tube amps and electrostatics

"12-09-13: Bifwynne
George, I did a web search for an article that explains EPDR."

Good to see someone is starting to grasp it, I posted (link) 2 graphs of the B&W802D one that shows the impedance and phase angle as separate measurement lines, and the other graph in red that shows them combined to give the actual EPDR load the amp is seeing.
Note the big difference at 60hz and at 700-800hz where the load the amp sees, drops to almost 1 ohm (EPDR) from 3ohms (non EPDR)
http://www.stereo.net.au/forums/index.php?/topic/59228-class-d-amplification-explanation/#entry1010538
And look at the Wilson Alexia comment as well.

Cheers George

These links will get you there better

B&W802D EPDR load
http://www.stereo.net.au/forums/uploads/monthly_12_2013/post-106386-0-82896500-1386705003.jpg

B&W802D non EPDR load
http://www.stereo.net.au/forums/uploads/monthly_12_2013/post-106386-0-58273700-1386705013.jpg

Cheers George

The B&W 802D is, FWIW, an excellent example of Voltage Paradigm technology.

The woofers are each 8 ohms, but also 3db less efficient than the 8 ohm mid range and tweeter. They are in parallel, which requires the amplifier to double its power into the woofer load. This brings their output up by 3db, causing them to match with the rest of the speaker.

Yet the spec on the speaker says they are 'nominally 8 ohms'!

The requirement of the speaker is such that almost any amplifier driving it will have to have a fair amount of feedback to do so. This will cause the amp to be un-naturally bright. IMO this makes the speaker a poor choice as you will not be able to find an amplifier that will actually cause the combination to sound like real music.

This is not true of ESLs.

"The requirement of the speaker is such that almost any amplifier driving it will have to have a fair amount of feedback to do so. This will cause the amp to be un-naturally bright. IMO this makes the speaker a poor choice as you will not be able to find an amplifier that will actually cause the combination to sound like real music."

B&Ws like those often tend to sound bright to me as well, but not always.

I'd compare those to my OHM Walsh speakers, which has impedance drop just below 3 ohm in teh mid bass region based on measures I have seen, but seldom ever sound naturally bright. There a single Walsh style driver does most of teh work up to 7khz or so. There is no driver efficiency mismatch issues to deal with in teh case of the OHM CLS driver. I suspect that might be part of the reason.

MY Bel Canto Class D amps use feedback as well. Brightness and/or fatigue is a non -issue.

I auditioned modern Quad ESLs prior to trying the OHMs. They were a reference standard for me as I heard them in every area except microdynamics. The OHM sound resembles that ES sound with the right amp + the macrodynamics one associated with a traditional dynamic driver.

"They were a reference standard for me as I heard them in every area except microdynamics. "

Whoops, mean't to say macrodynamics there actually. Sorry. ES speakers I have heard tend to have microdynamics in spades.