Solid State Amps for Quad ESL 57?

Clio09
In my setup I use a Luxman M-02 on the bottom and either the M-60s or RM-10 on the top. Instead of modding the Luxman to house the crossover I bought a used Beveridge RM-3 (designed by Roger) and made my own low pass and high pass cards (Roger still had some blank circuit boards for the RM-3 lying around).

Hi Clio09 - interesting as I also own a Beveridge RM3. I am not using it right now.
Would be interested to know what frequency you are crossing over at, and, if there is a difference in the Rm3's crossover box dial -  high pass "level" setting,  when used with the OTL M-60 versus the Push Pull RM-10. 
   
Cheers Chris 

One of the most memorable times I’ve heard a pair of single stack Quad 57’s, was with this little beauty from Nelson Pass, it gave them extension in the highs and a great taught extended bass with a midrange to die for.

It impressed me so much I built a massive 100watt class-a water cooled version of it to drive double stack 57’s Kelly Decca ribbon 12khz up, and 2 x 24" Hartley woofers for bass from 70hz down.

https://www.passdiy.com/project/amplifiers/the-pass-a-40-power-amplifier

Cheers George

George,

Interesting you should point out that Pass design. About 20 or so years ago N.E.W. loosely based their DCA-33 amp off the A-40. It was about 25 watts Class A and used a separate battery (lead acid) power supply. I owned this amp along with their P-3 preamp which was built for them by Cary and essentially an SLP-50. I still scour the ads for a DCA-33. Nice little amp.

Chris,

The crossover is 100 Hz. The ESL-57s have a 90 Hz bump so you want to crossover above that. The 8" woofers Roger selected can be built in a small sealed enclosure which allows them to have a resonance frequency above 100 Hz that compliments the crossover setting.

There is no significant difference in the RM-3 settings with either the amps. Sometimes I trim the high end a couple dB when running the RM-10 depending on the music. I run the M-60s with 4 tubes each channel so probably about 20 watts. I do use Speltz autoformers with them at 3x setting so that bumps up their power at some frequencies.

Hi Clio09 - the bass impedance hump at 100 hz can be managed by modified placement in the room, especially when it is a fairly large room. See pic 41 on my virtual system. It is roughly 20 x 24 with stairs going up at the back end.
I could never go back to running the speakers in stock mode on the 3 wooden legs. This setup with mid panel at approximately 44 inches, fills the room with sound. and also pretty much eliminates the head vice characteristic of the stock mode.
The preamp has two direct outputs. I am running the Quads full out on the RM10. 
My subs receive a separate direct signal from the preamp and are crossed over at 60 hz. The subs each have Class A/B amps with Linkwitz-Riley crossovers. So with the RM10, three amps are being used in the setup.

Chris,

Sounds like a nice set-up. What subs are you using? My room is 12' w x 18' d and there is a lot of stuff taking up space. So I am pretty limited in placement. I have them about 4' out from the front wall and they are on wood spider legs so they are lifted off the floor. This does make a difference versus the original feet in my opinion, although I'm sure Peter Walker had a good reason for having the speakers so close to the floor.