Speaker Fill- Polyfill vs. Old Fiberglass Fill

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Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby snitch56 » Sat Mar 16, 2013 3:31 pm

Driving to work last week a couple of Altec Corona speakers (circa early 1970's) caught my eye sitting out on the curb waiting to be collected by the garbage man. Unfortunately it was lightly raining outside so they were wet. I took them all apart once I got to work and removed the old insulation inside them. Since they are solid wood no damage was done to the cabinets and the woofers dried out nicely. The tweeters will need replacement (paper cones are soft) along will the grill cloth. My question is, should I dry out the fiberglass insulation and reinstall or just replace it with the new Polyfill stuff? The current insulation is not formed and just appears to be randomly thrown in the speakers.
Thanks in advance,
Brad
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby Geek » Sat Mar 16, 2013 5:29 pm

Polyfluff.

Fibreglass can cause allergy problems and is declared a carcinogen in many countries.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby EWBrown » Sun Mar 17, 2013 7:00 am

The poly fill / polyfluff is also available at pet shops, as a "dacron filter material" for aquarium filters,
fiberglass is itchy, at best, and downright nasty stuff at worst. =:o (666)

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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby Geek » Sun Mar 17, 2013 5:06 pm

I've found 5# bags of polyfloof at Value Village for $2 and Wal-Mart sells it too.

A lot of new speaker designs (especially TL's) call for a certain amount of g/M^2 or oz/ft^2 for optimum performance.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby nyazzip » Sun Mar 17, 2013 7:04 pm

my Dynaco a25 are lined with fiberglass sheet which seems quite dense and fragile, about 2.5-3"(60-80mm?) thick. i have a feeling it would take quite a bit more of that white poly stuffing, volume-wise, to match acoustically. my Bose "interaudio 2000" bookshelfs use poly; they are good little speakers. never thought about fiberglass as a carcinogen, but it makes sense, same concept as asbestos. i have breathed in so much crap in my lifetime(NEVER wore PPE/respirators) it is quite frightening when i think about it
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby Geek » Sun Mar 17, 2013 10:05 pm

Fibreglass was used "in the day". I remember Radio Shack selling some overpriced R6 for the job.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby EWBrown » Mon Mar 18, 2013 7:35 am

If one prefers using itchy, scratchy fiberglass, (n) (n) (n) just buy a roll at the local Home Despot or Lowe's ;) (lol) =:o

The dacron polyfill (or aquarium filter material) is safer, not itchy, easy to handle. (y) (y) (y)

And, never use freshly sheared lambs wool, I've read tales of horror about the malodorous results of using that. (sick) (sick) (sick)

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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby Geek » Mon Mar 18, 2013 5:24 pm

Not to mention parasites =:o
(a lady I knew was into crafting from fresh sheared wool and she needed her house fumagated)
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby snitch56 » Sat Mar 23, 2013 11:50 am

Thanks for the suggestions. The insulation in these Altec speakers is just the standard “pink” 4-inch thick house insulation cut into 6”x6” pieces so substituting the polyfill will not be a problem. As zip mentioned the real Dynaco A-25’s have a dense formed precut sheets of fiberglass that fit perfectly in the speaker, it almost looks like they made this stuff with broken returnable soda bottles from the 70’s as the glass fibers are huge. Would acoustical foam be a replacement for this stuff? I also have a pair of faux A-25 that have that house type insulation in them.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby snitch56 » Thu Jun 27, 2013 2:08 pm

It has been a while but I finally finished these speakers. I ended up using 1 pound per speaker of that polyfill stuff and ditched the fiberglass. The polyfill was very pleasant to work with. Here are the other things I did:

1) Lightly sanded the walnut veneer
2) Applied around 10 coats of Howards restore a finish (Walnut)
3) Applied Formby’s Tung oil (around 4 coats)
4) Replaced xover caps with Dayton 5.1 uF film caps.
5) Replaced internal wiring with some leftover 16 gauge wire I had from making speaker cables.
6) Replaced binding posts with some Pomona 6883s.
7) The old CTS paper cone tweeters were real soft and worn, so I replaced them with some Goldwood GT-525 1” silk dome tweeters. The stock crossover point was at 2500Hz and I didn’t want to modify this. The GT-525 has an Fs of 1000Hz so they should be fine. I did have to slot out the mounting holes on the tweeters to make them fit.

So far I think the dome tweeter is an improvement over the old cones. They still need some listening time to break in.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby DeathRex » Thu Jun 27, 2013 6:38 pm

Why would you throw those speakers away? They look wonderful.

Yea the Advents I just got have 2 paper tweeters each, and they're not too good.

The insulation in the Advents is yellow foam 2" thick, cut to size. I've never seen foam inside speakers.
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Re: Speaker Fill- Polyfill vs. Old Fiberglass Fill

Postby snitch56 » Thu Jun 27, 2013 7:10 pm

DeathRex wrote:Why would you throw those speakers away? They look wonderful.


They were not that bad when on the curb, but they definitely needed some help. My initial inspection thought they were solid walnut but it turns out they are just really thick veneer. Cosmetically they turned out better than expected, there are no deep scratches or corner chips that are usually found on speakers of this vintage (+/- 1970 I think). These are the budget Altecs as the drivers are all CTS and not Altec.
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