Attenuation with a passive pre !

[Tony L]

FWIW it seems, from my experience, to be a lottery which speakers will or won't work with the ST20. I think it has much more to do with the impedance curve than sensitivity, otherwise how would the they ever work with 83dB LS3/5As?

The LS3/5A is a tiny little mini-monitor designed for near-field listening. It is only rated at “25 Watts music and speech”, i.e. that isn’t an RMS rating. Give it more than about 10 or 15 Watts at the right frequency and you’ll slam the B110 into the voice-coil magnet. Similarly you can bottom-out a pair of Kans with a 12 Watt Nait. The LS3/5As have a nice easy high impedance which valve amps like so it all holds together well. In a near-field scenario the system works well. Want louder or further away just buy bigger speakers regardless of the amp. The Leaks can drive either the LS3/5A or JR149 louder than I would ever personally want to listen to a speaker in that size category. Give me a 200 Watt Krell and I’d not push them any harder.

The Leaks do very well with the original ESL too, again a nominally 16 Ohm loudspeaker.

ProAcs are always a good match with valves. As I understand it Stewart Tyler used and designed with valves, I think Audio Research, which is typically more powerful than a Leak, but I’m sure the Stereo 20 will do well in that company. A genuinely good 10 Watts goes a long way, especially as you can optimise the impedance for the speaker.

 

[Tim Jones]

I challenge anyone to find a better £1k amplifier if you have an Allegri in a barn and vaguely sensible speakers. Also, it can be kept running and will gain value.

Actually, and while I've only heard one half of this equation, Exhibit A is the Pass Aleph 3. Solid state, SE, Class A, low power. I've been running this either with an excellent Primare Pre32 (which has the huge advantage of adjustable gain), or with the Allegri (which just sounds incredible). My instinct is to stick rather than twist, given how much I am enjoying the Aleph; and it seems to get on well with my ProAc DB1s. I keep meaning to try it with the LS50s.

The only person qualified to comment on a choice between a Stereo 20 and an Aleph in these parts is probably Tony.

 

[foxwelljsly]

Will have an ST20 for sale soon...

FWIW it seems, from my experience, to be a lottery which speakers will or won't work with the ST20. I think it has much more to do with the impedance curve than sensitivity, otherwise how would the they ever work with 83dB LS3/5As?

The only speakers I've owned that definitely didn't work were Amphion Argon 1's & Argon 3S's. Just sounded flat & lifeless which was a shame because otherwise the Argon 1's in particular were superb with the SS amps I owned, one of my favourite speakers.

TS

I can tell you that a well sorted pair of Kef 104/2s and a Stereo 20 are a match made in hi fi heaven. The Kefs use something called conjugate load matching to present as 4r resistor to the amp and are 92dB. They sound sweetest off the 8r tap and can go surprisingly loud. They are ludicrously common, can be bought for peanuts and are very conservable/restorable. They are a bit big, though. They’re also the speakers from ‘that’ scene in American Psycho, although I don’t think Patrick Bateman had a Leak. And I hate Huey Lewis and the News.

My titchy AVI Neutrons also sound great, although at 83dB, they are very much a nearfield speaker with a Stereo 20.

 

[Tony L]

The only person qualified to comment on a choice between a Stereo 20 and an Aleph in these parts is probably Tony.

The amusing thing is in a sighted dem I guarantee most people would pick the opposite amp to what was playing. To my ears the Pass had a very gentle, clean and 3d sound, exceptionally well behaved. The Leak is a party animal, it just rocks like the best Naims, but without any of the edge or thinness. I’m exaggerating to make the point, but the Leaks are definitely more ‘up for it’. That said my experience may be flawed as I don’t think the Pass liked my Verdier valve pre much (more of the same traits) and the Audio Synthesis ProPassion passive may not have been ideal either.

I was also comparing against a pair of TL-12 Plus, not a Stereo 20, but they are very similar. I’d have very much liked to hear the Pass with a Pass, Threshold, Krell, Mark Levinson type preamp as I think that is what it needed to wake it up, but here the AS passive and Leaks were a long way ahead. I suspect it just didn’t like my kit. That said with the AS passive pre and JR149s it did some pretty stunning things. That was where it worked best by far. It wasn’t right in the Tannoy system at all (which likes Leaks or the 303).

 

[Alex S]

Pipe and slippers the Leak ain’t.

 

[Mike1965]

Years ago I heard an Aleph 3 into Sonus Faber Amati's at a friends house with its own preamp (the Aleph P) and it was as clean and detailed as Tony says but I thought it was disappointing.

 

[Tony L]

Years ago I heard an Aleph 3 into Sonus Faber Amati's at a friends house with its own preamp (the Aleph P) and it was as clean and detailed as Tony says but I thought it was disappointing.

It is a really hard one to call. I got a good taste of what it could do with the 149s. Once up to temperature (it does like to be warm) it has incredibly natural timbre and casts a very believable 3d soundstage, and it wasn’t lacking in dynamics, but there was still a little restraint somehow. The thing I found the most odd was the extent to which it didn’t suit my Lockwoods. The humble Quad 303 just destroyed it in that specific context (between my Verdier pre and the Lockwoods). I’m just pleased I heard it with the 149s and LS3/5As as well as otherwise I’d have written it off. As it is I really liked it. The 149s are amazing at imaging and sounding far bigger than they have any right to, and the Pass really worked to their strengths, especially with classical and jazz, though really good all round really. It is a very good amp. I’d be curious to see what it could do into Quads or Maggies.

 

[Tim Jones]

It's one of the best components I've ever heard. I first tried it with a cheapo Tisbury, with the 3V output from the Qutest, and I couldn't stop listening.

The Allegri is better with line sources, but the Pass really needs something active to work with vinyl. As I've mentioned before, the matching Pass pre-amp has L/R gain and a "master" volume, but I've only ever seen a 110V version, located in Tokyo.

It's my daily driver now, but I have more to do to get it to an ideal place.

I mean, I'm not ruling out a Leak, but at this rate I'll have five different amps. One worry is whether there is anything below (say) 100Hz. If I have one holdover from the big Naim system days, it is a fondness for something approaching bass.

 

[Mike1965]

It's one of the best components I've ever heard. I first tried it with a cheapo Tisbury, with the 3V output from the Qutest, and I couldn't stop listening.

The Allegri is better with line sources, but the Pass really needs something active to work with vinyl. As I've mentioned before, the matching Pass pre-amp has L/R gain and a "master" volume, but I've only ever seen a 110V version, located in Tokyo.

It's my daily driver now, but I have more to do to get it to an ideal place.

I mean, I'm not ruling out a Leak, but at this rate I'll have five different amps. One worry is whether there is anything below (say) 100Hz. If I have one holdover from the big Naim system days, it is a fondness for something approaching bass.

Maybe the Aleph does benefit from a higher output from the source?

 

[Mike1965]

I have only heard a Leak Stereo 20 once and it's a fine sounding amp. I would like to hear one again sometime. It carries a tune for sure.

 

[Mike Hughes]

I have followed several of the Leak Stereo 20 threads with increasing fascination thus my interest in the English Acoustics update but I’ve never heard an actual Stereo 20.Very long shot but I don’t suppose there‘s anyone in the GM area accessible by public transport who would be willing to let me have a listen for a couple of hours?

 

[karlsushi]

I've been a Pass Aleph 3 owner for a few years and have loved every minute of it. Having tried it with LS3/5As though, I'm not convinced that is the right pairing. My instinct is that this has something to do with the high impedance of the LS3/5A, with the SS Class A topology of the Pass much happier doubling down into 4 and even 2 Ohm loads.

Works beautifully with my 89dB 8 Ohm Wilmslow LS3s which I use without a pre (DAC with either analogue or digital internal volume control).

A beautiful smooth presentation with plenty of natural detail. I have a 303 too and to my ears, that has never come close to the A3, especially in terms of 3D and imaging.

Having said all this though, I have recently taken the plunge and gone all valve in both systems. The money would be useful, but I don't think I'll be selling it. One of those amps that I expect I would regret selling, even if it just lives in the loft.