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 Post subject: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 2:44 pm 
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Joined: Feb Wed 17, 2016 6:51 pm
Posts: 73
I would like to remove the cone and spider of a 1950s Jensen speaker, and I am curious if any of the members here know what types of adhesive were used when new, and what would be the most suitable solvents? I would like to preserve the cone, the voice coil is beyond repair though.


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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 3:40 pm 
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Joined: Aug Fri 12, 2016 1:49 am
Posts: 313
Location: Houston, TX
It's a paper cone, right? The solvent is gonna be a liquid. Paper and liquids (even fast evap) don't get along well. Compound this with the idea that the older the paper, the more fragile, and solvents are harsh to begin with.

I think your chances of not damaging the cone are low.

But then, I don't recone/repair speakers for a living, so take that 2 cents for what it's worth. :)


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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 3:45 pm 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 818
Location: Austin, Texas
I've used acetone to dissolve speaker glue without damaging the cone. It works well for softening the glue to recenter a warped cone.

Jay


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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 3:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12904
Location: S. Dartmouth MA 02748-1225 USA
The solvent will be acetone, if the bond is stubborn, then move to toluene. Do not soak the entire speaker, unnecessary and the fumes will be overpowering.

The solvents are managed with disposable polyethylene eyedroppers, either laboratory grade or China economy will work. The lab grade can be modified for a very tiny dispensing nozzle by pulling the nozzle with pliers, it will stretch and thin out, snip the crushed end to reopen.

Other solvents also work but they are harder to get, dangerous to use and/or extremely flammable :shock:

These are the eyedroppers I use:

Attachment:
100-Pack 0.2ML Disposable Eye Dropper Transfer Graduated Pipettes.jpg
100-Pack 0.2ML Disposable Eye Dropper Transfer Graduated Pipettes.jpg [ 11.51 KiB | Viewed 107 times ]


https://www.amazon.com/Disposable-Dropp ... B01C42BFVY

Apply solvent to the bond line and continue to apply until the bond gives way with a slight pull.

I make assembly jigs of MDF, PVC pipe and large dowels. The jig keeps the surround/cone aligned to the voice coil former so they remain perpendicular during adhesive cure. I highly recommend using G-C speaker cement, it's solvent is toluene.

All is off if someone has used modern super-glue or urethane adhesive.

Oh, the same eyedropper is used to apply the G-C adhesive in a thin line.

I re-cone for fun...

Re-post if you need other re-cone tips on vintage speakers...

YMMV

Chas

_________________
First they ignore you, then they laugh at you, then they fight you, then you win.
"Gandhi"


Last edited by Chas on Nov Fri 09, 2018 4:09 pm, edited 2 times in total.

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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 4:06 pm 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 23813
Location: Annapolis, MD
How about the bond between cone and voice coil? The last time I assembled a speaker, I used epoxy. I don't know if that was the norm in the 50s or 60s.

_________________
-Mark http://pixellany.com

"It's always something". --Gilda Radner (1946 - 1989)


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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 6:31 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 4777
Location: Near Brandon, Iowa
I've used acetone to melt the adhesive. It's important to apply just enough to do the job... too much and the solvent can carry some of the dissolved adhesive to the voice coil channel where it will dry and interfere with voice coil movement. A small artist's brush (natural bristles) works well for this purpose.


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 Post subject: Re: Speaker Rebuilding Solvents?
PostPosted: Nov Fri 09, 2018 8:48 pm 
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Joined: Sep Tue 15, 2015 1:16 am
Posts: 263
Location: 18424 PA
If the cone near the edge folds isn't perfect and at all dry rotted, you will blow it out when you use it. There are many places that will rebuild a Jensen, and do it properly. I have never heard of changing a voice coil and leaving the original cone intact, good luck on that. Try Weber for the speaker repair.


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