damping material

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is polyester adequate to stop standing waves and the boxy coloration? what frequencies is it effective?

What other materials than fibreglass can be used?

and what does boxy coloration sound like? what frequencies does it affect?
Polyester wool work but sheep wool is best. Black for darker sound:cool:

Talk into a empty box and you will hear.

Frequency with wave length smaller than half of inner size dimensions. Wave length=f/c. c=343 [m/s], f=frequency
 
it says its 80% recycled denim. whats the 20%?

and where can this be bought? preferably in UK.

thanks
In this case 80% denim+20% others (supposing it's cotton).
The industry is selling for many uses, like for garages (to clean the oil).
The properties are some what different between wool, cotton and rockwool (use this instead of glasswool).
Here pics of recycled cotton.:)
 

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I agree with ultratouch. It has a significant higher absorption in 100 to 250Hz range than Dracon, Accustuff,wool etc. I used it for sound absorption in my room quite effectively. May be not the best choice for vented or TL as it will absorb to much of the low frequencies. Another new material is Angelhair (not from the haven but twaron) expensive but not much is required. I tried 8g/l in a closed box for mids and up.
 
I've had a lot of success with this recently:

www.diy.com.ECO-Sheeps-wool-Insulation

I've always had mixed results with polyester based stuff. This seems to work better at those troublesome lower mid frequencies for me.

Pure sheep's wool is a lot of work to get to the right density, it tends to clump. This stuff teases out pretty well as it has polyester too. Haven't tried the recycled denim though.
 
I agree with ultratouch. It has a significant higher absorption in 100 to 250Hz range than Dracon, Accustuff,wool etc. I used it for sound absorption in my room quite effectively. May be not the best choice for vented or TL as it will absorb to much of the low frequencies. Another new material is Angelhair (not from the haven but twaron) expensive but not much is required. I tried 8g/l in a closed box for mids and up.

why dont they state what material angel hair is? I would not use something I dont know anything about. Can ultratouch be used for a bass trap in the room too?
 
Since damping ability is related to the relative thickness of any damping to the wavelength absorbed all damping material is less effective.

dave

yes but fibreglass is still more absorbent at the lowest bass frequencies compared with ultratouch no? Ive seen a graph showing the comparison. So what can be done about this? Can we try to use many layers of ultratouch to increase the bass absorption in the cabinet? I dont want to use fibreglass
 
yes but fibreglass is still more absorbent at the lowest bass frequencies compared with ultratouch no? Ive seen a graph showing the comparison. So what can be done about this? Can we try to use many layers of ultratouch to increase the bass absorption in the cabinet? I dont want to use fibreglass
As you said the type off the box is more important here for the kind and thickness of the absorption material. Follow instructions for a BR enclosure if you have one. Absorption material in quantity are for other types of boxes as was mentioned before, like for closed ones. You are doing a mistake, I think, and you will end with a closed box like type with no Helmholtz/vent effect as Dave said.
 
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I found this is available in CanadianTire, is it what you talk about?

That the flattire store carries it is very good info. That is the stuff you'd ude for volume fill... we mostly use the 1/2" felt as opposed to the less dense wall insulation you have pointed out. But i did just buy a bale of that for sealed boxes.

dave
 
Box Stuffing vs. Lining Notes

The purpose of fluffy stuffing a box is to make it acoustically bigger by retarding sound velocity and/or increasing air load mass, not by reducing sound intensity. A dense boundary layer of acoustical resistance material suppresses wave reflection by converting acoustic energy to heat. Note that a reflected wave travels through this layer twice as its intensity becomes diminished. Typical layer thickness is 1". For bass reflex applications I prefer to use a wool felt liner. For closed boxes, an application of a combination of both stuffing and liner may be beneficial. If the wavelength of the upper frequency bound is greater the box dimensions, then application of a liner is of negligible benefit.

Regards,

WHG
 
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