Steel wool is a much better conductor of heat than the usual absorbent materials.
Using steel wool as an absorbent in a sealed enclosure would therefore facilitate the transfer of heat from the air to the absorbent.
An interesting experiment may be to incorporate fine copper strands into an absorbent material such as polyester wadding.
Modified fine denier tights work well in this role!
Whatever material is used, silk screen mesh would be an effective way to contain fibres from internal components or escaping through the port.
First time that I saw fine steel wool ignited, it was fascinating. But how? Anyway, it would be tempting as an experiment, but let's not forget what we have learned about such ideas and magnetism. >>>> Just watch that stuff easily find its way in tiny particles to magnets of your drivers! That didn't exactly happen to me but close enough. I was lightly touching up the outside of a finished speaker that I made, only to find that some of the steel wool particles went right to the dome tweeter and stuck there magnetically! Go ahead try to gently remove this from the strong attraction of the magnet behind the dome.
Steel wool would work better for dispersing rather than absorbing , I think.
Fine steel wool burns so readily because there is a large surface area of 'fuel' which is exposed to the oxygen in the air.
The air in the enclosure is heated by compression, but this heat would conduct readily into the steel wool.
This transfer of heat keeps the air at the same temperature, providing isothermal (equal temperature) loading.
An unstuffed sealed enclosure is adiabatic, meaning the heat does not leave the air.
Yep. If there's too much stuffing, assymetry in compression vs decompression could lead to distortion. Hence the need to listen and balance competing needs like reducing resonances vs keeping distortion low.
I think something similar occurs with bass reflex ports: during 1 cycle of sinusoidal air motion through the port, the velocity actually has 2 peaks, leading to frequency doubling.
I think something similar occurs with bass reflex ports: during 1 cycle of sinusoidal air motion through the port, the velocity actually has 2 peaks, leading to frequency doubling.
Just a thought... Would homemade cotton bats work? Use regular cotton wool and cheesecloth to make bats of the desired thickness and size. It would almost be like making a quilt.
IME, for full/wide range use mineral wool made the sound dead with overly dense tonality, no matter how or where it was used, polyester was better sounding but not as effective.
Sheep's wool gave best results, strong damping effect (clean sounding) with natural, clear tone.
Cotton may be similar, never tried.
Sheep's wool gave best results, strong damping effect (clean sounding) with natural, clear tone.
Cotton may be similar, never tried.
Glass wool was most effective at lowering Q in this test.
https://www.diyaudio.com/community/threads/stuffing-test-report.218881/page-4#post-3151058
Someone reports their testing showed most of stuffing effects on Q come from resistive damping (IIUC lowered Qms), rather than thermal effects.
https://www.diyaudio.com/community/threads/mucho-polyfill-affect-sealed-sub-q.111897/post-1359729
Could negative subjective effects of mineral wool come from added non-linear mechanical damping and efficiency loss?
https://www.diyaudio.com/community/threads/stuffing-test-report.218881/page-4#post-3151058
Someone reports their testing showed most of stuffing effects on Q come from resistive damping (IIUC lowered Qms), rather than thermal effects.
https://www.diyaudio.com/community/threads/mucho-polyfill-affect-sealed-sub-q.111897/post-1359729
Could negative subjective effects of mineral wool come from added non-linear mechanical damping and efficiency loss?
How would aluminum work in an adiabatic world then? If the aluminum dicipates heat faster inside a subwoofer enclosure would anybody know?
In practice, I would not advocate stuffing an enclosure with aluminium strands (or steel wool for that matter!).
Even wool is a better conductor of heat than air, and will provide an approximation of isothermal operation.
Speaking theoretically, an efficient transfer of heat from the air to the absorbent would keep the air at constant temperature.
Boyle's Law for a confined gas says that, at constant temperature, the product of pressure and volume remains constant, hence the air in the enclosure will compress and rarify in a non-random manner.
Some believe that isothermal operation promotes a cleaner bass response. However this, like most matters to do with loudspeakers, is open to discussion!
Last edited:
It was meant as a hypothetical about heat dissipation I hope nobody would actually try acoustically treating with metals.
Thanks again Galu. I will read your post a second time to better absorb all of it.
I've been thinking of doing some kind of a multi layer for my treatments, having about one inch of RW at the back, or the bottom depending how you look at it. Or even say 1/2" RW to fill half followed by a natural cotton or something similar over top to fill the other half. I figure that might prevent or help prevent RW particles from getting air born. What do you think?
These panels don't have a whole lot of depth, a mere 3 1/2" x a couple of feet. These are supposed to go on the wall directly behind stand mounts. I cut enough to have an extra one.
These panels don't have a whole lot of depth, a mere 3 1/2" x a couple of feet. These are supposed to go on the wall directly behind stand mounts. I cut enough to have an extra one.
Attachments
![20230521_160619[6519].jpg](/community/data/attachments/1084/1084358-5c7e1a16313e252b267bbd939533976d.jpg?hash=XH4aFjE-JS)
The homes I had in Tacoma Washington had rockwool for insulation, the copper smelter probably had lots of it to offer, eventually becoming an EPA superfund cleanup project.
Sealed, I will use common fiberglass insulation, ported, cotton.
Bubble wrap is also effective, and is great in car doors where moisture is possible. A loosely rolled bundle can even be an improvement when used with the other materials.
Sealed, I will use common fiberglass insulation, ported, cotton.
Bubble wrap is also effective, and is great in car doors where moisture is possible. A loosely rolled bundle can even be an improvement when used with the other materials.
The closed cell structure may convert sound energy to heat as the cell content, air, is alternately compressed and rarefied by the sound pressure wave.
Last edited:
Some damping materials are only effective at high frequencies e.g. closed cell acoustic foam.
Others are more effective at low frequencies e.g. loudspeaker felt or dense fibreglass.
Others are more effective at low frequencies e.g. loudspeaker felt or dense fibreglass.
I like to use dynamat on metal car surfaces ie under the carpet trunk and doors inner firewall and behind kick panels. The multi colour insulation they used to install is junk plus it ways a lot , it holds moisture too, all bad.
I'll make a quick comment and it is not meant to be argumentative.
The original post was not very precise in the question posed. Unfortunately the word "dampen' has a technical meaning that is frequently missed (it is also over-used).
You need to go back to fundamentals and ask Why is this material being used?
Is it to absorb sound within the cabinet and prevent internal echoes across a certain spectra region?
Is it to prevent sound transmission from inside the cabinet -to the panels and then- to the outside room?
Is it to prevent possible standing waves within the cabinet?
Is it to stiffen the cabinet and prevent the cabinet from vibrating?
Is it to provide mass to the cabinet and prevent cabinet vibrations in certain spectral regions?.
Is it to provide a different density to the air inside the cabinet and make the volume of the cabinet "seem larger"?
These are all very different goals (and some not easily achieved). Some of the materials suggested in the above posts, completely miss the mark. However in all fairness, the question of why do we put "stuff" in the cabinet was never specified.
I usually assume the cabinet is well-constructed (sufficient mass and stiffness). I'm also used to cabinets that are ported or some reactance annulling is desired. So in my case (and I don't know about the original poster), the last point about making the cabinet "seem larger" is critical. In that scenario, pressed fiberglas or rockwool is the material of choice and I would not bother with most of the other suggestions.
Again, this was meant to be helpful and not argumentative.
The original post was not very precise in the question posed. Unfortunately the word "dampen' has a technical meaning that is frequently missed (it is also over-used).
You need to go back to fundamentals and ask Why is this material being used?
Is it to absorb sound within the cabinet and prevent internal echoes across a certain spectra region?
Is it to prevent sound transmission from inside the cabinet -to the panels and then- to the outside room?
Is it to prevent possible standing waves within the cabinet?
Is it to stiffen the cabinet and prevent the cabinet from vibrating?
Is it to provide mass to the cabinet and prevent cabinet vibrations in certain spectral regions?.
Is it to provide a different density to the air inside the cabinet and make the volume of the cabinet "seem larger"?
These are all very different goals (and some not easily achieved). Some of the materials suggested in the above posts, completely miss the mark. However in all fairness, the question of why do we put "stuff" in the cabinet was never specified.
I usually assume the cabinet is well-constructed (sufficient mass and stiffness). I'm also used to cabinets that are ported or some reactance annulling is desired. So in my case (and I don't know about the original poster), the last point about making the cabinet "seem larger" is critical. In that scenario, pressed fiberglas or rockwool is the material of choice and I would not bother with most of the other suggestions.
Again, this was meant to be helpful and not argumentative.