Electrostatics and tubes

To add to Ralph’s (atmasphere) expert commentary, probably the most transparent music reproduction I have ever heard was a pair of QUAD ESL’s driven by a pair of his M-60 OTL amps.

Roger Modjeski was also a huge fan of the QUADs, and used that loudspeaker as one of the loads in the development of his Music Reference RM-10 power amp. Roger then took the ESL/tube pairing to it’s ultimate realization: he developed an amplifier in which the tubes directly drive the ESL stators, bypassing the input transformers of the QUAD. He made only a very few pairs of that amp before Cancer ended his life in 2019. I can only imagine how transparent that Music Reference/Direct-Drive ESL pairing must sound.

Let's clear up something here. Roger's direct drive amplifiers were made for either the Acoustat ESLs (non-hybrids) or his own ESLs. None were made for the Quad ESLs (the voltage was too high). The RM-10 was manufactured during the time Roger owned Vandersteen and Quad ESL speakers so those are the speakers he tested the amp on. By his own account he was surprised how well the RM-10 behaved on the Quad ESL. The key was that the output of the RM-10 was 35V which was the maximum tolerated output of the Quad ESLs so the amp wouldn't overdrive the bass panels. By his own admission Roger acknowledged in my presence while listening to the RM-10 on my Quad ESLs that while it was a nice amp for the speaker, and pretty flat, the bass was a bit lean.

Thanks for the clarification @clio09. I believe you have corrected me on that matter before .

I attended the talk Roger gave at Brooks Berdan Ltd., in which he introduced the RM-10. At that time I had a two pair of QUADS, mounted in a frame of my own design. At that talk I asked Roger if he recommended a single RM-9 or a pair of RM-10’s (one on each speaker pair) to drive the four ESL’s, and he told me a single RM-9. He said he did so because of the RM-9’s greater headroom capabilities.

At his next visit to Brooks’ shop, he came over to me and said he had been thinking about my question, and had changed his mind: he now recommended one RM-10 for each ESL pair. By that time I had returned to a single pair of QUADS, so the matter was moot.

I also owned a pair of the QUAD II tube amps made for the ESL’s, and it was easily outclassed by the RM-10. Bill (@whart), you really should get yourself a Music Reference RM-10 Mk.2 for your QUADs!

 The Link shows a variety of info relevant to the Quad ESL Development.

At the end in the Red Highlight, there is a reference to EAR having a Amp Design to be coupled as a Direct Drive. I have heard the Public Demo' of these in the 90's and from that day on, ended a search for a Speaker. The experience is one of the most indelible for being extremely impressive, I have had during my long term interest in using Audio Equipment 

I am a original 57 user and this evolved into using a Stacked Pair of rebuilt 57 models using One Thing Audio replacement Treble Panels.

I also as a result of the impression made by EAR, had Monoblocks Power Amps, Designed / Commission Built using 845 Tubes and Hand Wound Transformers to drive the 57's. 

I am also very Familiar with Quad ESL's owned by other, being 57's and stacked 57's,  the 63 model from different era periods of production, through to the 2912.

The 57's in a Good Condition !!, hold their own in all Quad ESL Company.

Early production 63, built as the first 200 Models has been used in demo's against 57's ,a later model  63 and 2912's, where the early production 63, has stood out as attractive in use as the 57 and 2912, this is a very difficult find, leaving the early and later Quad Models as the easier options to acquire.

Later model 63's in my experience of the ones demo'd, are enjoyable when encountered in use, but when used as part of a demo' comparison to earlier / later Quad ESL Models, the later model 63's I am familiar with are shown to be wanting more of an improved end sound to compete.

The 57's and 2912's are used in different systems regularly listened to. As systems, these have also been used to add other types of audio devices to for demo' purposes.

Whether the 57's and 2912's are being used with a different Source, Analogue Digital, Pre Amp Design as SS or Valve, Power Amp's as a SS or Valve. The 57's 2912's are always able to offer an impressive end sound, as well as easily be able to produce a sonic difference to help evaluate a change being made with a Systems devices.

https://www.quad-hifi.info/public/esl57%5B3015%5D.pdf

I have owned Quad ESL-63s electrostatic speakers since I imported them from England in March of 1985.  I imported Quad amp and preamp at the same time but eventually replaced the electronics with a tube amplifier, an Audiomat Arpege integrated amplifier from a French company that is 30 wpc.

I should mention the reason I went to Quads in the first place was due to a chance reading of an article in Opera News that Quad Electrostatic speakers were the ideal speakers for opera lovers.  I love opera music and I love classical music and my experience suggests that the author of that article was absolutely right.  Quads are ideal for listeners who especially love the mid-range.  Voices, violins, piano, cello, guitar, etc etc sound so utterly natural and beautiful as though live in the room with you.   I eventually upgraded to an Audiomat Prelude Reference  MKII, another 30 wpc tube integrated amp that was an Arpege improved.  Just a wonderful integrated tube amplifier.  I also played with putting my stored in a closet Pioneer SX-1050 with 120 wpc to my Quads before I decided to buy the Prelude and it sounded great but I was worried about putting too much power to my beloved Quads, so I decided to go with the Prelude.  Besides, the Quads seem to be made for tubes.  That is their natural partner.

In 2017 I had my Quads completely refurbished.  What a treat to listen to them!

Many wonderful years later, I happened to audition a Luxman Tube amp and preamp that sounded beyond wonderful with my Quads.  Well over my price range of course, but I decided to buy them anyway.  

Then along came an opportunity to buy the US Monitor version of the Quad ESL-63s.  This from a friend who was downsizing.  He had just bought them from a refurbisher of Quads, so they were almost liked brand new!  
 

I have been invited to listen to the systems of fellow audiophiles and so far my system sounds better than some costing thousands more.  I attribute this to my Quads and their ideal pairing to high quality tube amplification.

The only way to criticize them is to knock their base. they don’t have a great bass but, honestly, I’ve never minded. I could add a sub, but I haven’t found it necessary.  I’m now 85 and I like to joke that I want my Quads buried with me.