MadModder
Gallery, Projects and General => Project Logs => Topic started by: Andrew Wildman on October 10, 2015, 04:03:50 PM
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About 15 years ago I made some electrostatic loudspeakers. They have survived quite well but recently one of them gave up the ghost and took out the right channel of the bass and treble amp (I have an active crossover in the system and a separate stereo amp for sub, bass and tweeter). The amps should be easy to fix as they are quads and the output transistors always go first. The speakers should be easy as I made them but I am struggling to find anything wrong :doh:
The speakers existed (as far as I was concerned) before the wife, I don't think she would let me make these now as they are 6' tall :borg:
Here is an old pic of the speakers in our old house
(http://i1031.photobucket.com/albums/y373/dreeewman/speakers/10721.jpg)
Here is the gubbins inside the speaker, essentially a hv power supply and two big old step up transformers.
(http://i1031.photobucket.com/albums/y373/dreeewman/speakers/005.jpg)
Anyway better carry on measuring things to see if anything looks screwed up.....
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Problem is obvious. In the first picture they are lying on their side, as is the rest of the room, :scratch: :scratch:
Now you have them upright, so obviously gravity is affecting the electrons :lol:
(In case it doesn't show in your browser the first picture is rotated 90 degrees)
Later edit : ..ello ..ello they're back upright again :scratch:
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Assume you have done the obvious swap over the L R output from pre amp non working side, take it from there.
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Hmm they look a bit like martin Logan's :-)
Ah you said quads , 405s? If so, they can self destruct if the o/p gets (thyristor protected output to protect their speakers)
Sounds like a flash over. What bias volts are you running?
Bill
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Well after a bit of fiddling one of the plates to the membrane is measuring about 6 Meg ohms but only at hv. Should be hundreds of Meg. At multimeter voltages it shows open circuit. Indicates that there is something like a cremated harvest mite in there! Time for a rebuild.
Bill the bias voltage is about 6 kV. I am running a 405 for the bass and a 306 (I think) for the treble. When I first got the 405 I had to repair it.
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hi if I had that much mess on the living room floor I wood come home from work and find the lot in the bin good work :nrocks:
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I'd like to see that much of my carpet!
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Brill