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Dear Friends,I have been struggling for a long time looking for a decent amp for my quads. I ended up with a solid state as the valve amp I had was not too dependable and from where I write (Italy) to have it serviced was almost unfeasible.
I am not happy with the sound of the solid state amp (probably my taste) so I would like to switch back to tubes. Here comes the trouble, as I really find it very confusing to choose one.
Obviously my ears will decide which one to pick, but there are some technical issues I would like to know more, as I am afraid that the wrong amp will maybe give me a good sound but with a poor dependability.
Some of the dealers I have met are telling me that OTL amps are the best pick for my quads. Some others are telling me exaclty the opposite, claiming that the features of my speakers (that I will not change for my lifetime) are demanding a completely different amplification.
Here comes the first question.
Is there any amp design I should avoid from the technical point of view, leaving aside sound quality consideration?Another issue is amount of watt. Some are claiming that at least 60W are needed, others that 15 W will be more than enough. Once again I am very confused. I do not listen loudly to the music, but I am afraid that pushing too much an amp will shorten its life.
Here the second question.
What is in your opinion, once again from the technical point of view and leaving aside all sound quality consideration, the minimal wattage needed to drive decently and without loosing tube life my Quads (non particularly efficient equipment)?Please note that I am sure I will be able to pick what will be suitable for my taste in terms of sound. But I would like to know if there is something I must exclude from a technical standpoint. Excuse me for my very naive questions but I am totally ignoring anything about how an amp works. I switch it on and I listen and I imagine there are inside some little elfs amplifying the signal...
thank you in advance for your precious help and for your time
Alberto
Follow Ups:
I hooked up the Berning ZH-270 with my lovely Crosby mod ESL-63 back to 1997. This is the best amplifiers I have came across on this particular loudspeakers.
The ESL 63 likes a bit of power. 60 watts is adequate (depending on room size), for the most part 120 watts is near the max that the speaker will take before the protection circuit activates. Because of the power considerations, SE triode amps are right out in all but the smallest rooms and then only on the ESL 57s ('old' Quads).Transistors don't do so well on the speaker. The impedance in the bass is too high and the transistor amp will be bass shy and also bright on top. Transistor owners thus tend to have the speaker too close to the rear wall usually wind up with 'one note' bass. It is common that if they graduate to tubes, complaints of boomy bass manifest until they get the placement issue (5-6 feet from rear wall) sorted out. This distance is the norm for all planar speakers BTW.
So you have to use tubes for best results. The impedance curve presents a problem to transformer coupled amp, however. The impedance can go quite high, causing a transformer in a tube amp to ring, even if used on the 16 ohm tap. The resulting distortion tends to muddy the sound.
This is why OTLs have been the traditional favorite for Quads since the speaker was developed back in the 50s. Quads generally have a relatively benign load for OTLs even at 20KHz (relative to some other ESLs) and as a result an OTL will often produce better highs then either a transformer coupled amp (more extended and lucid) or a transistor amp (lacking the piercing highs of transistors).
Have fun! and obey your ears.
I agree with Ralph that (his) OTLs sound wonderful on both 57s and 63s. But the 63 do not have the same impedence curve as most electrostats and are actually more uniform than many dynamic speakers eg, early Spendors, certain B&Ws, which have their own anomalies. I repeat that a PAss Aleph is a great choice if you require a low maintenance transistor amp, perhaps it is an exception that makes the rule?
Alberto,if you can get one then look and buy an old QuadII amp. Quad is also producing an new version of it with 40W - and it is a good partner for it.
If you will make a DIY then try out a 211SE or an clone of the Brook amps.
http://www.quad-hifi.co.uk/
http://www.quad-musik.de/
Ciao
Joao
One of the Pass amps, perhaps. I've been running the Aleph 30 in my bedroom system. Excellent amp!
Alberto,
Use a tube amp for best results. OTL is the best but many times unreliable. Push Pull tube amps would be the second best and you need15 watts or more. Stay away from single ended with these speakers as you will get a very colored sound do to the impedance curve of the ESL. When looking for a PP amp try to go with EL84's or EL34's as these tubes seem to suit the ESL well.
Good luck on your search and I hope this helps.Jonathan
The 63s, unlike most other ESLs, have a benign impedence curve, by design, of nominally 6 ohms.The problem with many tube amps on 63s, eg, early Quicksilvers, is that they make everything pleasant or alike, depending on what your point of view is. If that is the kind of sound you like, IYMV.
Ivan,
Sorry to disagree but the impedance curve is fairly severe. Here is a copy of the plot:
http://user.tninet.se/~vhw129w/mt_audio_design/images/quad63_impedance.jpgJonathan
wasn't this fixed in us monitor version?
The very best amp that I tried on my crosby-mod'ed ESL 63's
was the New York Audio Labs OTL 4.I still have the quads and NYAL amp packed away, in case I want to revisit that sound.
I was owner of Quads during several years and the best combo that I knew was with an ATM-2 of AIR-TIGHT (2X80W).I think it's necessary
to put many Watts (2X150 would be better )to obtain good bass .
With ATM-2 it's was "magic" !!!!!
Well, are you looking into vintage or modern gear??I can't comment too much on modern gear, I'm an old fart...:-)
However, I CAN tell you that a pair of well restored Quad IIs will drive these puppies into insane volume levels, as will any of the US brethren, like the Scott 299 B/C, Fisher etc. whatever you fancy...
However, my first choice would be the German made Klein & Hummel amplifiers, as these are specifically suited to drive ESLs. The famous German Braun, Saba and Telefunken companies used to sell modified versions of the K&H amplifiers, allowing connections to ESLs, and boy, do they sound sweet. They attributed to the very pinnacle of German made hi-fi tube designs. In fact Braun even did distribute ESLs under their own branding!
If you need more info, just let me know.
/Dieter
The best amp I used with my 63s was a Pass Aleph 5, 60 wpc class A. I'm sure the larger mono amps would do better.I think 15 watts is a bit low. I tried a pair of SE tube amps 18 watts and they did not have adequate sound.
The best I have heard quads is with believe it or not the 47 labs 25W Gaincard amplifier.. amazingly coherent and musical sound.
The Scott 299(a) also works magic with this amp.
But you'll probably end up with some amusical brute but give this a try it is really really good.
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