bdp24, I wouldn't say "serious" problems but it was a compromise I did not have to make. Jim Strickland of Acoustat and Roger West of soundlabs were/are both determined to make 1 way full range electrostatic speakers. The problem is that it is virtually impossible to maintain reasonable flat frequency response with one transformer. Jim Strickland weaseled his way around his problem by using two transformers and a crossover of sorts a solution eventually borrowed by Sound Labs. Because I do not expect the speaker to do anything under 100 Hz and I can equalize any response error I can easily get away with using just one transformer straight up.
The problem with the high voltage amps is that it is very difficult for them to develop the sort of power you need to drive the speakers with gusto even after having removed 100 Hz down. People tend to think that ESL are fragile and lack dynamic impact. Not if you drive them correctly! They will hit as hard as any horn albeit requiring a lot more power to do it. The horn and the ESL are the best impedance match to air. They just go about it in different ways. The result in terms of impact and transient response is the same but because you can use big magnets on horns they are a lot more efficient. The problem for ESLs is that there is a limit to the bias voltage you can use before you start to arc out. You could get them just as efficient if you could get the bias voltage up to say 10,000 volts but at a relative humidity of 50% they start arcing out at 4000 volts,
.Some are limited to 3000 volts.
