Solid State Amps for Quad ESL 57?

Kalali         1/8/2017

+1

Nice thread !

 The loudspeaker/Amplifier partnership should be viewed as a matched pair.

When building a system one should first choose a loudspeaker, then find an amplifier (within budget) that is up the task. 

I made the mistake of purchasing a Quad 57, and was unable to find an amplifier that could do justice to it. I had to build a suitable amplifier. At that time ( A very long time ago ) the only serious amplifiers I was aware of were the Mark Levinson ML_2 and the Bedini. The ML_2 was the inspiration for my amp.

ML_2            Mono - Pair            25, 50,100 watts into 8, 4, and 2 ohms
My Amp        Mono - Pair           50,100, 200 watts in 8, 4, and 2 ohms
We never tested the amp at one ohm, but it was designed to be stable into one ohm. Eight 150 Watt Motorola bipolar output transistors per channel.

I bought a Bedini 25/25 in the 90’s, specifically for my Quads. Pretty good for ss, the poor mans ML 2! I still want to get a little Music Reference RM-10 for them, which is THE amp for the speaker. But I’m presently focused on my Tympani T-IV’s, which require very different amplification. I’ll be bi-amping them, with the wonderful RM-200 Mk.2 on the midrange/tweeter panels.

I wonder, just out of curiosity, what it would take to resuscitate a pair of those old Mark Levinson ML 2 amps. After all these years, they gotta have needs- are the parts unobtanium? I know Charlie King found a stash of some old ML parts at one point that he used to Frankenstein some tape preamps.
If I didn’t already have the Quad II amps, I’d probably be interested in exploring other options. I did get to meet Peter Walker back in the day--he was pleasant to talk to- I was pretty young, but he was polite and tolerated my questions.
In some ways, reviving this old gear is more interesting than buying current high end stuff off the shelf--I think my expectations are different, and there is something satisfying about getting a commanding musical performance out of an antique. I haven’t settled on a preamp yet for this "funk" system, but the McI MX 110z seems to ring a lot of bells- a bit of a sleeper since it isn’t a purist preamp only; has an FM tuner that could be a kick to use for a household system and looks like the build quality is stupendous. (Sympathetic restoration would be required as would a little tube rolling).
As to multiple systems being a cheap substitute for an uber system, I have yet to hear any system --at any price- that didn’t have some area where the illusion collapsed. Again, I think it goes back to expectations- you can get a hell of a lot of musical enjoyment out of older gear if you don’t expect it to do everything well. And, I might just be surprised- one pretty well known guru of old Quads told me I might find myself spending more time listening to this system than my "main" system--
I’m certainly open to that possibility. I’m a gear head for sure, but I’d really rather spend the money on records at this point in my life than constantly search for the latest and greatest. These last few years have been very gratifying for precisely that reason- my main system was pretty well dialed in, I knew what it could and couldn’t do, and focused on buying records. Now everything is packed and crated. The movers arrive in a few hours. Yay! :)

I am curious this morning and questioning this ML_2 that has been mentioned.

There are two outputs coming out of my preamp. One goes to the RM10 which is run full out to the Quads. The second preamp line out goes to the Subs which are set to cutoff at 60 hz.

I am trying to understand how the ML_2 mono pair, not having heard them, and just based on specs.....can get the job done. if I was using them I think I would need to use a higher cutoff on the subs?  

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From nyame’s post

ML_2 Mono - Pair 25, 50,100 watts into 8, 4, and 2 ohms

this implies to me and please tell me if I am wrong.

2..............4.............8............16..............32 OHMS

100..........50...........25..........12.5...........6.25 ML_2.....Output Watts.

***So only 6.25 watts available at 32 ohms***.

The Quad 57 use approx 32 ohms to make 100 hz. See the graph that was posted earlier and here it is again.

http://www.quadesl.com/graphics/quadGraphics/quad_impedance_graph.jpg

Somebody explain this one to me please.

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Whart - would have loved to have met Peter Walker in person. Also John Bowers.

Cheers Chris

ct0517                            1-09-2017

I am not sure that ohms law is the correct tool to unravel the mystery of the Quad 57 which present a capacitive load. My own experience is that very little power is required to reach acceptable music levels in a small/medium sized room. A friend of mine drove his quads with a 12 watt per channel solid state amp at bass levels which surprised me. 

Roger Modjeski  had the same experience: "The RM-10 came into being in early 1990, when I noticed I rarely played music above a few watts on my Vandersteen 2C speakers. Later, I acquired a pair of the old QUAD electrostatics and achieved the same listening levels at even lower power."