Howdy folks. I have a potentially stupid question because I'm trying to build a solid state energiser.
I can see this going to the DIY subforum soon, but I post it here so the headphone gurus can see it, and hopefully comment.
Electrostatic headphones have the diaphragm biased to say 580V. Then the perforated plates on either side of the diaphragm are driven with out of phase signals of say +/-200V peaks. So when one plate pushes the diaphragm away due to more similar charge, the other pulls it closer due to more opposite charge. This I understand.
Why doesn't anyone bias the plates to +580V and -580V, and drive the diaphragm with +/- 200V peaks? Surely the electrostatic forces involved would be the same? And the single ended amp is much simpler to make.
I can think of 4 issues that make driving the diaphragm the less good idea:
1) It may just be a case of it being less unnerving to have 200V next to one's ear than having 580V there? It shouldn't be a safety issue as the high voltage biasing is done via very large resistances.
2) With +/-580V bias one has to prevent leakage at 1160V between the plates, rather than 780V at peaks between plate and diaphragm. So about 50% extra voltage. But leakage is a b*tch anyway.
3) One benefit of differential (balanced) drive on the plates is the cancellation of even harmonics. But as harmonics go those are actually the less unpleasant ones.
4) Compatibility with the wiring of the Stax headphones. One would need to rewire the unobtanium plug if using those. The diaphragms of the Pro type share a pin for bias. Not impossible but nobody likes the idea of going in there.
Seeing as I haven't even started making the headphones yet :-D are there any more reasons that make it a stupid idea to bias the plates + and - and only drive the diaphragm?
I can see this going to the DIY subforum soon, but I post it here so the headphone gurus can see it, and hopefully comment.
Electrostatic headphones have the diaphragm biased to say 580V. Then the perforated plates on either side of the diaphragm are driven with out of phase signals of say +/-200V peaks. So when one plate pushes the diaphragm away due to more similar charge, the other pulls it closer due to more opposite charge. This I understand.
Why doesn't anyone bias the plates to +580V and -580V, and drive the diaphragm with +/- 200V peaks? Surely the electrostatic forces involved would be the same? And the single ended amp is much simpler to make.
I can think of 4 issues that make driving the diaphragm the less good idea:
1) It may just be a case of it being less unnerving to have 200V next to one's ear than having 580V there? It shouldn't be a safety issue as the high voltage biasing is done via very large resistances.
2) With +/-580V bias one has to prevent leakage at 1160V between the plates, rather than 780V at peaks between plate and diaphragm. So about 50% extra voltage. But leakage is a b*tch anyway.
3) One benefit of differential (balanced) drive on the plates is the cancellation of even harmonics. But as harmonics go those are actually the less unpleasant ones.
4) Compatibility with the wiring of the Stax headphones. One would need to rewire the unobtanium plug if using those. The diaphragms of the Pro type share a pin for bias. Not impossible but nobody likes the idea of going in there.
Seeing as I haven't even started making the headphones yet :-D are there any more reasons that make it a stupid idea to bias the plates + and - and only drive the diaphragm?
