Because I have the best result with the dynaudio Mw150 driver in 7l volume with angel hair stuffing. Freq. range 225hz to 2100hz. 24db linkwitz riley slope.
If you are using wool, it is always a good idea to make sure it has been treated with insecticide. Because moths are very partial to wool, and the end result can be that the wool turns to moth poop. (Frass, is the correct term, I think.) And that can make a dreadful mess of you drivers.
See below, for example. (And yes, this driver was in a sealed enclosure.)
There should be a “don’t like” button. Ewwwww!
Sealed…I guess that means that the wool was pre-pregnant.
Yuck. Luckily we don't have moths in our area and we have the house sealed up well enough to keep them out.
That is a reason why I'd always cover the back of the driver with grill cloth. Just the fibers of glass wool or rock wool alone are enough to ruin a driver, especially the fancy new ones with exposed VC gaps under the spider. You dont want anything getting in there. Its important to use a light coat of clear satin urethane spray paint to bind the surface if you have exposed glass or roc wool fibers. Just a light top coat will do to keep the fibers together. Hair spray or PVA mold release spray will work in a pinch. The better solution is covering it with grill cloth or nylon panty hose material.
That is a reason why I'd always cover the back of the driver with grill cloth. Just the fibers of glass wool or rock wool alone are enough to ruin a driver, especially the fancy new ones with exposed VC gaps under the spider. You dont want anything getting in there. Its important to use a light coat of clear satin urethane spray paint to bind the surface if you have exposed glass or roc wool fibers. Just a light top coat will do to keep the fibers together. Hair spray or PVA mold release spray will work in a pinch. The better solution is covering it with grill cloth or nylon panty hose material.
Also keep in mind glass or mineral wool is considered a carcinogen and shouldn't be used untreated or uncovered in a ported enclosure. Its nasty stuff.
I did an experiment with a smal ported long throw sub lined with fiberglass and played it pretty loud while holding a bright light next to the port. The fibers were visibly flying out of the port quite a bit. That air born stuff will get into your lungs if you're close enough which can be bad news.
I did an experiment with a smal ported long throw sub lined with fiberglass and played it pretty loud while holding a bright light next to the port. The fibers were visibly flying out of the port quite a bit. That air born stuff will get into your lungs if you're close enough which can be bad news.
Were you able to clean up that driver? Usually spiders are made from treated cotton which can be susceptible to moths. Better ones are made from nomex or other synthetic materials. Hopefully that driver lived on.
Natural cotton wool from the personal hygiene aisle. Best material ever! I used 15-20 grams per litre. I also sang into the enclosure to estimate when it was ready.
do you have a pic or two just to show exactly what you mean?
not sure i get it
so a clear satin urethane spray paint over fiberglass will insure no fibers go fly? maybe best practice is not to use at all? especially since ultratouch denim is more effective...
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Quite possibly. However they got in, they managed to eat all the wool and turn it into what you see in the picture.
@profiguy The spider was undamaged - just dirty! The driver was downfiring in that particular speaker, with a vent in the magnet, so perhaps more of the grot ended up inside the driver than it would in other circumstances. I was able to clean everything up, and the driver still worked OK.
This is by far the most interesting thread I’ve read this entire night. Very informative and fascinating 🧐 😌👍
If you want to know what you are achieving with damping a sealed midrange chamber, just take impedance measurements while filling it. Compare it with the impedance curve of a free air driver to have a reference. Every impedance wiggle you see added with the driver in the enclosure is due to it being in that enclosure. Takes a lot of the 'Voodoo' out of the game, isn't super exiting but very effective to get a great frequency response.
For midrange frequencies, the Twaron Angel hair really is a great product, be it that it is super expensive. As I knew several people at the Twaron plant(*) I could test it (I had to card it like real wool first) and a little does go a long way, you'll see the 'blips' in the impedance disappear. The fluffy fiberglass fill is very effective over the entire frequency band. Nasty stuff though, I sealed it off with a layer of real wool felt. The combination of real wool felt on walls and fiberglass in the middle actually worked better than both materials by themselves.
(*) worked for them as a mechanical engineer in the past.
For midrange frequencies, the Twaron Angel hair really is a great product, be it that it is super expensive. As I knew several people at the Twaron plant(*) I could test it (I had to card it like real wool first) and a little does go a long way, you'll see the 'blips' in the impedance disappear. The fluffy fiberglass fill is very effective over the entire frequency band. Nasty stuff though, I sealed it off with a layer of real wool felt. The combination of real wool felt on walls and fiberglass in the middle actually worked better than both materials by themselves.
(*) worked for them as a mechanical engineer in the past.
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This EPA publication doesn't paint such a bleak picture
https://www.epa.gov/sites/default/files/2016-10/documents/fine-mineral-fibers.pdf
"Animal studies have reported an increase in lung tumors in animals exposed to ceramic fibers by inhalation, while no increase in tumors was reported from exposure to glasswool, rockwool, or slagwool"
"The International Agency for Research on Cancer (IARC) has determined glass filaments, glass wool, rock wool, and slag wool to not be classifiable as to their carcinogenicity to humans (Group 3). The National Toxicology Program (NTP) has classified certain glasswool fibers (inhalable fibers that are biopersistent in the respiratory system) as reasonably anticipated to be human carcinogens."
So for a reasonable apprehension to be carcinogenic the fiber needs to be bio-persistent which very few are.
While I wouldn't suggest anyone any risk they are not comfortable with, keeping glass fibre inside an enclosure is ridiculously easy (for all practical purposes) and a quick google of the risks should put all but the most paranoid mind at ease.
Of course there are other suitable fibres but I don't think anyone wants those in their lungs either.
Sure, the label glass or mineral wool given by the EPA as not being a direct carcinogen, but based on its persistence as a lung irritant, the fibers have a good chance of getting stuck in your lung tissue and not shed by the mucous ie. sort of what asbestos, carbide dust or other fine particle substances do, even wood smoke.
So we're technically not dealing with an organic carcinogen, but a substance that has the propensity to provoke tumor formation. That in itself is enough reason for me to handle it appropriately, being an asthmatic myself. This makes my body type more prone to these issues. After all, chronic inflammation and irritation anywhere in your body can lead to tumors and cancer, so can anything that is a known irritant can provoke it.
I've known two people who have passed away from cancer having worked in the insulation business. They both have mainly worked with blown fiberglass and mineral wool. An autopsy on one revealed fiberglass strands embedded in his lung tissue with no other substances present. He never smoked or worked with asbestos either, so it was the only recognized foreign substance in his body.
That being said, I'd always use a substitute for rockwool or fiberglass when available ie. cotton insulation. If I have to use it, I'd always bind it on the surface and / or cover it with an acoustically poros layer like grille cloth. As I said before, the dust and fibers of the stuff can get into your driver and deteriorate the moving parts abrasively, especially fiberglass VC formers. It also has the tendency to suck out alot of desired lower midrange response if used liberally to combat a resonance issue or high Qts / Qtc. It has its place, but I just prefer not to use it when possible.
So we're technically not dealing with an organic carcinogen, but a substance that has the propensity to provoke tumor formation. That in itself is enough reason for me to handle it appropriately, being an asthmatic myself. This makes my body type more prone to these issues. After all, chronic inflammation and irritation anywhere in your body can lead to tumors and cancer, so can anything that is a known irritant can provoke it.
I've known two people who have passed away from cancer having worked in the insulation business. They both have mainly worked with blown fiberglass and mineral wool. An autopsy on one revealed fiberglass strands embedded in his lung tissue with no other substances present. He never smoked or worked with asbestos either, so it was the only recognized foreign substance in his body.
That being said, I'd always use a substitute for rockwool or fiberglass when available ie. cotton insulation. If I have to use it, I'd always bind it on the surface and / or cover it with an acoustically poros layer like grille cloth. As I said before, the dust and fibers of the stuff can get into your driver and deteriorate the moving parts abrasively, especially fiberglass VC formers. It also has the tendency to suck out alot of desired lower midrange response if used liberally to combat a resonance issue or high Qts / Qtc. It has its place, but I just prefer not to use it when possible.
mucus? the cells that "Clean" the alveola in the lungs are called macrophages
its not the mucus that clean it, the mucus blocks large particles, like fiberglass, to ever reach the alveola.
I think your right that some material can be super dangerous.
the funny thing is if i remember corerctly, cotton is harder for the macrophage to clean then fiberglass
Yes, mucous is the carrier to move it out of the lungs. Some people react based on auto immune issues to benign substances ie asthma, or the mucous production is insufficient. Thats when stuff gets stuck in the lung tissue, when things start going sour. Some particles are more prone to getting stuck like asbestos with its barb like hooks. Fiberglass can be small enough to get stuck, especially if mucous production isn't sufficient to carry it out. Older, broken down or shredded fiberglass is worse, especially when its ripped apart by sanding or machining. Whole fresh sheets of it are less of an issue.
Hey, im doing standmount speaker (vented) and sometimes we have moths in summertime. I was thinking of using wool inside as stuffing, ut after seeing that picture..
Would it make any sense to cover speaker vent from inside the speaker with acoustic speaker cloth? (like used in speaker grills)
Or metallic grill like with car speakers?
Could this possibly harm speaker effiency, or how low speaker can go?
Any other suggestions that could work?
At least it could keep moth away..
Would it make any sense to cover speaker vent from inside the speaker with acoustic speaker cloth? (like used in speaker grills)
Or metallic grill like with car speakers?
Could this possibly harm speaker effiency, or how low speaker can go?
Any other suggestions that could work?
At least it could keep moth away..
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Grille cloth would be better as its a synthetic material and allows for good airflow if the surface area is sufficient. Restricting airflow at the vent will create a more dampened system, reducing efficiency but improving impulse response (to a point). More restriction will eventually turn it into a critically dampened system with a lower Qtc. The double impedance peaks will gradually turn into a single lower peak of a sealed box as the restriction is further increased. Eventually it will turn into a regular sealed enclosure.
There is a big difference in the materials manufactured today vs 20 years ago. All fibreglass made in Australia since 2001 is bio soluble and the stuff I bought that was manufactured in Turkey was the same, that manufacturer Knauf claims their ECOWOOL is made of non classified fibres that are less persistent than everyday dust. Within Europe there is the European Certification Board of Mineral Wool Products that inspects and certifies products to meet stands relating to the fibres. I imagine there would be similar bodies elsewhere.
Bio soluble fibreglass???
They use bio soluble binders. Not fiberglass and not rockwool(as in melted stone product). Your body does not break down those, and neither does nature to a applicable degree.
And yes Fibreglass particles are bad, Carbon fiber particles even nastier again. You can feel what they do to your skin, fibers gets stuck in the pores and don't break down, embedded in your body permanently in some cases. It is very optimistic to think your organs on the inside of your body is more resistant, then your skin which is relatively robust.
And your lungs are always in movement, contracts and inflates, meaning they will over time disappear into the soft mushy tissue and blood vessel most likely. Mucus is generally from your throat, and what does not stick on the hairs in the throat generally goes into the lungs while you breath.
There is also boards, regulatory bodies and scientists working on a lot of things.
After the last 3 years, it's a wonder that anyone believes they're credibility in general🤣
The Knauf products ( ECOSE® Technology) means that the binder in the insulation is bio soluble, not the glass or stone fibres. It is softer, less dusty and itch less so the fibers are more gentle. And it does not use formaldehyde or phenols in the binder, which is visible from the brown color vs traditional yellow. And is why it is 'ECO' since it has low amounts of so called VOCs (volatile organic compounds).
Those that are treated with fire retarding chemicals have yet another nasty mix of chemicals.
I'm not overly concerned about insulation, but to think it is not harmful to breathe in the particles, is very optimistic 🙂