What amp should I buy to power Martin Logan Esl's?

Bombaywalla, how do tube amps mate with ESL/capacitive loads? I kinda' recall that tube amps "generally" like resistive loads with positive/inductive phase angles. Come to think about it, I'm not so sure that SS amps particularly like super-low impedance loads with large negative phase angles.

Thanks Bombaywala -- very good explanation. After breaking big rocks with a sledge hammer, courtesy of Ralph and Al, I'm starting to better understand speaker/amp electrical matching. Of course, I've also come to better understand that speaker and amp designs are often the result of engineering/technical compromises. I believe Al and others made that point as well many times.

One such compromise that comes to mind is the benefit and cost associated with using negative feedback. Ralph and Al have spoken about many of the costs, such as TIM distortion and odd ordered harmonic distortion. They have also mentioned some important benefits, such as lower overall distortion, increased bandwidth and lower output impedance.

Case in point: I believe that ARC uses NF in most (if not all) of its tube amps. For example, the somewhat new ARC Ref 150 tube amp uses 14 db of NF and has approximately 1.1 ohm output impedance off the 8 ohm tap and about 60% of that value off the 4 ohm tap. See Stereophile/John Atkinson Ref 150 bench test last year.

Not sure if that turns a low impedance/high capacitance ESL speaker into vanilla ice cream for the Ref 150. Not even sure if the Ref 150 likes ice cream. But I wonder how well tube amps that use NF fare with ESL loads.

Bombaywalla, not sure what constitutes "large amounts of NF," but the ARC Ref 150 uses 14 db of it. Perhaps somewhat responsive to the issue of tubes and ESLs, ARC reports (and Atkinson confirms) that output regulation is approximately +/- .5 db off the 4 ohm tap. So ... maybe the amp may add a touch of "flavor" to the acoustic presentation, but who said life is perfect.

Can't say that I recall reading comments that the Ref 150 doesn't sing to the music, but I'm tone deaf. What do I know??

I suppose we still don't know for sure what all the techno-babble means in real life. So I echo Bombaywalla's request that folks who have matched tubes and ESLs report their real-life experiences. Kinda' an interesting topic.

Bombaywalla -- you're right ... the Ref 150 is of personal interest to me. But not because I own it, but rather because I want to own it. ;>')

Having said that, if there is any validity to my thesis that tube amps using NF may (??) perform SS-like, and therefore may (??) be able to drive ESLs, does go to the OP's thread about ESL-amp matching.

In short -- I don't know the tech answer to whether a particular tube amp will match well a particular ESL. Perhaps the best way to answer the Q is to ask the manufacturer. Of course, a live audition, if possible, would be great.