OK, I just have to vent here.
Electrostatic loudspeakers present a very low (often below 2 ohm) load at high frequency. And it is essentially capacitive, so is a challenge for many amplifiers.
With all due respect, that is just more of Sander's nonsense.
The load seen by a traditional amp in an electrostatic speaker is the primary winding of the step up transformer, an inductive
load, and the current drawn is based soley on the impedence of that primary winding. a secondary having no load beyond the capacitance of the speaker has a negligable effect on the primary impedence - Sanders "high current" design is just stupid.
I have also met with Sanders and followed his "career" from the moment he got the idea to build his first speaker from Dave Heremeyer's project.
In fact, Heremeyer was working on his second system and offered to help Sanders - who clearly knew nothing about ESL's.
How did Sanders repay this generosity?
By stealing Dave's designs, and then trashing Dave's first design as clearly inferior to "his own".
I'll give you just one example of just how clueless Sanders really is - and there are many.
The conductive diaphram coating of an ESL needs to be of high resistance to assure the driver operates in charge mode. This is just a simple fact, and has been since Walker first started work on the quads.
This charge mode increases the slew rate dramatically because it lowers the current nesessary to charge the diaphram fully in order to respond to the plates.
Yet as Sanders published "I don't even measure it anymore, I just rub it on till it sticks"
So how then did he then determine what current range he needed - not knowing what his load would be?
By playing music and watching a scope for clipping!
That, my friends, is absolutely ridiculous - you can't "see" this current clipping on a scope, the output signal is still there, the diaphram just fails to respond accurately because it's unable to fully charge fast enough to react.
He wrote the book, actually several books, on ESLs over the years.
Sure,.... using other people's work.
Sander's "original" amplifier design is shown here esl amp
Notice how Sanders claims HE chose the 8086 tube, and made modest design changes to Hermeyer's amp?
It's Dave's second amp design, published in a following issue - Dave gave him the schematic. (yes, I asked Dave - though I didn't need to, as it was obvious to me that Sanders couldn't design an amp if his life depended on it.)
Dave also advised Sanders on lowering the plate spacing to decrease the voltage requirements, advised him on plate material, diaphram material, coating material, panel size vs resonance, - Dave led him by the hand through his own project, with Sanders offering little more to the article than construction tips.
A real gentleman who knows ESL theory and practice inside out.
No offense, but looking at his current white papers - i.e. his "high current" amp - it's obvious to me that Sanders still has no more understanding of basic ESL theory than my dog,... he hasn't learned a thing.
Sorry if this sounds harsh, but I've watched folks heap praise on this guy for decades and enough is enough.
Keep in mind, Dave's final ESL system was published over thirty years ago, and yet it remains FAR superior in every respect to anything Sanders has ever, or will ever build.
Dave is the REAL gentleman here, and were he not, you wouldn't even know who Sanders is.
But back to the topic, direct drive HV amplifier technology has come a long way from the incredibly unreliable acoustat OTL tube amps, and being designed specifically to drive ESL panels, no other amplifier even compares.
This is an exceptional design from someone who actually does understand how ESL's work, and whilst it was admittedly a challenge to build, nothing I have ever heard in 30 years even comes close to the speed and detail.ESL amp
I've run these amps on Acoustat 2+2's, Hermeyers, and KHL 9's,.... absolutely astonishing.