Help me understand this..
In many of my first building attempts, I used poly fill, which included pillow filling and quilting material. (1" thick so to double/triple layers for adjustments) The only time that I seen much difference was when I stuffed the enclosure almost totally full..
Being curious one day, I grabbed a handful of pillow stuffing and held it in front of a driver and listened, before and after, and didn't notice much difference. Did the same thing with some of the quilting poly folded over three/four times. Both were almost acoustically transparent..
A friend of mine repairs furniture and I noticed that he had some cotton batting on his shelf. I bought some from him and took that home to experiment with. My first test was to hold a chunk in front of a driver. The cotton highly attenuated sound from he driver. I've been using it ever since with great results..
So, what's all the hype with using poly fill beyond taking up a little room inside of an enclosure? Maybe for fine tuning internal volume?
In many of my first building attempts, I used poly fill, which included pillow filling and quilting material. (1" thick so to double/triple layers for adjustments) The only time that I seen much difference was when I stuffed the enclosure almost totally full..
Being curious one day, I grabbed a handful of pillow stuffing and held it in front of a driver and listened, before and after, and didn't notice much difference. Did the same thing with some of the quilting poly folded over three/four times. Both were almost acoustically transparent..
A friend of mine repairs furniture and I noticed that he had some cotton batting on his shelf. I bought some from him and took that home to experiment with. My first test was to hold a chunk in front of a driver. The cotton highly attenuated sound from he driver. I've been using it ever since with great results..
So, what's all the hype with using poly fill beyond taking up a little room inside of an enclosure? Maybe for fine tuning internal volume?
Polyfill has too low density, too much airspace. Moving air molecules are not sufficiently diverted by the fibers because they can move around the fibers with minimal compression. So there is minimal friction and minimal acoustic damping.
Polyfill is designed to remain fluffy, to support a head, to keep the quilt thick over the years without matting down. The strands are twisted and thick to make the most space possible. That's the opposite of what speaker damping needs.
Acoustuff from PE is better, it is much denser, thinner fibers, tangled better, physically behaves more like cotton ball, but not as dense. I have tried cotton insulation (recycled blue jeans) a couple times, and always found it to be too strong. Maybe a 1" thickness inside a big box would be OK, but it is very powerful, very dense, efficient at converting motion of air molecules to heat, thus damping sound vibrations. I have also found it more powerful for room treatment than Dow panels.
I usually use Acoustuff for horns, or just soft thin pink FG for boxes, the kind that comes in the small roll from the home center. It absorbs pretty well but not too much.
I was always intrigued by the very stiff damping boards like No-Rez and Blackhole. Very expensive so I've not tried it yet.
Polyfill is designed to remain fluffy, to support a head, to keep the quilt thick over the years without matting down. The strands are twisted and thick to make the most space possible. That's the opposite of what speaker damping needs.
Acoustuff from PE is better, it is much denser, thinner fibers, tangled better, physically behaves more like cotton ball, but not as dense. I have tried cotton insulation (recycled blue jeans) a couple times, and always found it to be too strong. Maybe a 1" thickness inside a big box would be OK, but it is very powerful, very dense, efficient at converting motion of air molecules to heat, thus damping sound vibrations. I have also found it more powerful for room treatment than Dow panels.
I usually use Acoustuff for horns, or just soft thin pink FG for boxes, the kind that comes in the small roll from the home center. It absorbs pretty well but not too much.
I was always intrigued by the very stiff damping boards like No-Rez and Blackhole. Very expensive so I've not tried it yet.
Thanks, Richidoo. I've read posts stating poly fill and assumed pillow fill. It's pretty much worthless, IMO, after playing around with the cotton batting..
Been experimenting with polyester (Fake Felt) sheets. It's thin and seems to do a pretty good job..
Discount School Supply - 6" x 9" Easy Felt Sheets - 100 Sheets
Been experimenting with polyester (Fake Felt) sheets. It's thin and seems to do a pretty good job..
Discount School Supply - 6" x 9" Easy Felt Sheets - 100 Sheets
Your probably missing the important specification on the filling material.
GSM - Grams per Square Meter.
Most 'poly fill' will be around 150gsm.
Most speaker projects call for around 350gsm.
In the early days it was wool that was used.
Synthetics came about due to cost and vermin.
GSM - Grams per Square Meter.
Most 'poly fill' will be around 150gsm.
Most speaker projects call for around 350gsm.
In the early days it was wool that was used.
Synthetics came about due to cost and vermin.
I'm sure that I'm missing lots of things. I'm just a student trying to get a grasp on all of this. Thanks to folks like you, I'm learning..
Just make sure the 'folks like me' are actually telling you the right thing 😉
God knows our memories could be as faulty a cheap radio.
Never hurts to have a dig around and see if 'statements' can be independently verified or debunked.
So much of what was 'common' knowledge seems to have disappeared these days.
Why ?
Have the oldies with the info taken it to their grave ?
Do the youngens not care ?
Have we all become 'matrixed' where we need the constant spoon feed of just what we need to know there and then...
"You want the truth, You can't handle the truth"
"It's above your pay grade"
"I don't pay you to think"
etc and so on.........
God knows our memories could be as faulty a cheap radio.
Never hurts to have a dig around and see if 'statements' can be independently verified or debunked.
So much of what was 'common' knowledge seems to have disappeared these days.
Why ?
Have the oldies with the info taken it to their grave ?
Do the youngens not care ?
Have we all become 'matrixed' where we need the constant spoon feed of just what we need to know there and then...
"You want the truth, You can't handle the truth"
"It's above your pay grade"
"I don't pay you to think"
etc and so on.........
I'm teaching myself in stages. Right now it's Enclosures/Damping, hence my interest in damping materials. Trial and error will build my conclusions. Hopefully someday I can pass on some valid information..
I started into this late. I'm 50+ so I don't have time for BS. I can only try to figure it out for myself..
The tough part is trying to sort it out. I respect everyone here because I know that that they know much more than myself and everyone has their own aspects on what works "For Them". I need to become knowledgeable enough to find mine..
It's tough for a noob on a limited budget trying to move beyond cardboard.. 😉
Thanks again..
I started into this late. I'm 50+ so I don't have time for BS. I can only try to figure it out for myself..
The tough part is trying to sort it out. I respect everyone here because I know that that they know much more than myself and everyone has their own aspects on what works "For Them". I need to become knowledgeable enough to find mine..
It's tough for a noob on a limited budget trying to move beyond cardboard.. 😉
Thanks again..
My suggestion (using your given example) is to place a piece of cardboard in front of the driver and see how much it attenuates the sound, then ponder whether it would be useful in the cabinet as absorption.
You can't putany damping into a m^2, as it has no volume. I am sure you intended to say m^3?
dave
Actually, that might work pretty good! Never thought of that..
My cardboard statement actually meant growing from cardboard boxes to real enclosures, with a touch of humor.. 😀
LOL.
Thanks Dave.
See, exactly my point about us oldies not getting stuff right.
(I'm 47)
In some areas I'm sure I've forgotten more than some will ever know..
Doesn't help when I get my 2d confused with my 3d..........
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