Help with DIY ESL I just got

[mazur]

Hi.

This is my first foray into electrostatics. I got 3 diy electrostatics that belonged to a friend's dad. He built these speakers and I know nothing about them. I took some pictures and maybe you guys can help me. Here they are:

whole speaker

close-up of the panel

From my initial research here it looks like solid wire stators. Looks like each speaker has 5 separate panels mounted in a curved way. The panels are 38 inches long, 6 inches wide, addding to a total of 38x30 for the whole speaker.

There are 3 wires: one wire runs through the top and connects to the panels through small resistors. The other two, one runs through the front bottom of the panels and connects to the other through the panels and are tied to the frame by a screw (ground?). On 2 of the speakers the lower wires connect almost at the bottom, while the third, which he used as a center speaker, connects to the very bottom.

Questions:

- has anyone seen these before? what type of panels are these? any info would be great

- how do I go about connecting the speakers to the amp and bias?

- what quality of sound should I expect from these?

I appreciate any help.

Thanks
--
Elias

[frank ziel]

Hi,
can you post a picture from the bottom of the backside?
Is there no transformer?
Regards
Frank

[mazur]

Originally Posted by frank ziel

Hi,
can you post a picture from the bottom of the backside?
Is there no transformer?
Regards
Frank

Hi Frank.

No transformers. I can ask my friend to see if they are there some place, but I know they were cleaning the estate so it's probably gone by now.

I'll try to get a picture later today.

Thanks.
--
Elias

[godfrey]

I'd guess one wire connects to all the front stator wires (maybe thru resistors), the second wire connects to all the back stator wires (maybe thru resistors), and the third wire connects to the diaphragm(s).

The diaphragm needs to be connected to a high-voltage DC power supply. You can build this quite easily and cheaply if you don't have one.

The stators need to be driven by high-voltage audio. Normally a transformer's used to step up the voltage from your power-amp. The transformers are horribly expensive.

Plan B: If you have a push-pull valve amplifier, you can connect the stator wires from the speaker directly to the anodes of the output tubes in the amp. It won't go very loud like that, but hopefully enough so you can get a taste of the sound quality. Probably a good idea to connect a dummy load e.g. a 10 ohm resistor to the amp's normal output as well.

If you don't have a high-voltage supply for the diaphragm, just earth it so long. The valve amp will be putting a few hundred volts on the stators to give you some bias - not nearly enough, but hopefully enough for you to hear something. Then build a supply.

WARNING - There's high voltages everywhere inside valve amps and ESLs.
Seriously, this stuff wants to kill you. Be careful with whatever you do.

[geraldfryjr]

the design appears to be from the 1980 audio amateur book entitled "a high efficiant electrostatic loud speaker system".ther was also plans for a direct drive amplifier for them.jer

[mazur]

Originally Posted by geraldfryjr.

the design appears to be from the 1980 audio amateur book entitled "a high efficiant electrostatic loud speaker system".ther was also plans for a direct drive amplifier for them.jer

Hi.

Thanks for the reply. Would you know the author of the book? I'm trying to see if I can get it but haven't had luck with searching the title alone. Really appreciate.

Thanks.
--
Elias

[bolserst]

Originally Posted by mazur

Hi.

Thanks for the reply. Would you know the author of the book? I'm trying to see if I can get it but haven't had luck with searching the title alone. Really appreciate.

Thanks.
--
Elias

You can get a copy of the book containing Part 1 & 2 of the magazine article geraldfryjr mentioned "A high efficiant electrostatic loud speaker system" by David P. Hermeyer here:
BKAA1 - Audio Amateur Loudspeaker Projects