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Old 23rd November 2012, 07:13 PM   #1
Gwho is offline Gwho  United States
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Default Need Help With Electrostatic Speaker Repair

I was wondering if it is possible to repair an electrostatic speaker and what options I may have. The electrostatic speaker I have is a Soundlab B-1S. It is a stereo subwoofer that has a left and right panel for generating low frequency sounds below 350Hz. The panel is about 80"x48".

The problem that I have is the insulation is breaking down on the stator wiring. I've gotten a couple of major electrical shocks moving my hand near the front of the cloth of the speaker. There is minimal sound coming out of the speaker and increasing the volume to the speaker does not yield any volume increase coming out of the speaker.

I had the mylar replaced at the factory and the backplate was also checked out (e.g. both are working great). They did test the panel before shipping it back to me. I was told that it was working fine. The problem lies with the stator wiring. This speaker is from the mid 1980s so it is pretty old. They told me that the insulation they had at the time was prone to breaking down with age.

I do not have the money to replace the panel. I am looking for a low cost way to repair the speaker as it has new mylar. Do I have any options?
I do not know a lot about electrostatic speakers so I am looking for any experts out there that might know how Soundlab Electrostatic speakers are made.

Is it possible to replace the stator wiring?
Can the insulation be repaired? If repaired will it continue to fail in other areas of the stator. Is this a diy job for a novice.

Any thoughts would be appreciated.
Thanks in advance for your input.
Regards,
gwho
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Old 23rd November 2012, 11:12 PM   #2
Bazukaz is offline Bazukaz  Lithuania
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Hi,

I think it is possible to repair isolated spots on the wires but don't expect that you can just spray it down with something and will be perfect again.

But from your description its not completely clear(and even does not look like) the problem is insulation.
If the insulation did break down then it should sound more or less ok to a certain level and then start to arc, although I am not familiar with that design. When there is no output in the panel I would first check other things:
1) If membrane is charged properly(can be problem with wiring, conductive coating on it, charge leaking somewhere etc).
2) Too low tension or too thin membrane and is struck to a stator from electrostatic force
3) some other things I missed, thats also common with ESLs

Is the panel designed to be disassembled? You could then investigate step by step.
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Old 23rd November 2012, 11:30 PM   #3
Gwho is offline Gwho  United States
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The speaker was just reskinned with new px mylar. The backplate was also checked. I did check a number of checks and the conclusion from soundlab was the stator is bad. They must be able to be disassembled to some extent.
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Old 24th November 2012, 02:07 PM   #4
Gwho is offline Gwho  United States
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Bazukaz,

Your help is greatly appreciated.
Here are the tests we performed.
1. I can adjust the bias with the backplate connected to the B1S. Turning the bias way up creates a continuous sizzling or crackling sound that indicates that the backplate is functioning correctly.
2. A low level sound comes out of the B1S when an amplifier is connected to the speaker. Adjusting the volume on the preamp does not change the volume coming out of the speaker.
3. I took the backplate out of the B1S and tried it on another speaker (A-1) Both channels of the backplate were tried in the different speaker and it was able to bias the speaker properly. Adjusting the volume on the preamp produced a corresponding volume change at the speaker. Obviously, the sound coming out of the speaker was relegated to the lower frequency range (below 350Hz) but is sounded fine.
4. As I mentioned I got shocked a couple of times as I put my hand in front of the speaker cloth on the front side of the speaker.
5. The speaker was disassembled at the factory to put in new mylar. I assume they did this correctly but I get your point that if they didn't the membrane could get stuck.
6. One thing I would like to point out is that I did have to change the bias circuit shortly after receiving the unit back. The bias circuit failed but was working when I received the unit back from the factory. Perhaps there is an issue with the wiring that caused the bias circuit to burn out or would bad insulation do the same thing?

Regards
Gary

Regards,
Gary
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Old 24th November 2012, 02:08 PM   #5
Gwho is offline Gwho  United States
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I would appreciate it if a member familiar to these speakers could tell me how it is contructed.

Regards,
Gwho
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