Electrostatics and tubes

I found that the newer ML ESL are very efficient. I had no trouble running my EM ESLs with a 25 or 45 watt tube amp. On the other hand Magneplaners need real power. I ran those with a Parasound A21 after trying a couple of tube amps. Magnepan doesn't demonstrate with tubes amps for good reason.

Mags aren't stats.  They sound different.

@russ69 

Well that is part of why I stated I would be using M-125's, I decided to go with the 125 watt mono blocks. not because of wanting ear splitting loud but to just have the power if needed,  I've always felt that it's better to have and not need over need the power and not have it.  Obviously a 125w tube amp is no match to the power that Parasound puts out. 

I remember some discussions I was having with someone on another forum (he was helping me troubleshoot a tube amp) and he told me that he has electrostatic speakers (I seem to remember he said that they were "true electrostatic speakers" and that they each had to be plugged into an outlet, I think maybe he said that they were "Quads"?), anyway, he was using an ARC (tubed) 70 wpc stereo amp to drive them with and he was quite pleased with the system.  He referred to it as "holographic."

If you are considering Martin Logans, the place to check is:

https://www.martinloganowners.com/

Lots of in detail discussions on what types of amps to use.

I run a vintage system downstairs (separate from the main system shown in my profile here) that consists of a pair of Quads I bought in 1974. They were restored by Kent McCollum at Electrostatic Solutions in 2017. I had put them away back in 1990 in favor of a pair of Crosby modified Quad 63s. In both cases, I originally drove them with a succession of ARC tube amps in the 60-70 watt/channel range. They were both revealing speakers, though I preferred the original Quad to the 63.

When I had the old Quads restored, I also had Bill Thalmann restore a pair of old Quad II amps which make about 15 watts each. I have extremely good glass in these- real GEC KT 66s that I found some years ago, NIB, along with the proper Mullard rectifier tube and opted for a GEC driver tubes that were meant to be hard wired but were converted to conventional tube pins by Tubemonger. Those amps with that speaker are magic. But, they have significant limitations. Back in the day I augmented them with Decca (later Sequerra) ribbons and a few odd subwoofers. A single pair of Quads doesn’t quite cohere doing this but a double pair ought to. That was a "thing" back in the day.

I still enjoy the old Quad system for what it is and on certain music, they are incredibly "transparent" sounding but at the same time, almost act like a noise filter, eliminating some of the gremlins you might hear on a more revealing system. They also have a wicked impedance curve which makes certain amps unsuitable to drive them, and a tendency to "arc" if overdriven. (McCollum installed a protection device to prevent this).

I recommend that people get to hear a pair at some point in their lives because they are part of audio history. I think it takes a special kind of listener to appreciate them long term, though. For me, it is easy enough to go to the big system if I want to recreate a large presentation in more realistic scale, but for small scale works, they remain a marvel. The audio fora are rife with stories of people who owned, sold and then bought the old Quad again.

I get great satisfaction from this system, which in good part, I’ve owned for 50 years, even if it isn’t a complete "all-arounder" as systems go.

I drove Martin Logan Montis with Rogue ST100 tube amp without any issues whatsoever. Keep in mind the MLs have powered woofers so the only load is the panel.

"Obviously a 125w tube amp is no match to the power that Parasound puts out."

Not sure you are hearing me. Those will with work with newer Martin Logans. The 250 WPC Parasound was in a small room. Magnepan was using 1000 WPC mono blocks. Not sure how loud you play but Maggies NEED real power. My brother smoked his JC1s running a 3.6 Maggie. That’s 450 watts per.

@russ69 

No I get what you're saying,    and you basically answered my question earlier about the Maggie's, I've heard they are power hogs before.  And I was worried about under powering them and overheating the M-125's  I do know ML ESL11's have a sub amp built in, but the ESL 9's do not, so stick with the 11's.   But regardless I was thinking about possibly using a separate sub so that wouldn't matter.  Overall it seems most everyone that has answered so far believes a 125 watt would be good on a ML but not so much on a Maggie. Unless anyone has other suggestions on speakers under 5K. 🤔

@hotrod6871 

I have some Accoustat Model X electrostatic speakers.  They are attached to some 40 watt tube mono blocks and they play louder than I can listen to. When I added a crossover and a subwoofer or two, they easily filled a 22’x20’ room and the volume control never passed 50%.

All the best.

I've been a stat fan for nearly 40 years.   I find the pairing of electrostats and tubes to be magic.   Electrostats are typically 91-92dB efficient, so you don't need a ton of power.   You should have plenty and those VTAs are sweet.

I'm not a fan of the ML ESL9, but the 13a and 15a, I like a lot.   Mating your excellent amps with the ESL9 is like putting a Ferrari engine in a Chevy Malibu.

Good luck.

Electrostats are typically 91-92dB efficient, so you don’t need a ton of power.

’Typically’ is not a term that should be used for electrostats. They’re all different.

The important specification to look for is the impedance curve - not the db sensitivity. Is the curve relatively flat - or is it jagged? Some stats go down to 2 ohms or less - which very few amps can drive - either tube or solid state. Many variables to consider - including room placement, to account for the backwave.

OP: Be sure to do some research first. Many stats have a very narrow sweet spot. When leaving the listening chair, the presentation falls apart if you’re somewhere else in the room. After owning a pair for 5 years - with 2 subwoofers, I was happy to move on.

Have you seen the new FINAL brand ESLS.

https://www.audiogon.com/listings/lisb90bc-final-electrostatic-esl-hybrids-m3-m5-m7-innovative-design-exquisite-high-resolution-planars

@russ69 from what I'm reading their speakers aren't really reliable and customer service with this company is severely lacking.

@willywonka Where are you reading that the Final speakrs aren't reliable?  I believe the new M35 comes with a 5 year warranty.  Distribution in the US just started so nobody really has experience with them here.

@hotrod6871: The first thing to do is understand that---as @fuzztone told you---Maggies are not electrostatic speakers (and visa versa of course), and the two differ in important ways. What they both are, however, is dipole planar speakers. Dipole as in sound emanating from both the front and rear of the panels, planar as in sound being produced by not dynamic/cone or horn drivers, but by large (with the exception of ESL tweeters like the 3" x 5" ones made by RTR), thin, flat sheets of Mylar. The difference between Maggies (and other planar-magnetic loudspeakers. Magnepan is not alone in making them. See below) and ESL’s is in how the Mylar is set in motion. A google search will explain it all.

If it is Maggies you are considering, you should know that they present a 3-4 ohm load to the power amp, and are very insensitive: 83dB or thereabouts. The load is almost purely resistive, unlike ESL’s, which are in some cases very reactive. The original QUAD ESL is one such case; it presents as low as about 2 ohms up to 50 ohms to the amp, so is highly-amplifier sensitive. The QUAD is not for those new to dipoles, one reason being they are very limited in maximum SPL capability. The speaker is really, really great for "small" music.

But to answer your question, yes, the power needs of Maggies is emormous (I’ve owned three pair in my life, one currently). Depending on the size and sound characteristics of your listening room, and your SPL listening preferences, 125 watts may be marginal (though there are many happy owners of the Maggie/ARC amp combo). Relieving the panels of reproducing low frequencies by adding a sub or two, along with a x/o filter to split the signal at somewhere between 50Hz-100Hz, will greatly reduce the power requirements of the panels.

It might be a wise idea to give a modestly-priced planar-magnetic speaker a try first. Magnepan designed and offers the LRS for exactly that purpose. Spending $6000 on a pair of MG2.7i is to gamble a fair chunk-o-change on liking them enough to keep them. Have you heard any Maggies? How about ESL’s? I would characterize ESL’s as being a little more transparent than Maggies, though the Magnepan ribbon tweeter used in the MG2.7i narrows the gap. A major complain about Maggies is their slight lack of dynamic expression. They also become somewhat opaque at low listening levels.

If you care to consider another planar-magnetic that isn’t as power hungry as Maggies, there is the Eminent Technology LFT-8b, priced at $3200 (including shipping). The LFT-8 has dual binding posts, one for the panels (180Hz up), the other for the 8" dynamic woofer (180Hz down). That makes bi-amping easy: a solid state amp for the woofers, your M-125’s for the panels. The LFT-8 is rated as an 8 ohm load (with about the same sensitivity as Maggies), but the panel itself is an 11 ohm load, which your amps will love.

Here’s a fairly recent review of the ET LFT-8b by Steve Guttenberg:

https://youtu.be/Uc5O5T1UHkE?si=frZqh9SRwmwjJ0MM

I tested my ML CLS, a very hard speaker to drive, when I had a Decware ZMA (pp, 24 wpc) and it did well in the midrange and highs, where that speaker thrives.  with a subwoofer, it sounded great.  

As others have said, the ESL series should work fine with a moderate power push pull amp.

Jerry

@bdp24 Nice summary. I've owned planars since 1973 (Magnplanar Tympani 1a's). I've also owned SMG's, MGII, and MGIII. Also Martin Logan Prodigies, Quad ESL57, Quad 2805 and 2905. Current system is Quad 2805, 2905, Magneplanar DWM (x2), and DIY sub.

I currently drive everything with solid state, Quads with DIY pure Class A, DWM with Bryston. One thing that hasn't been mentioned yet is hot-rodding. Magnepan speakers can be immensely improved with better capacitors (film and foil) and with bracing (Mye stands or equivalent). Quads can be significantly improved with better power supplies (Electro-Static Solutions) and better step-up transformers (Plitron). Don't know about Eminent Tech - I would ask them - but remember that all hybrid systems have an integration issue, that is, integrating a cone with a panel. Some are more successful than others.

Good luck - it's a great journey!

Electrastic like Martin Logan’s with the right power tube it will work. Many years ago I heard Martin Logan statement hook with VTL wotan monos. The sound is amazing.

In the end of the day you can always add an outboard transformer (Autoformer) to help with impedance matching issues when using either of these. This can help with the really low impedance of Magi's and some ESL's. This should be fine with your amps especially if you have sub('s). maybe something to consider if you want to try without upgrading amps power etc. 

Speaking as a past Magnepan owner, what I'm hearing is that you own a Ferrari and you want to put a diesel engine in it, or is it vice versa?  Had the 3.5r's that were some of the most exact sounding speakers I have ever had.  I played with a ATI 1002 and a Audio Research VS55 and they didn't want to sing at all.  With a McIntosh MC-7270 or a Rotel 2-channel biggest they ever made (don't remember the model number), they were beautiful.  Maggies are slightly more efficient than a slab of marble. 

We have owned the same pair Quad ESL-57s, bought new in 1979. Before that, another set that we sold because they were copper, we wanted black. If you really want some fun, ask if the copper or the black Quads sound better. We have run them successfully with a Quad 405 current-dumping solid-state (100W x 2), and now with an Audio Note Cobra tube integrated (28W x 2). The Quads sound much better with the tube amp and there is plenty of power. We recently replaced the Jolida JD100 tube output CD player with the tube output Audio Note CD 3.1x/II player. Again, a remarkable improvement. I think electrostats, at least ours, are MUCH happier with tube power. You can purchase used and refurbished Quads from reliable people. The sound is something to experience - so transparent, it is spooky.

@terry9 and @sierratrails: I’m amongst friends!

In the spring of 1973 I paid my first visit to one of the new high end shops that were popping up around the U.S.A. in the wake of The Absolute Sound joining J. Gordon Holt’s Stereophile (Gordon was the mag’s founder and chief---often sole---reviewer) to serve the hi-fi appetites of we boomer generation new audiophiles. The shop (named Audio Arts) was located in Livermore, CA---about halfway between my town of San Jose and the state’s capital, Sacramento (where my mom was born and raised), and was owned and operated by a fantastic guy named Walter Davies, later known for his Last Factory record and tape care products..

Also paying his first visit to the shop that day was Bill Johnson of Audio Research. Talk about good luck! Bill was a pilot with his own little plane, and he flew himself and a complete ARC/Magneplanar system from Minnesota to Livermore, to install in the shop’s excellent listening room (one of the best I’ve ever been in). Back in 1971 I had seen an ARC Dual 50 in San Jose’s best hi-fi shop, but at that time the name meant nothing to me.

The Dual 50 was driving a pair of ESS Transtatic I loudspeakers, for which I was lusting (they unfortunately cost $1200/pr, which at that time this starving musician couldn’t sell enough blood to buy ). The Transtatics featured three RTR ESL tweeters, the first ESL’s I had heard. They reproduced the sound of cymbals as I had never before heard. I now own a pair of them, bought used in 1982 for $400.

Anyway, I spend a few hours listening to Walter and Bill talking all things hi-fi as Bill installed the system, getting myself a nice education. The system was a pair of Magneplanar Tympani T-I loudspeakers bi-amped with D51 and D75 amplifiers, an ARC SP-3 pre-amp, and a Thorens TD-125 Mk.2 with a Decca Blue pickup mounted on a prototype ARC tone arm not yet in production. That was the most consequential day of my hi-fi life! Having heard that system, I just HAD to get it for myself.

Later that year Walter installed the exact same system in my listening room, minus the ARC arm. I paid for the arm upfront, but used a Decca International Arm (on loan from Walter) as work on the ARC prototype proceeded. When the arm was cancelled (it never went into production), I got myself an SME 3009 Mk.2 improved. In using the Decca arm I learned that I don’t care for unipivots.

I was happy with the system for about a year, but when I heard the new Fulton Industries Model J loudspeaker---which used the same RTR ESL tweeters as the ESS Transtatic (as did the original Wilson WAMM, along with a pair of KEF B139 woofers, also the woofer in the Transtatic), though six of them, and a dynamic woofer in a transmissionline enclosure---well, the failings of the Tympani’s became glaringly obvious. Out came the Tympani’s, in went the Model J’s (the sale of the T-I’s and D51 paid for them).

But the honeymoon was short lived; I quickly learned that while the J’s were indeed more transparent than the Tympani’s, and had greater low end weight and extension, the vocals and instruments sounded like they were being squeezed out of three boxes (look up a pic of the Fulton’s to get the picture). Images produced by the Maggies were spread out before me, floating in space, free of the Mylar diaphragms producing them. With the Fultons, those same images were coming through little holes in the wall at the location of the speakers. I learned I was a planar man.

I now own the Transtatics, a pair of Old Quads, a pair of Tympani T-IVa (bought from Kent of Electrostatic Solutions), and two pair of Eminent Technology’s: both the LFT-4 and LFT-8b. Plus Rythmik Audio and GR Research subs. What I need now is a room big enough for them all .

For those who don’t care for this long-winded tale, my apologies. My last of them, I promise (and this time I mean it).

Just to pile on a bit, I have the Magneplan 3.6r with dual self-powered subwoofers driven by an NAD M33 which is rated at roughly 380wpc at 4 ohms, and I would consider that the minimum.   I'm considering trying a Bi-Amp setup using the companion M23 amp one of these days; I just don't get enough chance to enjoy them since work tends to keep me busy.

Try to audition a pair of Martin Logan's with the powered bass cabinets (Ethos, Montis, etc) ....takes the "weight" off of the tube amps for powering the lower frequencies.

Seems like there is a lot of dialog with watts and playing loud. I own Electrostats and Maggie's.  All of my amps are Monoblocks pushing out over 700 watts per block. Sometimes I play them loud,  but most of that power is for the dynamics, power in reserve for the speed, control and peaks that will make those panels sing. You can play loud with any amp, if you like distortion. The high wattage,  high amperage power amps are what's needed to get the most out of your panels at any listening level.

Amplifiers: Voltage vs Current

Speakers: Voltage vs Current

@whart

Your message made my heart beat faster. I also restored a pair of ESLs and Quad IIs during the 70s and still groan at having been forced to sell them at liquidation prices when I was forced to downsize in retirement.

FWIW, after spending years pairing the speakers with numerous power amps, I could not find a better match than Quad's own 1950s-vintage Class A Quad II monoblocks.  Today, I listen to gear that is an order of magnitude pricier than my old ESL/II combo, but in many ways, the Quads still remain unmatched.  Que lastima.

Boy, you would have loved the Quad IIs when they returned, all shiny and refurbed, from Quad’s UK factory!

Here are the only photos I could find, shot at different times during the restoration process. You can see my 220V Quad IIs to the right of one of my Dynaco projects-in-progress, as I originally purchased them, including NOS Quad-branded tubes.

I ran MartinLogan THEOS and my current Magnepan 1.7i's with my Primaluna Dialogue Premium HP Integrated amp with absolutely no issues. Both sets of speakers sounded stellar. 

A good set of tube amps will be magic with M-Ls. I have an older pair of Sequel II's which do have lower impedance than the more current versions of their ES Hybrids. These speakers and some ReQuests I heard (back in the day that the ReQuests were being sold new) driven by ARC tubes was the best sounding  system I had ever heard, for under $20K, save for my friend's $15K Sound Lab A1's driven by Jeff Rowland amps. He and I went to a demo of Boulder amps with a total system cost of well over $100K and it's couldn't touch the quality of full range sound of the electrostatics.

@hotrod6871 If all I ever drive is a Honda Accord, it would be fine to get me from place A to B.

I would never know the excitement of stepping on that pedal, hearing the engine rev and deep sound of the exhaust note coming from the rear. I would never know that feeling of coming up on a curve in the road, stepping on the excelerator as I reach the apex. If I drove a Corvette or Farrari,  I would know all those feelings.  A low watt tube amp will give you all the excitement of the Honda.  You will hear sound from your Maggie's or Electrostatic speakers,  but you won't feel the music. Most of the tube people will say, they play just fine, they would on a highly efficient speaker. And since they are driving the Honda, they don't know the difference. I would say, buy a used Classe Amp, one with 200 watts and over. You'll be able to find one on this site for around $2000. Test it against the tube amp you want to get. Those older amps hold their value and if it doesn't work out, you can sell it for what you paid.

I am not downing tubes, my front end on my Maggie system is a Bottlehead Foreplay,  backed by Classe CAM350 Monoblocks. My Acoustat Spectra 33's are backed by Acoustat TNT200's Monoblocks by Roy Esposito. All this to say, I've been around the block with panel speakers and I know what drives them best.

Enjoy the Music

@cundare2 - I'm glad you got the old Quad gear restored, though you had to sell it. No images appear- as far as I know, you have to host them through a third party source, and then use the image function in the tool bar above to paste in the url where the images are hosted. 

I did write A Tribute to Quad a few years ago which is online and may have mentioned that I did get to meet Peter Walker at the 1976 CES in Chicago. He was "showing" in a humble little booth at the same time the big electronics firms had revolving displays with attractive female models in bathing suits. Kind of brought home the contrast in approach. These days, I still enjoy the Quad system, though I long recognized their shortcomings. And yes, those modest Quad II amps do sound better (based on sonic memory) with the original Loudspeaker than the more powerful ARC tube stuff I used for a few decades. I found the 63 to be a better all around speaker, but even with the Crosby mods, it did not have that eerie see-through quality of the original. My punchline was that listening to this antiquarian system showed how far we have not come, despite all the technological advances since the '50s.

Best, 

With my ML ESL 11a speakers, I use an audionet V2 amp 250 amps into 8ohm 450 into 2ohms. Works well for me. Tried a premluna tube power amp, preferred the solid state. I think you need to try a few differnt amps to find the sound you enjoy.

I’ve owned 10 different types of Martin Logan’s for 32 years. From 3 different sets of CLSiiz’s to Summitt X’s. The story of current ML’s being inefficient is tied to the fact they were 20 years ago. Not anymore. So buy your 9’s and simply enjoy them. Cased closed. 

MartinLogan ESL speakers highest current draw is in the highest frequencies where there is usually minimal recorded sound which make them easier to drive than expected. Currently driving my ML-11a's with a Mcintosh ma352 with no issues.

Steve Guttenberg followed up his review of the Eminent Technology LFT-8b with a review of the new LFT-8c. In the review he gives his opinion that the 8c is a significant upgrade from the 8b, and that he considers it superior to all Magnepan models, and all ESL's (of which he is not a fan). Here it is:

https://youtu.be/R4vC3V00-3Y?si=stiLs8kZ25TJhRsd

Nice!

@bdp24  Steve also has a review stating how he doesn't like Electrostats..

Right you are @gumbedamit. He says the same in his reviews of both the LFT-8b and 8c. It can be argued that the opinion of ESL’s by one who doesn’t like ESL’s is of no value. Just as an opinion about a, say, horn loudspeaker by one who doesn’t like horns (I admit to being one such person) is meaningless.

Still, I find it of interest that Guttenberg characterizes the sound of the ET LFT-8 (both b and c iterations) to have the best traits of both ESL’s (transparency) and planar-magnetics (very well known in the Magnepan designs), with less of their faults.

I understand Guttenberg’s reservations about the ESL sound, though I don’t agree with his dismissal of the design. All speakers are a combination of strengths and weakness, and every listener must decide what his or her priorities are, and look for a speaker that provides he or she with the most of what they are looking for at a given price. I find the ET LFT-8 to offer a nice balance of attributes at a very modest price, and remain mystified that the speaker is not more well known and owned.

It took Guttenberg 30 years to get around to reviewing the LFT8! Robert E. Greene also reviewed the LFT-8b in TAS, and there are several reviews in UK mags, all very enthusiastic. I encourage @hotrod6871 to consider the 8b ($3200) or 8c ($4500) before making a purchase.

@bdp24 I've owned Maggie's from MGIIIa's up to my current 20

1's. A friend of mine once owned a set of Acoustat Spectra 11's.  I was amazed how well they imaged compared to my then MGIIIa's.  The bass sucked, but the imaging was great. A few years ago I had the opportunity to get a set of Acoustat Spectra 33's and build on that. The larger panels and the seemless integration gave a much better sound over the 11's with increased imaging and bass response. I use a sub for the bottom end which helps with slam and SPL.  Do they sound better than the Maggie's,  no just different.  FYI: I don't need a sub for my Maggie's.

Enjoy the Music  

I heard the Sanders Model 10 ESL’s at two Stereophile shows, and considered the sound they produced to be the best at the shows. At one of the shows I also heard a gigantic pair of SoundLabs ESL’s, but there was definitely something wrong. Amplifier clipping?

The advantage ESLs have over other kinds of speakers is the fact that the Modus Operandi  of operation is powered. In a conventional speaker the voice coil moves when current is put through it in response to the magnetic field that is present. That magnetic field sags a bit when this happens,resulting in compression. In addition the voice heats up slightly with power, resulting in something called thermal compression.

ESLs don't have this problem so are one of the more dynamic speaker technologies out there. The real issue is driving them because they don't adhere to the Voltage rules which most speakers do. In that rule where the speaker is 'Voltage driven', its expected that the amp can behave as a Voltage source, which is to say it can put out the same Voltage regardless of the speaker load impedance.

ESLs have an impedance curve isn't based on a driver in a box. So there's no box resonance although there typically is an impedance peak in the bass region like many box speakers. But unlike box speakers they need to have power in that peak; in a box speaker this impedance peak is a resonance (a region of higher efficiency) so you want to throttle back the power so as to not play too much bass. If the amp behaves as a Voltage source then this happens.

So ESLs work better with amps that do not behave as a Voltage source. That's one of the reasons they can often work better with tubes. But ideally the tube amp should make constant power with respect to load and to do that the amp has to be either zero feedback or have equal amounts of Voltage and current feedback (which is rare; I don't think any such amps are in production today).  

Obviously this makes finding the ideal amp for an ESL a bit tricky. But once you have the right combination they can be pretty hard to beat at any price.

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.

The subject of Sub’s used with Quad ESL’s or a Tweeter to extend the upper frequency on 57’s is a widely discussed subject.

I have experienced Sub’s in use with a variety of Quad Models and a Super Tweeter in use with 57’s.

From a personal preference I find the additional Tweeter adds something that really appeals to me, ands would like to hear a Tweeter added as a Dipole Array to lift the higher frequencies.

I have detected on occasions that a added Bass is in use, from the experiences had, there does not seem to be the seamless integration into the produced end sound when the Bass is an added as a design being a typical Bass Driver set up. I am yet to experience a Dipole Array for Bass Drive Units being used.

Additionally, I have heard 57’s used with purpose produced Power Amplification that has been able to create the impression there is substantial Bass presentation , and the idea more lower frequency is required seems fleeting as an idea to be realised. I have even experienced others who have been demo'd such a set up, where some listeners have inquired which Sub Woofer is in use?

The Quad ESL (57) has been getting a bad rap for it's bass production for years. The speaker has quite good bass response down to 40 Hz. In most music, that would suffice. If you listen to rap/hip hop, electronic/dance, some of the newer movie soundtracks, and organ music, then the speaker will certainly not reach to those depths. The Quad ESL will even go below 40 Hz but at that point while the bass is still pleasing, it's more of the one not bass variety. I use a distributed bass array with two open baffle bass units next to the speakers and and additional two sealed boxes spread asymmetrically about the room. All bass drivers are 10", active crossover set to 100 Hz low and high pass with 24 dB slope. I use a Music Reference OTL-1 on the Quads and Bel Canto Ref 1000M monoblocks for the bass drivers. Works quite well.

I used several amps on Martin Logan Monolith IIIs in a 25X23X10.5 avg listening room with no power issues.  Audio Research Classic 60, Counterpoint 400, Bryston 4B.  However, my new wife had great issues with the terrible sound for rock, no bass, head in a vise dispersion for highs, lack of dynamic contrasts among others I forgot.  Dumped them for a pair of Legacy Focus and Signature IIIs (kept the latter).  We were happy for decades.