Segmented ESL Tweeter --> less voltage need for OTL

[Quongelvis]

Hi

i have read some stuff about OTL amps and it seems to be a very complicated and dangerous way to go.
But what if only a 100pf surface for the Highs should be driven?
I have made some voltage measurements, tweeter segment driven Fullrange
with pink noise at very loud sound level the voltage on the secondary of the
transormer did not exceed 200volts, applying the Highpass (6 dB at 13 kHz)
did not exceed 20 Volts on the secondary.
Using a 13 khz Sinewave as loud as possible measured around 200 Volts, too.

My conclusion is now that for this application something <= 200 Volts should be enough to drive the tweeter-segment
Is this a donky thougt or possibly a way to go for the heighs?

Maybe something an esl headphone amp could do that?


have anice day

Carsten

 

[bolserst]

hmmmm....200 volts sounds quite low.
How did you measure the voltage? and what ESL were you measuring?

 

[Quongelvis]

i used a simple multimeter on the secondary side of the transformer.
Maybe this is not very accurate but should give a hint about the Region of voltage. I am using a german Capaciti Panel 800pf, the tweeter Segment has aroud 100 pf.
I have seen the schackman otl amps, they use 440 Volts for F < 800 Hz or 900 Volts
for F > 300 Hz.
Her is a sheme of the 900 Volt Version (scroll down).
http://shackman-electrostatic-loudspeakers.reromanus.net/V-Typ-WR.pdf
I don't want to mess around with 900 Volts, but did never try anyone to drive the tweeter with low voltages around 200 Volts?

 

[bolserst]

You might check your multimeter reading on a known signal amplitude for different frequencies. The AC response of most multimeters drops off at higher frequencies. For example, my Fluke 77 reads 1.00 for a 1Vrms signal at 100Hz, but only 0.16 at 10Khz.

When Capaciti posted to this forum, all of his panels were segmented designs where the central segment received the same voltage as all the other sections of the panel. Is this what you are calling the tweeter segment?

 

[Quongelvis]

yes, now i think the measurements were not accurate.
Its the central Segment that i call the tweeter segment.
I will highpass this segment 6dB at 16 Khz, odd frequency
but that matches sonically for me ic i lowpass the midsegment at 7 kHz / 6dB

Can anyone tell me a number how much voltage would i need for the highpassed panel?
Or am i completely wrong and the highpass doesn't affect the voltage need and the still needs the same voltage?