cloth cover (even bows it out a bit till the slats are fastened in place)
As for the beveled pieces, I would NOT attempt to fasten the slats without them. You want a firm fastening on the slats, so they don't resonate at the joint and cause buzzes and rattles.
Sorry about the mixup, and thanks for keeping at it til I get it right...
Steve