making absorbers

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axeman_ukl

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can you make these with a sheet of mdf a layer of insulation and covered in fabric ?(solid backed)

or do they have to be a frame open backed and fabric on the front with insulation in the middle ?
 
axeman_ukl said:
can you make these with a sheet of mdf a layer of insulation and covered in fabric ?(solid backed)

or do they have to be a frame open backed and fabric on the front with insulation in the middle ?
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more will chime in, but solid-backed would almost be the same as mounting an open-back panel right up against the wall. as long as there's an air gap of some sort behind the insulation, it should be okay. just so you know, it *is* recommended that you mount an open-back panel away from the wall for better broadband absorption. what you want to do should be fine though.
 
BillyBo said:
more will chime in, but solid-backed would almost be the same as mounting an open-back panel right up against the wall. as long as there's an air gap of some sort behind the insulation, it should be okay. just so you know, it *is* recommended that you mount an open-back panel away from the wall for better broadband absorption. what you want to do should be fine though.
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I agree. It should be fine, but i wouldn't recommend it. An air-gap is the simplest and cheapest(free) way to increase the low frequency absorption of panels. The only use of a solid back is for flexibility and for gobos to provide a very slight degree of isolation between sound sources. I'd always go for open-back panels. This is how I'm making my panels(I'll be selling some in the future). I had this exact idea before i saw the video. I sew my material for a more professional finish.

Mounting the frame behind leaves the edges exposed for more absorption. :D
 
The absorption (like the rigid fiberglass) acts by reducing the velocity of the wave. Therefore you need to place your absorption somewhere where the velocity is at its greatest (which will vary depending on the frequency).

By introducing a solid object (like a wall or panel), you are creating a velocity minimum and thus placing your absorbers here would reduce the effectiveness of your absorption.

These type of absorbers are best placed with a gap of air between them and the wall. Therefore I would personally use an open backed panel spaced from the wall.

Hope that made sense...
 
i was thinking of using 30 mm wickes heavy density slab is this a good choice or overkill
 
pandamonk said:
What rigid fiberglass did you use, and where did you get it? I used Knauf rocksilk RS45 from rowan timber(10 for £20).
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Rockwool RWA45, from a bloke on a building site in London :D I have about 16 100mm thick slabs, and like 10 50mm thick, or something like that. Think I paid the guy £30 but I can't remember.

I haven't made most of them yet, I'm waiting to convert my garage to do them all :) Hopefully that'll be this summer, and of course I'll photograph it all and have a thread on here
 
axeman_ukl said:
i was thinking of using 30 mm wickes heavy density slab is this a good choice or overkill
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I think it's OK, but I decided it was too thin for my liking and it worked out fairly expensive. Maybe look around for something on eBay?
 
axeman_ukl said:
i was thinking of using 30 mm wickes heavy density slab is this a good choice or overkill
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I'd stick to 50-100mm slabs. Like i said, look out for knauf rocksilk. It's fine and it's pretty cheap!
 
pezking said:
Rockwool RWA45, from a bloke on a building site in London :D I have about 16 100mm thick slabs, and like 10 50mm thick, or something like that. Think I paid the guy £30 but I can't remember.

I haven't made most of them yet, I'm waiting to convert my garage to do them all :) Hopefully that'll be this summer, and of course I'll photograph it all and have a thread on here
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Lucky! :cool:

Sounds good. Look forward to seeing it.
 
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