Glad to join the party

[statcat]

Hello all,

What a happy accident to have found this forum. I was looking for help on restoring my much loved, but ailing, Acoustat Model 3's and discovered what appears to be geek heaven!

By way of introduction, I am an artist who, in an earlier time, was able to afford some wonderful audio equipment that is now aging and I cannot afford to replace. I have had the Acoustat's for over 28 years and have come to love the exquisite detail they reproduce.

Actually only one of the speakers is performing poorly. It's sound is thin and lacking bass response compared to the other. It's been like this for some time. but because there is no longer a dealer near here, I've just been living with the problem.

Given this limited description, does anyone have any suggestions as to what the problem might be and how to solve it. I should say that I'm very adept mechanichally, but electrics are not my forte.

Looking forward to being a part of all of this, James

[EC8010]

Welcome to the forum. It sounds as though the diaphragm isn't being charged. To test that would need some very careful measuring of the 5kV supply. Not an ideal start for someone who doesn't know much about electricity. Perhaps you know someone with a little more knowledge?

[statcat]

Thank you very much for your prompt reply,

Silly me! I just realized what the problem may be. I have that speaker plugged into a power bar that I switch off at night, which I now realize would cause havoc with the charging of the diaphragm. I believe that there may have been quite a few instances of running the speaker without power to it at all. Is there a chance that permanent damage has occured because of this?

Once I have corrected this oversight. will the diaphragm charging problem take care of itself? If so, how long should this take?

Your assistance is much appreciated.
J.

[EC8010]

I would think it unlikely that you've damaged your loudspeaker by operating it without any bias. When I made electrostatic headphones, they tended to take about half an hour to fully charge, if your loudspeakers take longer then they either have a fault or you're trying to use them in a damp environment.

You can probably get better answers than mine by asking in the ESLs (ElectroStatic Loudspeaker) section of the forum.

[Cal Weldon]

Hello and welcome to the forums.

[statcat]

Originally posted by EC8010
Welcome to the forum. It sounds as though the diaphragm isn't being charged. To test that would need some very careful measuring of the 5kV supply. Not an ideal start for someone who doesn't know much about electricity. Perhaps you know someone with a little more knowledge?

Success at last! And I must say that your above assessment was a key clue to the problem. Let me explain.

After I determined that the supply of electrical power to the speaker was not the problem, I assumed the worst and suspected that speaker interface was damaged. To confirm that, I swapped interfaces with the other speaker, which has been working perfectly all along. You can imagine my surprise when I powered up the system and that change had made absolutely no difference whatsoever!

That left only the speaker panel as the source of the fault. Eventhough I am not skilled in electrics, I felt that looking for a bad connection was at least worth a try.

I completely removed each panel and visually checked every connection. Everything appeared to be un-damaged and in good shape for a 28 year old speaker. I then had an "Ah-Ha!" moment when I discovered one of the bias-supply wires wrapped with a bit of electrician's tape. I slid back the tape and sure enough, a damaged length of wire appeared (I hadn't noticed this before because it had been pushed back into the speaker body--someone hiding theirs sins, no doubt).

This stroke of luck seemed too good to be true, as only the insulation appeared to be damaged (looked like it had been touched by a soldering iron); the wire itself seemed to be okay. I kept looking. Another bias-supply wire (there are 3) seemed to have a poor solder connection to the plug into the interface board. I wiggled it just a bit and voila! It broke. Finally the diaphragm power thief been apprehended!

I removed the offending length of wire and re-soldered the 3 bias-supply wires to the interface plug. Re-assembly quickly followed.

With much trepidation, I fired up the system, still not believing that the fix could be this simple (especially after having lived with the reduced output problem for over 10 years because I assumed the repair was beyond my capabilities).

Because of the charge time required for full operation, my initial listening did not fill me with much hope. The repaired speaker did sound better, but not by much. After about a half-hour or so I began to notice a definite improvement. After about two hours the sound was fabulous, and I was in bliss (you might even say that I was "electro-ecstatic!")

I want to again thank you for your insightful contribution. You have helped more than you will ever know.

[EC8010]

I'm overwhelmed by your politesse and so glad you've been able to fix your loudspeaker. Sadly, things don't always go as well as that, but it's so nice when they do.