Speaker repair help?

[shakti]

I have a couple of '69 G12Hs with voice coil rub. I won't go into details, but a certain douchebag seller sent them to me as perfect, even though I specifically asked about voice coil rub. When I unpackaged them, it was obvious that two out of three had a significant rub. They sound and measure fine apart from the rub, which is very obvious with clean sounds.

I've fixed voice coil rub before on an Altec 417C, by shimming the voice coil and applying acetone to the spider. One of the speakers appear to be fixable with this method - there's no rub after a few rounds with acetone, except there's occasional rub which seems to stem from debris in the voice coil gap, probably little particles of glue residue from where the dustcap was removed. The old glue has gone extremely brittle. But it looks like this speaker is salvageable with this method, and hopefully I can clear the voice coil gap properly before attaching a new dustcap.

The other speaker is more problematic...even after a few rounds of acetone, there is a rub...but again I'm pretty sure the problem is debris in the voice coil gap, as the rub is not very consistent, and sometimes *very* loud on manual palpation. Sounds like something caught between the magnet and the metal part of the voice coil, which indicates that there may be debris in the outer voice coil gap. This is where the real fun begins...how to clear the outer voice coil gap of debris? I suspect the only way is to completely remove the cone assembly from the frame. Actually, I got so aggressive with the acetone that the glue to the spider already loosened, so the whole spider is now loose. But I still need to get the edge of the cone and the gasket loose from the frame.

Before I proceed, can anyone give me any tips on how to properly fix the speaker? If I lived in the US I would send it to Chris M for repair, but shipping costs would be way too high.

My biggest concern right now is to get the edge of the cone loose from the frame. Any hints/suggestions? Should I try to remove the gasket first, then the cone edge? Or better to get the cone off with the gasket in place? Which type of glue was used on these ('69 era) Celestions? Does it help to apply acetone, or might it be better to heat the join with a hair dryer or similar? Any help is greatly appreciated!

[BaronGreenback]

If you send them to me (UK) I should be able to sort them out for you. PM me. I wouldnt advise anyone to remove at the outer edge as there is a big risk you will tear the cone and ruin the speaker.

The original dust cap can usually be saved and re-used if removed properly.

i would ask the douchebag seller for a hefty refund too. not as described etc.

[Scumback Speakers]

I've got a couple of old G12H20 8 ohm 30w (T1234, mid 73 models) speakers a client sent to me to try and save. One of them "maybe" can be salvaged. The spider on one speaker was completely loose and had chips out of the edges it had deteriorated so badly. That one is toast.

The other one I've reglued the spider down and gotten the debris out of the voice coil gap, but it's still got a chunk of glue or something in there I can't see. It also has a large chunk of glue overhanging the voice coil itself. It looks like someone got frisky with the glue at Celestion that day in 73. It only makes a rattling/farting noise from around 90-175 hz, then it's fine (after fixing the spider and getting the crap out of the voice coil gap) on the waveform generator. But I'm sure it's going to make a noise when playing notes on the low E & A string, which would be a deal killer.

Acetone will work to release the glue in most cases but you have to be really careful as it weakens that old glue and might affect the paper/spider fibers if you use too much. Been there and done that with the "acetone aging" treatment that Matchless used to do years ago.

Sorry Shakti!

[shakti]

I tried talking to the douchebag seller...there's a reason I still call him a douchebag.

Thanks for your offer, Baron...still, shipping costs are probably fairly high to and from the UK, so if I can sort it out on my own I would prefer that. I think the biggest problem right now is cleaning the voice coil gap properly. But how to do that if there's debris in the outer gap??

If all else fails I'll consider shipping to you, will check on the costs.

[shakti]

I talked to Chris M and got some invaluable advice. I'll be making some more attempts to save it without removing the cone entirely. Too many things that could go wrong, and there's nothing wrong with the surround.

One more question: does anyone think it's possible to lift the voice coil entirely out of the gap while the cone is still attached to the edge of the frame? As I said, the spider is now loose, so I can lift the cone quite a long way, but I'm curious if it's possible to lift it all the way out, thus enabling me to gain access to the whole voice coil gap and cleaning it, slowly and bit by bit. I can get close to lifting the whole voice coil out, but I'm afraid to go any further as it puts stress on the edge of the cone.

The good news is that one of the speakers now appear to be fixed with the traditional shimming/acetone treatment! Just need to test it and attach a new dustcap!

[Scumback Speakers]

I think you're going to have a lot of trouble doing that, sir. I just got two old pre rolas in, and one of them had a chunk of something in the gap from the spider coming loose. I had to cut off the dust cap, re-shim and clean the gap and it was good to go with a new dust cap.

The other one had a disintegrated spider. I tried everything I could to lift the cone and voice coil up enough to fit a new spider on there but I just couldn't get the proper clearance without the cone getting strained.

I finally just gave up and reconed the entire speaker. So the client has one fixed T1234 8 ohm G12H30 and one that's been reconed with the PVC cone/paper voice coil, etc.

[whopperplate]

What about realignment via shimming with application of a heat gun? I have had great success using this method as far as fixing vc rub.

[shakti]

Where do you put the heat gun?

[whopperplate]

Heat the spider and voice coil while it is shimmed in place then let it cool down and settle to the shape and form. Have salvaged a few speakers this way that rubbed.

[shakti]

Interesting...I'd be wary of applying too much heat though, and wary of drying out the spider in particular. But acetone does seem to dry things out as well, so it might be worth a shot. I'll reglue the spider with the voice coil shimmed first, if it still rubs I might give the heat gun a try.

[whopperplate]

You don't need to cook the speaker, just a minute or two will work. I have never had any issue with the parts drying out, but with vintage speakers the chances obviously would be greater with the old adhesives and lightweight materials. I would imagine acetone to be far more potentially detrimental when over applied.