I've done some Googling on Ultra Touch and found much praise of it when it's used in bass traps and box damping applications. However, I couldn't find anything on its use as a closed box volume enhancer.
Checked Pimm's site. Sure looks like an electronics wizard. However, not much there on speaker applications other than some diddling with bits of carpet backing on the undersise of a woofer.
I'll see if I can find some Ultra Touch in my area and will give it a try but I'm not optimistic. Anybody tried melt blown polypropylene? It's safer than FG and about the same fiber diameter (5 um).
Anybody played with activated carbon? KEF has....
Home Technology eMagazine - KEF'S NEW 'ACE' TECHNOLOGY It's All To Do With Size | HomeToys
Home Technology eMagazine - KEF'S NEW 'ACE' TECHNOLOGY It's All To Do With Size | HomeToys
Zeolite and perlite will work in a similar fashion. I also tried Aerogel a few years back with great success. http://www.solar-components.com/aerogel.htm Aerogel(Worlds lightest solid) has way more surface area than anything on the planet..
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Does Perlite Contain Asbestos?
There has been growing concern that perlite may be contaminated with asbestos, making perlite a dangerous product. According to the Perlite Institute, and their continuing tests, the answer is no. The two substances are rarely found together in volcanic rock, according to a 2002 report.
Read more: What Is Perlite? | eHow.com What Is Perlite? | eHow.com
The best way to deal with those products is to fill your wife's pantyhose completely and zip tie the ends. This allows the product to interact fully with the internal air pressure, while keeping dust to an absolute minimum. Oh yeah, put them in the box before she notices, or she'll think your weird.(To late for me!)
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The rigid fiberglass used to make HVAC duct work is better than loose batting per volume filled, but Bonded Logic is even better at the lowest frequencies. They used to have an absorption coefficient table in their website, but I don't see it anymore. Many studio designers are now switching over to the BL from fiberglass.
Greg
Similar stuff(Kind of). Coefficient chart at the bottom..
ECO-CORE Eco Friendly Insulation (4 lbs/ft) 48"x24"x2" -Case of 6
Bonded logic coefficient chart..
http://www.bondedlogic.com/construction-products/acoustical-panels
ECO-CORE Eco Friendly Insulation (4 lbs/ft) 48"x24"x2" -Case of 6
Bonded logic coefficient chart..
http://www.bondedlogic.com/construction-products/acoustical-panels
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I've been using the R-13 rated insulation. See the last page of this PDF for coefficients:
http://www.bondedlogic.com/pdf/denim-insulation/ut-denim-insulation-brochure.pdf
It says that R-13 is 3.5" thick, but it comes out of the package measuring closer to 2-3".
I use rigid panels for my room absorbers, but in filling a 12L box that contains drivers, wires and crossovers means a loose fill. When I originally built these boxes, I still had some ceiling tiles, so they do happen to be lined with 1/2 inch bonded FG. For my next panel absorbers, I will try the bonded cotton as it does have a better spec.
Some speakers, my old Studio 20's for example, had a single piece of open cell foam filling them. Seemed odd being ported speakers. The foam did not look any different than dime store cushion foam.
Again, all three made for this use fibers were very close. Maybe slight differences in reducing reflections from the box, but as far as their ability to reduce the Fs, they worked the same. Two goals, two factors. What I really confirmed is the craft store polyfill is for pillows, not speakers.
If people are looking for further places to take this, you could look to see if the performance varied with size. Do they rank the same when used in a 60L sub box when trying to get from 25 to 20 Hz as the do in a 12L box trying to get from 80 to 70? What is the optimum weight per volume for each material? Know any grad students who need a project?
Some speakers, my old Studio 20's for example, had a single piece of open cell foam filling them. Seemed odd being ported speakers. The foam did not look any different than dime store cushion foam.
Again, all three made for this use fibers were very close. Maybe slight differences in reducing reflections from the box, but as far as their ability to reduce the Fs, they worked the same. Two goals, two factors. What I really confirmed is the craft store polyfill is for pillows, not speakers.
If people are looking for further places to take this, you could look to see if the performance varied with size. Do they rank the same when used in a 60L sub box when trying to get from 25 to 20 Hz as the do in a 12L box trying to get from 80 to 70? What is the optimum weight per volume for each material? Know any grad students who need a project?
Here's a link to a very in depth empirical/theoretical study of FG vs PET in a closed box. Much of the empirical work was done with an AR4x cabinet of about 0.6 cu. ft., twice that of the op's..... FWIW.
http://auralization.blogspot.com/2006/05/confidential-stuff.html?zx=60dfdefb7a7b09f
http://auralization.blogspot.com/ Many photomicrographs of FG and PET included here.
The blogspot site proprietor is that of Ken Kantor, formerly of Acoustic Research, NHT and other well know speaker manufacturers.
http://auralization.blogspot.com/2006/05/confidential-stuff.html?zx=60dfdefb7a7b09f
http://auralization.blogspot.com/ Many photomicrographs of FG and PET included here.
The blogspot site proprietor is that of Ken Kantor, formerly of Acoustic Research, NHT and other well know speaker manufacturers.
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Tvrgeek,
Thanks for sharing your experiences.
I didn't do any measurements but your tests do confirm my experiences too. The slick and springy stuff is the worst - best for couch cushions... Can you post a pic of the cheap poly fill - diyAudio members can avoid that particular "strand"...
I had a thread long time back:
http://www.diyaudio.com/forums/full...-differences-poly-fill-types.html#post2581271
Are we considering lining also as part of the stuffing process? Sorry if that sounds like a silly question, but my understanding is that a TL/MLTL design will need some polyfill to dampen uneven responses; they will need some ling at the back and sides of the driver to absorb early reflections and to dampen the driver backwave, but some stuffing through the line is also required. A BR box will work most of the times with linings on the inside walls only, though I've used small amounts of polyfill to tune a DBR box. Acoustastuff has more consistent/predictable results among the polyfills I've used. Now have some "Dacron Blue" with me also - haven't tried it yet, but it is a bit coarse to touch - which is a good sign vs being really slick like "HCF" types.Too much polyfill gives me the impression that the "life" is getting sucked out of the driver...
For lining I am with P10 on the Ultratouch, the problem is to find the nice 1/2" thick version. I got some 2" thick insulation type Ultratouch and this is not as dense as what P10 uses. Will try with jute carpet underlay next.
Thank You for the Ken Kantor article.
WRT resonances I've experimented with steel wool 4/0 and 2/0. These will unroll to an unbroken and continuous sheet and placed between sheets of fiberglass. Also laid parallel with the longest dimension of the enclosure. Haven't gotten around to measuring if it works.
WRT resonances I've experimented with steel wool 4/0 and 2/0. These will unroll to an unbroken and continuous sheet and placed between sheets of fiberglass. Also laid parallel with the longest dimension of the enclosure. Haven't gotten around to measuring if it works.
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RE: cotton/bonded logic/whatever©
I believe (no science here), that cotton is indeed one of the best. Cotton batting as ive been able to find, is the type used for 'ye olde' quilt making.
I liken it to wool felt, being denser. I think it would be better for wall lining to reduce reflection, unless teased out rather alot. Cotton wool is cheaper though, in smaller amounts.
To maximise the adiabatic effect im not so sure about cotton. I havent tried to tease it out fine enough to be similar to the average BAF density, but I dont see why it wouldnt be possible. GF is a great material, just not good for my athsma, or ecszema.
As I may have posted before, I found great results by stuffing a sealed box with cotton wool balls, a bit of cut up BAF, and a block of PU foam suspended in the centre of the box. For those who doubt the ability of cheap foam, just try it. I used a small 'pillowcase' made (by me) using thin craft felt. This contained the foam and was stapled to the top panel. the stuffing was built around this. Worked like a charm. This was the only way I found to hold the foam in the centre, where it would do the most work.
That little pearl, came from my late fathers' homemade efforts during his time at Goodmans in the 70s. It was one of his better pieces of advice to me
I believe (no science here), that cotton is indeed one of the best. Cotton batting as ive been able to find, is the type used for 'ye olde' quilt making.
I liken it to wool felt, being denser. I think it would be better for wall lining to reduce reflection, unless teased out rather alot. Cotton wool is cheaper though, in smaller amounts.
To maximise the adiabatic effect im not so sure about cotton. I havent tried to tease it out fine enough to be similar to the average BAF density, but I dont see why it wouldnt be possible. GF is a great material, just not good for my athsma, or ecszema.
As I may have posted before, I found great results by stuffing a sealed box with cotton wool balls, a bit of cut up BAF, and a block of PU foam suspended in the centre of the box. For those who doubt the ability of cheap foam, just try it. I used a small 'pillowcase' made (by me) using thin craft felt. This contained the foam and was stapled to the top panel. the stuffing was built around this. Worked like a charm. This was the only way I found to hold the foam in the centre, where it would do the most work.
That little pearl, came from my late fathers' homemade efforts during his time at Goodmans in the 70s. It was one of his better pieces of advice to me
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