tube amps and electrostatics

Autoformers in finished boxes showed as costing over a grand. A barebones version would be less i suppose. Es speakers can be pricey, so its all relative i suppose.

Mapman, your original comment was

Autoformers cost more than many speakers themselves. That's a factor to consider in the equation that can't be ignored.

If you're talking about some of the smallest hybrid ESLs on the market, especially purchased used, you may have a point, but that is not 'many' compared to prices of ESLs currently manufactured and certainly not the majority no matter how you slice it.

Thanks Al.... Headphones is where my wife wants me to go. When my wife begs me to lower the gain, and then violates the serene sanctity of my blessed man-cave when she does so, I promise to turn the rig down, but turn it back up even higher when she leaves. LOL :)

Clearly Al, you are much more the gentleman than me because you switch over to headphones so as not to "conflict with [your] wife's activities." AL, ... I'm 19-year old child trapped in a 60-year old body -- just like a rat trapped in a steel cage.

I get the idea that negative phase angles coupled with low impedance attributes in a speaker's bass frequencies makes for a difficult to drive load. But good ole' George dropped a new term on us tech newbies, "EPDR (equivalent peak dissipation resistance)." Que'est ce se mon amies??? [What does it mean my friends?]

All the best guys. And ok, I'll put ESLs back on the speaker possibility list.

Regards,

Bruce

"EPDR (equivalent peak dissipation resistance)." Que'est ce se mon amies??? [What does it mean my friends?]"

It is used by technical measurers like Keith Howard of HiFi news & Record Review, and John Atkinson of Stereophile when they review and then measure speakers. Because just a low impedance measurement does not reveal all that the amplifiers is seeing as a load.

The lowest EPDR (combind resistance and phase angle) of say the Wilson Alexia when measured by Keith Howard of HiFi News was a low impedance of 1.8ohms at 65hz and a lowest phase dip of negative -40degrees also at 65hz. These two measurements combined gave the Alexia a load to the amplifier of .9 of an ohm at 65hz. Big difference to just 1.8ohm resistive load.
You can read all about it here.

http://www.absolutesounds.com/pdf/main/press/WA%20Alexia%20HFN%200313-4web.pdf

Cheers George

"increased emphasis of the upper treble"

Not right, "emphasis" is the wrong word it will give a flat response through the audible frequency range and cannot boost at these frequencies thus will not be effected.
And yes it will have more presence than an amp that is curtailed in these harder to drive areas because they cannot deliver the constant voltage because of limited current.

Just read and try to understand Roger Sanders WHITE PAPER on the subject.
http://sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors

Cheers George

Thanks George, I read the article that uses the term EPDR. It appears to be a numerical factor that in some way combines and restates a speaker's impedance and phase angle attributes at a specific frequency as some sort of "impedance prime" equivalent.

Is there a formula that would enable one to make an EPDR calculation? What about cases involving inductive phase angles? How is EPDR computed in such cases? Are they hard on amps (tube or SS) like capacitive phase angles? Lastly, how significant is a low EPDR at a particular frequency when the frequency range where the EPDR is low may only be 10 or 20 Hz wide??