mhardy6647
Lunatic Member
or this (these):
QUAD ESL-57's destroyed a Carver TFM-55x amplifier
- Thread starter kve777
- Start date
Long ago and far away, I had stacked-Quads — two per side. In fact I had a pair of stacked-Quads, a total of 8. And each was driven by its own perfectly-matched Quad II, the amp pictured above. This was in Cape Town, when "valves" were considered "obsolete" and people were selling them for peanuts, with their original tubes and plenty of NIB spares, as they rushed to Linn and Naim.
The system was all-electrostatic and the most ec-static I've ever heard. But I had to move back to US, and sold it all piece by piece, because the packing and shipping costs were so high. I regret it every day.
A Therapist told me I should "never regret anything in life, it's not healthy."
"You never had stacked Quads," I replied...
mhardy6647
Lunatic Member
RobHolt
Active Member
I have ESL57s and 63s. The former require an amplifier to be unconditionally stable.
Neither Quad pulls much current since while the impedance does fall below 2 ohms, it right out at the audio range extremes where power demands are small.
However they do present a capacitive load and this can induce instability is some amplifiers. They oscillate and rapidly fail.
To illustrate the point about stability over current capability as the key factor, one of the best amplifiers in my collection for the ESL57 is the little Pioneer SA500A from 1972. A capacitor coupled, super simple amplifier rated at 13wpc.
Neither Quad pulls much current since while the impedance does fall below 2 ohms, it right out at the audio range extremes where power demands are small.
However they do present a capacitive load and this can induce instability is some amplifiers. They oscillate and rapidly fail.
To illustrate the point about stability over current capability as the key factor, one of the best amplifiers in my collection for the ESL57 is the little Pioneer SA500A from 1972. A capacitor coupled, super simple amplifier rated at 13wpc.
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RobHolt
Active Member
Only if modest sound levels are required, perhaps in a small room with near-field listening. Within the volume constraints it sounds fine though. The little SA500A is a very sweet little amp.
IME the 63 needs a minimum of 50w and preferably 100w to let them go loud and stay clean.
Quad recommended 100W for the ESL63, and released the 405 power amp at the same time. It was specifically designed to optimize the ESL63 — it was not "general purpose" and didn't sound as good with conventional speakers. Quad then released the 405–2, a more conventional version of the 405 for other speakers.
Have you noticed that of some amps have a small open coil, sometimes marked on a diagram as a low value resistor, fitted just before the speaker terminals? Ever wondered what that is for? Some people remove these thinking that they affect sound quality!
It's there to prevent parasitic output stage oscillation into capacitive loads, and is often combined with a small cap and resister to ground forming a zobel network. A capacitive load can (and quite often does) form a resonant filter with the emitter resistors through the output transistors forming a parasitic oscillator with positive feedback. If this starts it will very quickly spiral out of control in a few milliseconds. If you are lucky, a full electronic protection system (one which measures output overload as well as extreme DC offset) may just catch it. Fuses definitely will not.
It's there to prevent parasitic output stage oscillation into capacitive loads, and is often combined with a small cap and resister to ground forming a zobel network. A capacitive load can (and quite often does) form a resonant filter with the emitter resistors through the output transistors forming a parasitic oscillator with positive feedback. If this starts it will very quickly spiral out of control in a few milliseconds. If you are lucky, a full electronic protection system (one which measures output overload as well as extreme DC offset) may just catch it. Fuses definitely will not.
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slimecity
Super Member
I sold a guy my Pioneer M22 amplifier after he became convinced that it would run a set of his quads.
And...he was right...so far. When he told me this I warned him to get some good info on whether the pairing would work out. But he insisted, based on a recommendation from Ken Kesler apparently.
It runs and sounds fine.
And...he was right...so far. When he told me this I warned him to get some good info on whether the pairing would work out. But he insisted, based on a recommendation from Ken Kesler apparently.
It runs and sounds fine.
MudSlideSlim
Well-Known Member
I agree with what your sayin the 405-2 works very well with lots of speakers.
In my younger days I'd hang out at a HiFi shop and the Quad 405-2 amp was the best amp going on there in its price/watts/current range. It worked surprisingly well with a wide range of speakers but really sang with Spendors.
That being said a 35 watt tube amp (ST70) worked even better with ESL as well as LS35A speakers.
