Jadis JA30 - Quad ESL63 .. 4,8 or 16ohms?

Curio
You will have to borrow a pair of Atma-Sphere amplifiers to try with the Quads.

Natural sounding vocals are very high on my list.

With good recordings the illusion of a physical presence in the room is startling with the Atma Speres amps.
I used the Atma Sphere M60s with a refurbished pair of Quad 63s for a few years.

Tenor OTL amps I have also heard on the Quad 57s, just astounding.

Years ago the late Harvey Rosenburg bought the rights to the Futterman Otl amplfiers, re-worked the amp and used them exclusively on the Quads.

Thanks Stilskin!

You can't believe how much me and Giorgio are curious to try a OTL amp on the Quad ESL63s
Unfortunately we don't have any Atmasphere or Tenor Audio dealer around here to ask for a borrowing :-(

The Quad 63 has always been a great match with our M-60 and MA-1 amplifiers. The speaker has an impedance peak in the bass that is well over 40 ohms and many amplifiers, especially transistors, don't make a lot of power at that impedance. OTLs, OTOH, once you get above a certain impedance (depending on the size of the OTL) will exhibit a sort of 'constant power' characteristic, so their output power does not drop significantly in the bass.

Unlike a lot of box speakers, the Quad's impedance curve has nothing to do with either crossovers or resonant peaks. It has mostly to do with the inductance of the matching transformer and the capacitance of the panel. The result is that a constant power characteristic in the amplifier is desirable if you want to get the most out of the speaker.

see
http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.

With transformer-coupled tube amps, the trick is a moderate-powered amplifier that does not use a lot of negative feedback, usually set on the 8 ohm tap. With an OTL of course, you just hook it up. Since the 1950s, Quads and OTLs have always been the ideal match. The speaker is quite transparent and getting rid of the output transformer is very noticeable! Later Quads seem to be following the same path as Martin-Logan, by having very low impedances, in order to get them to work with transistors, but IMO/IME this tack never works- if you really use it with transistors it will be too bright and no bass. IOW tubes are still the ideal method with newer ESL designs but you have to use a set of ZEROs (http://www.zeroimpedance.com) to make them work.

Ralph,
Will Quad 57s match well with the M-60s or for that matter the M-30?
The impedance of the the 57s is all over the place.

Curio and Giorgio
You want a good taste of musical Heaven in your home?

I would most definitely buy the Atma-Sphere monos for your Quads....

Mark