Internal Damping

[HiFiNutNut]

Brett,

I have some high quality (with best density) 80% wool 20% polyester 100m thick wool blankets that work very well. I spent a lot of time and tried different suppliers across states and finally found them. I have bought from two wool brands and this is the better one. The supplier warned that many manufacturers claim their products have 75% wool and 25% polyester but infact has real wool content as low as 20%. I think that is true. The material has been compared to others and found to be the best. Stuff them into my woofer box and could not hear any standing waves whatsoever, and the box appears to be disappeared, running 20Hz to 20khz. Polyfill and sound foam are of no comparision, especially at lower frequencies. Natural material is much better than synthetics in absorbing sound. I got this idea originally because John K told me that polyfill was hopeless and wool batts worked well in a U-frame. He obviously did experiments before he concluded this.

I bought two huge bags and used only one. It consists of possible 6 pieces of 2m x 0.5m x 0.1m blankets. If you want, you can have them for the price I got them (roughly about AUD$150 and I consider this to be a real bargain). Send me a PM if you are interested. Better wait for 3-4 weeks because I actually like to use them for damping the floor bounce while doing measurement in the coming a few weeks.

Regards,
Bill

 

[Brett]

Sounds good Bill. Email sent.

Mebbe I can get to hear your speaks when I pick it up too?

 

[Inductor]

Brett,

I have some high quality (with best density) 80% wool 20% polyester 100m thick wool blankets that work very well. I spent a lot of time and tried different suppliers across states and finally found them. I have bought from two wool brands and this is the better one.

Hi Bill,
Do you have a recipe to have it made by hand in a loom, from real wool here in Portugal? What about the amount of compression of the fibers and density, thickness/weight on it (the final wool carpet or tapestry)? Do you have a picture of it?

Another material used in construction...
UltraTouch Natural Cotton Fiber insulation it seems good, at http://www.bondedlogic.com/ultratouch.htm with a NRC (Noise Reduction Coefficient) of .45.

Best.

 

[HiFiNutNut]

Inductor,

I wish I knew how to make them.

There are a companies all over the world that make wool batts. The ones I used are made for sound insulation or if you had bags of money, roof insulations. How to make them would be some propritory information, I would presume, but I have gone through some academic websites and they have texts on how to make them. Google is your source of information.

Regards,
Bill

 

[planet10]

UltraTouch Natural Cotton Fiber insulation

Thanx for that.

We use cotton felt for most of our projects (and sometimes a bit of polyfluff). We have been using stuff recycled from old speaker salvage and need a source for new soon. Turns out the Canadian distib is just down the street from where the father-in-law lived (RIP). I'll arrange to get a sample.

I also have a whack of raw wool, but have not gone to the effort to turn it into something useful. It can be used as fluff (mix with polyfluff to keep it from sagging), or fairly easily made into felt matt (google wool felting).

dave

 

[Svante]

ps. I have been reading your software documentation (The Edge, Xdir and Basta!) and (I remember that) didn't you use to have one software that would resolve the vector summing output and phase shifts of two speakers, and print the x-over frequency curves as a result. Where can I read about this topic, do you know?

Hmm, XDir shows the directivity of the complex sum of two point sources at one frequency. Basta! can show the resulting frequency response in one or more directions of the complex sum of several drivers.

I cannot recall having written some other software for this.