JoeM,
Get it at Spotlight - your best and cheapest choice.
A second choice is Jaycar. I bought some from them.
Hi Guys,
I am looking for wool material stuffing. Where can I find it in Australia? This is kind of funny since Australia is a wool exporter.
I am sure I don't have to spend big dollars to build a wool quilt for speaker stuffing. I need quite a bit of them.
Any advice?
Regards,
Bill
Get it at Spotlight - your best and cheapest choice.
A second choice is Jaycar. I bought some from them.
Hi Guys,
I am looking for wool material stuffing. Where can I find it in Australia? This is kind of funny since Australia is a wool exporter.
I am sure I don't have to spend big dollars to build a wool quilt for speaker stuffing. I need quite a bit of them.
Any advice?
Regards,
Bill
Thanks.
Different materials have different ability to damp resonance at different frequencies and by no means they are linear.
I think polyfill is rather hopeless at low frequencies and wool would be better.
I saw a link long time ago listing the effectiveness of different materials at different frequencies and I have lost that link. If anybody has one please kindly provide it here.
I want to damp the woofer resonance at around 160Hz. I may try ringing up an insulation company.
Regards,
Bill
Different materials have different ability to damp resonance at different frequencies and by no means they are linear.
I think polyfill is rather hopeless at low frequencies and wool would be better.
I saw a link long time ago listing the effectiveness of different materials at different frequencies and I have lost that link. If anybody has one please kindly provide it here.
I want to damp the woofer resonance at around 160Hz. I may try ringing up an insulation company.
Regards,
Bill
Filling material has two effects:
1. It introduces an acoustic resistance which attenuates acoustic resonances ("standing waves").
2. It makes the compression/decompression of air inside the box isothermal, rather than adiabatic; this has the effect that the box appears to have an up to 40% larger volume.
Different materials have different properties. Some materials, like polyfill mainly has the (2) property, others like fiberglass does both (1) and (2). If an assembly instruction suggests polyfill, then using fiberglass will give a response different from the intended. Polyfill is good for bass-reflex subwoofers with a sufficiently low and steep crossover frequency, where standing waves isn't a problem. If it is replaced with fiberglass there is a great chance that the frequency response drops several dB at low frequencies.
1. It introduces an acoustic resistance which attenuates acoustic resonances ("standing waves").
2. It makes the compression/decompression of air inside the box isothermal, rather than adiabatic; this has the effect that the box appears to have an up to 40% larger volume.
Different materials have different properties. Some materials, like polyfill mainly has the (2) property, others like fiberglass does both (1) and (2). If an assembly instruction suggests polyfill, then using fiberglass will give a response different from the intended. Polyfill is good for bass-reflex subwoofers with a sufficiently low and steep crossover frequency, where standing waves isn't a problem. If it is replaced with fiberglass there is a great chance that the frequency response drops several dB at low frequencies.
HiFiNutNut said:
First I should maybe state that I have not examined this first-hand, but I think that wool is more to the both damping and isothermalizing direction, just as fiberglass, so you are probably well off using that too if you are concerned about the properties of fiberglass.
I have myself very little concern using fiberglass for loudspeaker building, compared to the amount in buildings the amount used in speakers is nearly neglectible. I am aware of the debate, though, and you are of course free to make your own choice.
HiFiNutNut said:
Pardon me if I get OT again, I'm, just wondering, I have never been to Sidney and don't know what you insulate houses with there. Do you use fiberglass? You have a climate quite different from ours, I think. Here winters can get to -25 °C and we have 22 cm of fiberglass in the walls and some 50 cm om the attic. When we re-built the house I was up there with a snowshovel moving the fiberglass. For THAT I needed a face mask (I forgot it once and felt it in the lungs afterwards) but otherwise I think the precautions that some people take when building loudspeakers are crazy.
And yes, it is a bit itchy, but not too bad.
Svante,
Here people use fiberglass batts, polyester and wool but wool is more expensive, less popular and getting out of fashion. Australia is an exporter of wool.
I rang up a number of home insulation companies in the past 2 days and I have not got anybody who could supply me any wool! By the look of it, I may end up buying a wool quilt.
Well I have to confess I have never worked with anything else other than polyfill. If wool has very similar acoustic properties as fiberglass, I would choose wool.
What about open cell foam? it is readily available. Does it have the property (1) and (2) as you described?
Regards,
Bill
Here people use fiberglass batts, polyester and wool but wool is more expensive, less popular and getting out of fashion. Australia is an exporter of wool.
I rang up a number of home insulation companies in the past 2 days and I have not got anybody who could supply me any wool! By the look of it, I may end up buying a wool quilt.
Well I have to confess I have never worked with anything else other than polyfill. If wool has very similar acoustic properties as fiberglass, I would choose wool.
What about open cell foam? it is readily available. Does it have the property (1) and (2) as you described?
Regards,
Bill
HiFiNutNut said:
I'm not sure I should answer that , since I really don't know other than by hearsay, and also since there are several types. But guessing/speculating I'd say it is more isothermailzing than damping. More like polyfill, that is.
There is a way to compare materials qualitatively with regard to this, that is not terribly difficult. Take any closed box with any driver in it.
First; empty it completely from any stuffing. Look at the resonance peak at fc in the electrical impedance.
Then add the material you want to investigate. If the resonance peak moves toward lower frequencies, it is isothermalizing, if the height of the peak is lowered it is damping.
Note: a material that is purely isothermalizing should actually have a slight decrease in the peak height too due to a lower Q which in turn depends on the lesser reactance in the resonator (the volume appears larger). This decrease should however typically be less than that for a damping material.
It might be hard to get actual numbers on different materials this way, but one can at least compare them. Also, it only investigates the effects of the materials near the resonance frequency of the woofer.
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