Solid State Amps for Quad ESL 57?

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Electrocompaniet 250R.

Rated output power

8 ohms 2 x 250 W
4 ohms 2 x 380 W
2 ohms 2 x 625 W
1 ohms 2 x 1100 W

Power consumption (no load or signal) 230 W

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in comparison
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Music Reference RM10

2 x 35 watts
Power consumption (no load or signal) 70 W

The real story - imo - is how much the wattage difference grows between two when actually listening to music.

And

For those that do not have a dedicated space and can’t position speakers for the best High Frequency dispersion; Roger provides the "Quad Mod" feature on the RM10.

This is a Switch which is designed to lift (boost the response) from 2khz - 20khz. It’s a 3 position switch ( +1, 0, +2 )

The +2 position adds a boost at 2khz of 2db - This, and I quote from the RM10 owners manual.

"Brings the speakers to the brightness level of modern speakers."

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So you see; you really can have your cake and eat it too. Especially if your wife will not allow you to place the speakers in the room as designed for the most detail. Gets the job done, but I have to admit....

Not as funky looking as some of those external tweeters I have seen hanging off the speakers. Hey......I used to hang the things off the speakers myself .....in the earlier days. My external tweeter versions had no dial or toggle switch, but used actual resistors that I could add and remove for the desired brightness.

One benefit of those resistors hanging there; it made the speaker look more dangerous, so the wife would steer clear. Now if I can just train my kitty to stay away from them :^(

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.