Which valve amp for quad esl63's?

S

soulman

Guest
I might have a bit of money free in the near future and am thinking if trying valves. My current amp has a warmer signature than many SS Amps I've heard or owned and want to see how a valve amp would work.

Any suggestions around the £600 mark that spring to mind? The modded AI S500 and puresound a30 both look ideal but which would suit best

 

wammer

Wammer
Wammer
Feb 26, 2009
1,481
8
0
HiFi Trade?
  1. No
I might have a bit of money free in the near future and am thinking if trying valves. My current amp has a warmer signature than many SS Amps I've heard or owned and want to see how a valve amp would work. Any suggestions around the £600 mark that spring to mind? The modded AI S500 and puresound a30 both look ideal but which would suit best
best amps are quad 405 405 mk2 606 909 valve quad mk2s

 

Tenson

Wammer
Wammer
Mar 2, 2006
407
2
0
I'd suggest the ESLs are best with solid state amps because you want low output impedance. Valve amps with higher output impedance will vary their response a lot with the impedance of the speaker. You are likely to hear some boomy bass with the high impedance spike at around 100Hz otherwise.

If you want to play with valves, why not use a nice SS power amp and a valve pre-amp?

 

RSand

Wammer
Wammer
Aug 25, 2012
691
16
48
Liverpool
AKA
Rob
Quad told me the quad II40's were the best to use with my 989's so I would guess something with similar specs ie around 40watts of kt88 power could work well?

 

Parkandbike

Super Wammer
Wammer
May 29, 2007
865
7
0
Cambridge
AKA
Don
HiFi Trade?
  1. No
Best amp I have heard with ESL63s and derivatives was a Berning ZH270. Unfortunately a bit out of your stated price range. The wammer who bought my 63s uses EAR amps and they were also very good with the 63s.

 

Valvebloke

Member
Wammer
Dec 3, 2009
4,439
272
128
Didcot, Oxon
AKA
Graeme
HiFi Trade?
  1. No
I'd suggest the ESLs are best with solid state amps because you want low output impedance. Valve amps with higher output impedance will vary their response a lot with the impedance of the speaker. You are likely to hear some boomy bass with the high impedance spike at around 100Hz otherwise. If you want to play with valves, why not use a nice SS power amp and a valve pre-amp?
Properly designed valve amps will have a low output impedance. Once it's less than about a tenth of the DC resistance of the speakers plus leads it won't matter anyway since that resistance will absolutely limit the maximum 'control' current which can flow no matter how good the amp is. Low output impedance comes when you apply a decent amount of feedback in the amp. When solid state amps were introduced they had to use loads of feedback to tame the inherent nonlinearities of the transistor circuitry. Low output impedance came as a by-product of this. So the marketing men latched onto it and made a big deal of this 'wonderful feature' of solid state. Just one more example of people being encouraged to pay for something which the manufacturers were going to have to deliver anyway and, in this case, which they didn't even really need.

VB

 

Gizza

Well-Known Wammer
Wammer
Mar 12, 2011
4,317
905
158
Sutton Coldfield
AKA
Gary
HiFi Trade?
  1. No
That'd be me - Hello again Don.

Yes, my EAR 509's work well with the 63's. Unfortunately they're well over the £600 pound limit here. As hinted at above, the 63's and later models have an impedance swing at frequency extremes, so an amp is required that can handle a 3ohm impedance. The speakers are also fairly innefficient, so at least 50w per channel is required with an active preamp. With a passive preamp, a minimum of 100w per channel from my experience. The more watts, the better, as it minimise amp clipping.

Best amp I have heard with ESL63s and derivatives was a Berning ZH270. Unfortunately a bit out of your stated price range. The wammer who bought my 63s uses EAR amps and they were also very good with the 63s.
 

Pussycat

Wammer
Wammer
Sep 9, 2008
1,716
25
78
Norwich
AKA
Mike
Best amp I have heard with ESL63s and derivatives was a Berning ZH270. Unfortunately a bit out of your stated price range. The wammer who bought my 63s uses EAR amps and they were also very good with the 63s.
Yes, I use E.A.R. mono's with my 2905s, but they equally made my 57s sing beforehand. Unfortunately, well out of your financial comfort zone again. Tim de Paravacini designed these amp's around the 63s.

 

It Cost How Much!?!

Twisted
Wammer
Oct 27, 2008
16,903
1,524
173
Hartford, Cheshire
AKA
Bob
HiFi Trade?
  1. No
Yes, I use E.A.R. mono's with my 2905s, but they equally made my 57s sing beforehand. Unfortunately, well out of your financial comfort zone again. Tim de Paravacini designed these amp's around the 63s 57s.
TdP likes 57's, he once gave me a lecture about how shite my speakers were compared to 57's.

 

Gizza

Well-Known Wammer
Wammer
Mar 12, 2011
4,317
905
158
Sutton Coldfield
AKA
Gary
HiFi Trade?
  1. No
I reckon that with a limit of £600, you're not going to find a valve amp that will drive the Quads well. As suggested above, perhaps a valve pre with a decent S/S power amp. Does anyone know whether Quad power amps work with a valve pre?

It does raise the question though of why you want to move to valves? Going to a high powered S/S should avoid the harshness of S/S clipping. The articles on Roger Sanders' Innersounds website looks at this subject in detail. Very informative reading and not over-technical.

 

Martha's dad

Now Milly's dad
Wammer
Jun 2, 2007
2,635
93
93
Overstrand
AKA
Papa du chien
HiFi Trade?
  1. No
Best amp I have ever heard with ESL63 - easy - Tube Tech Synergy - but afraid again way above your budget.

Alernatively Quad 909 with a good preamp

 
S

soulman

Guest
I don't know much, if anything, if the technical side of hifi, i was wondering if it was possible to get a valve amp that would better the Sony without spendinga fortune. I like the warmth of he sound but want a bit more excitement. It's to try a different flavour as much as anything.

Mayb look at some SS options as well, didnt like the Quad 77 as much as the sony, lacked bass and soundstage

 

Tenson

Wammer
Wammer
Mar 2, 2006
407
2
0
Properly designed valve amps will have a low output impedance. Once it's less than about a tenth of the DC resistance of the speakers plus leads it won't matter anyway since that resistance will absolutely limit the maximum 'control' current which can flow no matter how good the amp is. Low output impedance comes when you apply a decent amount of feedback in the amp. When solid state amps were introduced they had to use loads of feedback to tame the inherent nonlinearities of the transistor circuitry. Low output impedance came as a by-product of this. So the marketing men latched onto it and made a big deal of this 'wonderful feature' of solid state. Just one more example of people being encouraged to pay for something which the manufacturers were going to have to deliver anyway and, in this case, which they didn't even really need.VB
The thing to consider is not just 'grip and control' of the speaker, but how the FR changes with large impedance swings. Yes valve amps can have low output Z but many don't. It's hard to apply a lot of feedback at frequency extremes around a transformer coupled output. Most output Z is often rated at 1KHz which may be where many box speakers have the crossover impedance swings but the ESL63 doesn't. The ESL63 has swings at 100Hz and in the top-end treble.

Basically with an amp that might have say 2-4 ohms output Z at FR extremes you will hear more bass at 100Hz and more treble >10KHz compared with a low output Z amp (I guess) like the Sony already in use.

So the point is consider if you want more bass and treble. Then make sure your amp either has or doesn't have high'ish output Z.

 

Pussycat

Wammer
Wammer
Sep 9, 2008
1,716
25
78
Norwich
AKA
Mike
TdP likes 57's, he once gave me a lecture about how shite my speakers were compared to 57's.
I'm sure he did, but the 63s were the speakers he designed the 509s around; at least, that's what he told me a couple of months ago. We all have memory loss, though.......!

 

Valvebloke

Member
Wammer
Dec 3, 2009
4,439
272
128
Didcot, Oxon
AKA
Graeme
HiFi Trade?
  1. No
The thing to consider is not just 'grip and control' of the speaker, but how the FR changes with large impedance swings. Yes valve amps can have low output Z but many don't. It's hard to apply a lot of feedback at frequency extremes around a transformer coupled output. Most output Z is often rated at 1KHz which may be where many box speakers have the crossover impedance swings but the ESL63 doesn't. The ESL63 has swings at 100Hz and in the top-end treble. Basically with an amp that might have say 2-4 ohms output Z at FR extremes you will hear more bass at 100Hz and more treble >10KHz compared with a low output Z amp (I guess) like the Sony already in use.

So the point is consider if you want more bass and treble. Then make sure your amp either has or doesn't have high'ish output Z.
I confess I don't know enough about the impedance curve of the ESL63 to say specifically what the impact on overall FR of an amp with a high output impedance might be*. Like you, I recommended to the OP that he should find an amp which doesn't have a high output impedance. While I agree it is perfectly possible to make a bad valve amp, I still don't think it's inevitable. A while back I made some measurements on my Radford STA15 and IIRC its output impedance was about 0.15 ohms, which is negligible. I would certainly have measured that at mid-frequencies. But since my measurement setup could easily cover the full audio frequency range I might well have checked it out in the bass and the treble too. When I get the chance I'll see if I can track down the raw results. But as I recall the feedback is not rolled off artificially in the bass. So as long as the amp's output remains at its mid-frequency level I think the output impedance must too, mustn't it ? (Then again, what would the effect of any phase-shift be ... hmmm ?) Maybe it's worth bearing in mind that the ESL57 was specifically designed to be used with a valve amp (the Quad II) and also that when the design for the ESL63 started Quad were still not making solid-state amps. So I'd be surprised if the match between valve amps and Quad ESLs was inherently a bad one.

VB

*The only curve I have for the ESL63 shows the impedance modulus as a function of frequency. This does indeed rise below 200Hz (a great deal, depending on the signal level) and above 10kHz (rather less). But whether this will lead to higher audio output from an iffy amp will depend on what fraction of the speaker impedance is resistive and what reactive and then, in addition, on what fraction of the resistive component is associated with the production of sound and what fraction simply comes from non-audio losses (ohmic heating, magnetic core losses etc). Without knowing all these details I'd just be guessing I'm afraid.

 

Tenson

Wammer
Wammer
Mar 2, 2006
407
2
0
Yeah phase shift is the killer for feedback at frequency extremes in a transformer coupled output design. It will of course depend greatly on the transformer.

This is the ESL63 impedance curve. The bass peak is pretty huge. The top end goes quite low.

I realise now I made a mistake, a high output Z amp will have more bass but less treble. As the output impedance approaches the load impedance it becomes less of a voltage source and more a current source. So a high impedance load will receive more power than it would from a near perfect voltage source. Also lower impedance will get less power than it would from a voltage source. If you had an amp with 2-ohm output impedance it would give you a very noticeable top end roll-off with the ESL63.

QUADFIG1.jpg


 

Valvebloke

Member
Wammer
Dec 3, 2009
4,439
272
128
Didcot, Oxon
AKA
Graeme
HiFi Trade?
  1. No
Yeah phase shift is the killer for feedback at frequency extremes in a transformer coupled output design ...
It certainly is in terms of stability. And that's the major problem that circuit designers seem to struggle with when it comes to feedback. I'm less clear what effect it has on output impedance though.

I've got an original Quad ESL63 service data book here and they also give an impedance curve. It's similar to the Stereophile one although the LF resonance peak is less sharp and is shifted further into the bass. They do point out that it's just the modulus though.

I realise now I made a mistake, a high output Z amp will have more bass but less treble ...
OK, I just assumed you were looking at the impedance peak at 22kHz. The sort of people who worry about the last few milliohms of output impedance tend also to be the sort of people who are convinced they can hear up there :D .

VB

 

RobHolt

Wammer
Wammer
Aug 28, 2006
942
30
0
East London
AKA
Rob
I wouldn't worry about the peaking up at 22kHz.

Worry about the relative change between the 100Hz area and the 10kHz area which is around 30 Ohms.

Effectively this will sound like rotating a Quad tilt control a couple of notches clockwise.

From personal experience with trying lots of amplifiers on 63s, 50wpc is a practical minimum given sensitivity is in the low-mid 80s.

Trying a good 25 watter recently (a Marantz which Tenson will remember) it was possible to get decently loud but there was virtually no headroom and it was easy to hit clipping.

50w for a small-medium room if you're not a head banger, 100w for everything else.

More than 100w is fine of course but the 63s can't use this extra capacity and will respond by sounding like they are about to fall apart!

...which they probably are since they are deliberately built to be mechanically lossy in the frame :)

 

Forum statistics

Threads
109,191
Messages
2,314,135
Members
69,422
Latest member
Creedy