Solid State Amps for Quad ESL 57?

Chris (ct0517), I believe the RM-9 is no longer available, even as a special order. I could be mistaken however. Roger has relocated to the Bay Area, and appears to be more involved in his Audio Engineering school than in running Music Reference. He has a right-hand man still operating out of his old Santa Barbara location.

Sorry I am late to this thread and for the long post. I don’t hang out much here anymore, but I’d like to point out a few experiences of my own as a Quad ESL-57 user. First though I’d like to address the quote above. Music Reference is alive and well and in the Bay Area, the right hand man in Santa Barbara is no more and I have been helping Roger for the last year and a half. We also have a couple more folks working with us now.

While the RM-9 is no more, we have a few RM-9SE’s left. Otherwise we are still producing RM-10 and RM-200 amps, and Roger has some new designs he is tinkering with. We also just introduced a prototype for an ESL Headphone Amp (that also plays dynamic and planar headphones and doubles as a preamp) and it was received really well. It will be in production shortly.

Now to the ESL-57. When I purchased my set it was more out of curiosity, but once I heard them with my Atma-Sphere M-60 amps I was hooked. I also own an RM-10 and this little amp as previously mentioned is a great match for the speakers. I ran the ESL-57’s this way for about a year. Then Roger Modjeski introduced me to something new.

Roger, while owning ESL-57’s, also built his own ESL speakers which we exhibited at THE Show Newport 2016. In this biamped configuration Roger uses what he calls the AirSpring Woofer system. It’s a woofer array of 2 or more woofers operating below 100 Hz. The low pass is a 4th order L/W crossover specially tweaked with a passive EQ circuit taking the panels down to 32 Hz (can go lower with the change of a resistor). A modified Class AB solid state amp with the crossover circuit built into it handles the woofers. The high pass is also L/W Riley and covers 100 Hz and above. We used an RM-200 and RM-10 on the top.

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). I use 4 woofers spread asymmetrically around the room (similar in theory to Duke LeJeurne’s Swarm concept) to eliminate bass nodes tune the set up. The RM-3 has bass and treble trim controls so those come in handy as well.

Overall I can say this is very pleasing set up. I occasionally still use the ESL-57s stand alone to much enjoyment as well. An amazing speaker to say the least

Disclaimer: Atma-Sphere dealer and I work with Music Reference RAM Tubes.

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.