Posted by CV on November 12, 2003 at 08:28:16:
In Reply to: Real World ESL Direct Drive Amplifiers......? Acoustat posted by Bob Ratner on November 12, 2003 at 08:09:18:
Hi Bob,
I think you must have me confused with someone else - I don't have any pictures up. In fact, I'm sorry to say I've never even heard a Soundlab speaker (probably just as well given the state of the wallet).
4nF is a tricky load - Z of around 2k ohms at 20kHz.
Thankfully, ESLs have a rising response on axis, so you could probably whack a large resistance in series with the panels to form a first-order treble rolloff and ease the load on the amp.
Tricky to say what current you'd need to avoid slewing with real music, but I'd think that with almost 6kV peak per side at 4nF, one would want to be able to deliver a good few hundred mA per side in a push-pull arrangement.
Realistically, would be looking at heavy excursions into class B.
A conventional power supply could be done, but it would weight a few hundred pounds! Switching amp as you suggest would be the way to go.
Hmmm, just wondering if a switching amp is the way to go... think a stepped up DSD stream...
Hope this helps.
Best,
Chris