ESL safety protection.

[M Gregg]

Just a quick question,

The stator of the ESL is powder coated or painted.
How do you ensure no contact with the stator voltage?
The two outer plates are at B+, are we just relying on the powder coat?


Regards
M. Gregg

[geraldfryjr]

Yes ,unless you build a frame and supports for a protective insulating screen of some sort. jer

[M Gregg]

Originally Posted by geraldfryjr

Yes ,unless you build a frame and supports for a protective insulating screen of some sort. jer

Is this also the case with ESL like martin logans? IE do they rely on the powder coat? I guess an isolation Tx for the B+ may help?

Regards
M. Gregg

[geraldfryjr]

The last time I saw one up close I don't recall seeing any extra type of external protection system although I did not risk touching the stator with the my hands flat on each stator while they were operating to find out either.

I have touched mine with the the bias supply on before only when there was a leakage did I get zapped.

I have accidently touched a bare wire feeding my panels A few times and got zapped pretty good.
But this is not a practice that I would recommend by any means.

I hope that helps. jer

[oshifis]

Originally Posted by M Gregg

Just a quick question,

The stator of the ESL is powder coated or painted.
How do you ensure no contact with the stator voltage?
The two outer plates are at B+, are we just relying on the powder coat?


Regards
M. Gregg

Are you talking about the Quad ESL (aka ESL-57, although Quad themselves never used this designation)? The stator is driven push-pull by the input transformer with GND reference, and the diaphragm is at HT, not the way around. I think other electrostatic loudspeakers operate on the same principle.

[kavermei]

Hi,

Only when the speaker is driven by a so-called direct-drive amplifier, would there be a DC voltage on the stators. That's about 1% of the products out there, and here is a real danger if the stator insulation is damaged.

In the other 99%, there will be no DC voltage on the stators. Still, unless you trust the insulation, you shouldn't touch one stator with the right hand and the other with the left while music is playing.

Kenneth

[M Gregg]

Thank's for the answers,

Just a quick question is the performance effected if the holes in the stator are square and not round?
I ask because it seems the steel plates with square holes have a higher percentage of air to metal. IE more holes to the inch.

Regards
M. Gregg

[Calvin]

Hi,

Only when the speaker is driven by a so-called direct-drive amplifier, would there be a DC voltage on the stators.

This can be true, but in some cases it is not. Either a DC-blocking cap in the amp´s output or dual supplies are a measure against DC-potential on the stators. The Acoustat used a DC-blocking cap for example.

jauu
Calvin

[kavermei]

Hi Calvin,

I wouldn't consider cap-coupled to be direct drive any more than transformer coupled... You are right about the case where you have dual supplies, of course.

Kenneth