The Shure V15 V with a Jico SAS/B stylus VS The Soundsmith Hyperion MR and Lyra Atlas SL

@lewm See, you learn something everyday. I've still blown out more Quads than you:-) We both own extremely similar loudspeakers, I suspect for a reason. Acoustat 2+2s driven by one big transformer and crossed to subwoofers at 100 Hz sound exactly like our speakers except their horizontal dispersion is worse.....much worse. I also believe it is the job of the step up transformer to convert current to voltage. IMHE, and we both use OTL amps, the amps that drive ESLs best are SS amps with HUGE power supplies. For whatever reason, the Bricasti M28's do a better job of it than the MA2s. I like the MA2's midbass better, but I tend to push them hard the result being a steady drain on my tube supply. They are great amps suited to a less stressful existence. The Bricasti amps are the most bullet proof amps I have ever used. If they do not like something they simply turn themselves off. Reboot them and you are good to go. They also are amazing at protecting loudspeakers. If they detect any clipping either their own or any other unit in the chain they turn themselves off immediately and this includes digital clipping. I burned out two transformers clipping the MA2s.  I do believe Acoustat was the first to curve an ESL in the horizontal plain. The X which came out in 1978 had three panels angled about 15 degrees to each other giving a horizontal dispersion of 30 degrees. The 2's and the 2+2's only had 15 degrees of horizontal dispersion, but it was better than 0 degrees (at high frequencies)

@rauliruegas You are correct! The Digital Drive Plus series has a high pass filter.....a 1st order one. Definitely better than nothing...if it is being used. I use a digital 8th order filter on both low and high pass sides. @richardbrand are you using the high pass filter??  I agree that Roger West could have stated that position more accurately. Dr West did advance the art of ESLs. ALL dynamic drivers are point sources unless you stack them in a linear array with the right spacing between drivers and that has never worked well in home HiFi systems. It has been tried unsuccessfully 3 or 4 times by Infinity, Nearfield and others. This results in a big impressive sound lacking in fine detail and image specificity. Most line sources, like Maggies, Apogees and many ESLs are crippled because they are not tall enough to extend the line source behavior below about 250 Hz. A proper residential line source has to extend from floor to ceiling or it loses it's line source behavior at the frequency matching the wavelength of the speaker's height. The power projection stops at the frequencies it is most needed. Now, what you are talking about is a co-axial point source which has absolutely no advantage over non co-axial point source speakers that are spaced closely together until you are a foot from the loudspeaker. In doing the variable diameter point source Quad was trying to improve dispersion characteristics at high frequencies. My assessment of modern Quads is there are dynamic speakers that outperform them in many ways resulting in a better listening experience particularly at levels above 85 dB. 

Funny how coincidences happen. As i read this, I was going through a box of interconnects and found two unused Shure V15-IV MRs. I was given when I worked at a studio. We had purchased several of the "new" Shure CD players for doing transcription work and they came with these carts. Just wondering, my bedroom system has a Music Hall classic w/an Ortofon 2M Bronze that has around 250 hrs on it. Does anyone have an option if the Shure may be a worthwhile replacement? 

This thread has evolved as if the Shure V15 was the sine qua non of vintage high output cartridges. It’s surely not that, in my experienced opinion. Far from it. But if you try it, give an NOS cartridge that must be minimal 30 years old at least several hours playing time before you judge

Mijostyn, if you’re talking about the Sound Lab OEM backplate on a Sound Lab speaker, with its power robbing parallel resistance and its very low midrange impedance, then yes perhaps an SS amplifier is better suited to overcome those handicaps. But if you want best sound, you remove those kludges, then Z and efficiency go way up and an OTL kicks ass. If you don’t agree, that’s fine, but please stop telling me what I would like.

To add a bit to the ESL plus OTL paradigm, Sound Lab, by using two audio step up transformers, one for bass and one for treble, and by therefore using a passive crossover between them, are somewhat unique in spoiling the natural match of ESLs to OTLs, because of that midrange impedance dip thus incurred. Scuttlebutt was and is that SL use solid state amplifiers (Parasound JC1s, it is said) to voice the speaker and so are ignoring the problem, essentially, for tube aficionados.  Historically, ESLs like Quad, KLH9, Jantszen, Acoustat, original CLS by M-L were high impedance speakers well suited to OTLs.  Then M-L revised the CLS (which came to be known as CLS II) such that impedance was lowered considerably, to suit the rising popularity of SS amplifiers, I guess.  I traded in my beloved CLSs for the CLS II on account of the favorable publicity but without knowing what M-L had done to the impedance curve; the CLS II sounded awful with my Futterman OTLs. Sound Lab "borrowed" the two transformer idea from Acoustat, actually, in the 90s.  So I don't know when Acoustat were driven via only one step-up transformer as you mention.  The earliest Acoustat I recall was the Acoustat X, a giant panel that was direct driven by an on-board amplifier, which I heard once but cannot remember aurally.  That was in the mid to late 70s.

richardbrand, Though no one ever told me this, it was my assumption that the Quad 57 is curved in the vertical plane, because it was designed to sit only a few inches off the floor.  So they devised a stand that leans the speaker back a bit to tilt it upward, and to further enhance radiation to the height of a listener's ears, they curved the panel.  I imagine that all this was to accommodate the smaller listening spaces of typical UK houses and apartments.  They never dreamed of stacked pairs as part of the original design intent.  I would guess that the last thing anyone thought about was how the vertical curve would focus the rear radiation. 

Also, now I think of it, you are probably correct.  The 1963 speaker was called "ESL63".  It falls trippingly from the tongue.  The ESL63 is the only Quad speaker I ever owned. I didn't love it as much as some others. I just don't recall the 1957 speaker being referred to as ESL57, but if you say so....

@richardbrand   : " old enough to have a pulp/paper cone but if the servo mechanism is good enough, who cares?   "

It cares any one that knows in deep about best bass range build material subs, not all material gives us the same bass quality level.

Btw, my Velodyne's came with the servos too as yours.

R.