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 Post subject: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 8:07 pm 
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Several months ago I noticed buzzing, rattling, and distortion from the left channel of our stereo. My first thought was that one channel of the amp was going bad. Then I noticed these noises from both speakers. Pulling the cover off, I could see that the foam surrounds that secure the cones to the frames were disintegrating.

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I purchased these Cerwin Vega ATW-12 speakers in 1992 or early 1993. Although I wouldn't consider them "vintage hi-fi" yet, this thread might be useful for anyone contemplating replacing the foam on a set of speakers. It saved me from buying a new set of speakers.

There are several vendors that sell foam replacement kits. I bought mine from Simply Speakers. The kit comes with instructions and a tube of speaker glue. And they have excellent You Tube video tutorials for several brands of speakers, including the 12" Cerwin Vegas.

Excluding glue drying time, it takes about an hour to do one speaker. Here are the main steps:

1. Remove speaker from cabinet
2. Remove gasket and clean off old foam
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3. Clean old foam from frame

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4. Clean old foam from cone
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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 8:15 pm 
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5. Glue New Foam to Cone
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I used a white pencil to draw a line around the old glue edge to help align the new foam
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Let glue dry for an hour before proceeding to the next step.

6. Glue New Foam to Frame
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Make sure the cone is not scraping against the voice coil, then glue the outer edge to frame
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Allow glue to dry for an hour.

7. Re-install Gasket and Glue to Frame
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Flip speaker over and let glue dry for an hour.

8. Replace Speaker in Cabinet
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There are excellent You Tube videos with much more detail than I have shown here. With the Simply Speaker refoam kit, it is not necessary to remove the dust cap and shim the cone around the voice coil. If the instructions are followed, the new foam will self-center the cone.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 8:37 pm 
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Thanks for sharing the great tutorial.

I knew these kits were out there, but have not had the occasion to try one.

I wonder if the new foam surround materials are any more durable than the old ones, or is this just the nature of the material?

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 9:54 pm 
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I wondered the same thing. The originals lasted 28 years. If the replacements last that long, I won’t be around to do the next set.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 10:02 pm 
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I have several Bang & Olufsen CX-50 speakers with rotten foam. I have started to replace the foam but got sidetracked. I have the parts, just gotta get off of that fat....

Thanks for the inspiration...

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 10:20 pm 
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Nice job Ed.

I just did my vintage 1992 Sony speakers a month ago. They came out pretty good, but one speaker has distortion in it, but that distortion was there before the foam rotted (yeah, these speakers sat in my storage for 18 years). I have to take a look at the crossover network when I get a chance.

Image

After:

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 11:21 pm 
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Thanks, Scott. Your Sony speakers look great. If you swap the speakers, does the distortion follow?

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 11:42 pm 
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Did a pair of Bose 901's, 18 speakers total. Found the Westmalle beer glass fit the outer ring perfectly.
These have a low voltage battery used to center the cone. Set up a production system, center foam
was a plastic dish that fit the profile with a heavy weight on it.


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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Fri 27, 2020 11:54 pm 
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Location: 18424 PA
If the spider is holding the voice coil centered perfectly it will work. I have a pair of old Altecs i need to refoam here but have too many other projects first.


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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 3:24 am 
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I used the refoaming kit from Simply Speakers to do the midrange drivers on my big Jensen 6 speakers, and they turned out very well. A tip, however; wear old clothes! The glue that they supply is very good, and permanent.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 4:20 am 
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I should note that the images above might give the impression that scraping the old foam off the frame and cone is hard work, but it's not. Soak the old foam residue with alcohol and it comes right off.

I used acetone on the metal frame as alcohol is hard to come by at the present time, but I used alcohol on the cone as I didn't know if acetone would damage the cone paper. Cleaning up the gasket is actually the hardest part of the job.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 12:46 pm 
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Tim Tress wrote:
I used the refoaming kit from Simply Speakers to do the midrange drivers on my big Jensen 6 speakers, and they turned out very well. A tip, however; wear old clothes! The glue that they supply is very good, and permanent.


No precision gluing huh, all over your clothes? Did the speakers survive the glue deluge ? Did you use a sprayer? I'm confuses
how the glue got all over. I used a q-tip and placed the glue right on the surface and virtually no mess.
What is your technique, not that I want to use it, I want avoid it.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 12:59 pm 
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Ed Morris wrote:
Thanks, Scott. Your Sony speakers look great. If you swap the speakers, does the distortion follow?

That was the first thing I checked. Not the channel. I am hoping that it is something in the crossover network. A couple of electrolytics there. It is on my "to do" list. I did remove the dust cap and shim the voice coil. The kit came with new dust caps and shims. Voice coil moves smoothly.


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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 1:41 pm 
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No mess; just a little on the fingers. I just wanted to add a !little cautionary advice! One has to be careful with the glue.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 1:51 pm 
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In another thread, The Rabbit mentioned using flexible rubber replacement surrounds. Are those generally available from the same sources in the same sizes as the foam surrounds?

I should probably just PM Dutch Rabbit...

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 5:06 pm 
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did you and i coordinate schedules ?

8)

this was today's project.

I got a minty pair of Realistic Nova 15 speakers for 5 bucks last winter. they were sitting in the shop for this summer's refoam project.

today, I removed the old foam and OCD allowed me to remove all the old foam and glue down to the bare metal basket.

what a job between a can of lacquer, 5 razor blades, and some fine grit sand paper, they are clean as a whistle.

I plan to put new Rubber surrounds that will last a lifetime on them very soon.

I plan to install a REAL crossover that will cross them at 3k using a second order 12dB / octave slope. they have the woofer wide open now and a pathetic little single capacitor on the tweeter from the factory.

I have LOTS of time.

I have a total of 8 Realistic Mach Two and Threes to install my second set of foams on too, their third set including the factory foam. I bought them back in the 80s when I was a teenager, refoamed them in 2001 and they need it again.

steve


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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 5:38 pm 
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Interesting! The Cerwin Vegas I just refoamed replaced my set of Realistic Nova 15's that I bought in the 1980's. As I recall they were pretty good speakers and I had them hooked up to a Panasonic RA-6600 that I still have and use occasionally. I bought the Cerwin Vegas when I bought a Harmon-Kardon audio/video stereo receiver that could play tapes and dvd's with surround sound.

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 5:49 pm 
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https://www.simplyspeakers.com/search.html?k=rubber

this is NOT for the faint hearted. when the rubber surrounds are placed on the bead of glue, they can start to react and curl. i did a pair of rubbers about 10 years ago.

i must call simply speakers and see if they are using a new glue that will not cause the rubber surrounds to "curl" when they hit the glue.

they work and are done well, but it does not look good.

steve

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 5:51 pm 
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Ed Morris wrote:
Interesting! The Cerwin Vegas I just refoamed replaced my set of Realistic Nova 15's that I bought in the 1980's. As I recall they were pretty good speakers and I had them hooked up to a Panasonic RA-6600 that I still have and use occasionally. I bought the Cerwin Vegas when I bought a Harmon-Kardon audio/video stereo receiver that could play tapes and dvd's with surround sound.

maybe mine are the Nova 16 model...either 15 or 16.

i got the pair for a few bucks last winter and this was to be my summer project.

i have 8 mach twos/threes to do this summer with their third set of foam--original factory foam, my refoam in early y2k, and the one i am about to do in 2020.

steve

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 Post subject: Re: Replacing Disintegrating Speaker Foam
PostPosted: Mar Sat 28, 2020 6:20 pm 
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I did not have any curling problems with the Simply Speakers glue. It appears to be a contact cement, probably solvent based. It takes a few seconds before the glue starts to adhere, and during that time, it's important to keep running your fingers around the top of the foam edge that you are gluing. Once you feel that the glue is grabbing, you can let up some, but I kept doing it until I could see there was no separation between the foam and the cone or the frame.

In the photo below, both edges have been glued, and I'm pushing down in the center checking for any rubbing. You can see the edges are smooth, with no curling.

Attachment:
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