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Leak Stereo 20 versus current valve amplifiers?

Junaman

pfm Member
I am looking to foray into tube amplifiers. I have owned Allnic and Remton valve phono stages, but never a valve pre, power or integrated. Looking for advice on a tube amp for a medium sized room.

My vision is of curling up on the sofa with Junawoman, a bottle of wine and some late night jazz, acoustic or vocals music. My main system is for rock and full scale orchestra, so this is for a second system which is all about capturing the mood of the music and doesn’t require volume levels that will blow us out the room.

My speakers are relatively sensitive at 91 dB and sources would be my Ariston RD11 turntable and streaming through a bluesound node2i and Rega DAC-R. I have a spare phono stage at the moment, a Remton 383 MKII, but could go with an integral phono stage in the amp to reduce box count.

I would be looking to buy pre-loved and have a budget up to £1500. There are some well reviewed amps from Unison Research, Primaluna and Icon Audio available just now in that ballpark, e.g. Unison Research Simply Italy, Icon Audio Stereo 30SE, etc. On the other hand I am very tempted to go down a vintage route and have been reading up about Radford, Quad and Leak. I don’t think I have room for monos, so looking at a stereo version. My initial thought is a Leak Stereo 20. Plan would be to buy a decent condition one and the get it refurbished by Classique or Servicesound. Then pair it with a modern passive pre like the Tilsbury II.

My question, which I suspect is a perennial favourite, is which would be better a modern valve tube or a vintage? Anyone have experience listening to both types? Looking forward to hearing your views.
 
My question, which I suspect is a perennial favourite, is which would be better a modern valve tube or a vintage? Anyone have experience listening to both types? Looking forward to hearing your views.

I’ve owned a Leak Stereo 20 for quite a while now, and mine is rebuilt very similarly to the way Classique Sounds do it (i.e. as close to original spec as possible). Obviously many people rebuild Leaks in all manner of different ways, many ending up a totally different item at the end, so no longer a Leak in any real sense. In restored standard form it’s a stunning EL84 amp IMO. Surprisingly powerful, coherent, fun and spacious, mine doesn’t put a foot wrong sonically to my ears. I really like it (and the very similar TL12 Plus mono amps).

The next question is what exactly is its competition? With a bit of luck you should be able to find a decent Stereo 20 and get a Classique-grade restoration in for £1-1.2k, maybe less if you are lucky in buying. I can’t think of anything much available for less that will beat it sonically. The first contender that comes to mind is the Leben CS300, which is a lovely little amp, but my hunch is the Leaks have better output transformers and more heft, though I’ve never had them in the same room. There is some decent Chinese stuff, e.g. Prima Luna, but I’m sure I prefer my Leaks to my old Prologue 2, though we are comparing EL84s to 34s or KT88s here, and how much power you need comes into play. Next contender is obviously Radford, but you are in a different price class here (the new ones are very fairly priced IMO). Quad IIs are obviously a contender too, but they cost more to feed than a Stereo 20 and I’m not convinced they have any advantages.

One of the advantages of the Stereo 20/TL12 Plus is thanks to the Russian military there is still a supply of very good EL84 type valves in the 6p14p-EV or ER types. Good rectifiers are bloody expensive though. If you do decide to try a Leak I’d try to find one with a good strong Blackburn Mullard GZ34 included, it could save you £100-150 later on!

The thing I don’t like about the Leaks is their electrical protection. There is no plate fuse (unless you count Harold’s green resistor), so if a valve fails catastrophically in a certain way things can apparently go very wrong pretty fast. If I was using mine as a daily driver rather than a second system amp I’d likely try adding one. Any competently designed modern valve amp should have one. By saying that these Leaks are survivors, there are loads of them still knocking around in serviceable condition after a lifetime on this planet so failures so severe they take out the transformer out are thankfully very rare. I’d still not leave mine running unattended though as I'd want to unplug it at the first hint of trouble (a valve red-plating, arcing etc). Valve amps are obviously rather safer in modern use than tucked away in a hot cabinet the way they were originally used, which again helps. I like to think I’d spot any issue fast as it is sitting right in front of me in open view.

PS I’ll be interested to see what folk think the competition actually is!
 
F.Y.I. Hi-Fi Choice magazine featured the Leak Stereo 20 as a 'wild-card' in a group test of modern valve amplifiers in an article circa 1995. It acquitted itself well. From memory , I think that the winning amp was a hybrid Copland design. I did keep the relevant issue but unfortunately it has got 'lost' in a house move and is not readily to hand.

As I have commented before, although the Leak Stereo 20 is perhaps the best-known of the vintage EL84 amplifiers in the marketplace there were numerous other high-quality models of similar output and performance produced in the late 1950s and early 1960s from Armstriong, Dynatron, Heathkit etc. The original Radford STA12 IMHO is a hidden gem within your price range. I've owned mine for 30 years and wouldn't dream of parting with it.
 
Thanks for the quick responses and some great suggestions. Unfortunately, I am not up to building a kit myself or refurbishing a for parts only job, so would have to leave that part to the professionals and factor that into the costs.

Maybe the real question is do vintage valve amps provide better sound than modern valve amps? Does anyone have experience of direct comparisons through auditioning both, if so what did they choose and why? Realise it may be a self-fulfilling prophecy given the title of this forum!
 
Maybe the real question is do vintage valve amps provide better sound than modern valve amps? Does anyone have experience of direct comparisons through auditioning both, if so what did they choose and why? Realise it may be a self-fulfilling prophecy given the title of this forum!

To answer that you really need to define your price point. Valve amplifiers are not cheap at all to make regardless of what some bargain-bucket Chinese stuff may imply. Transformers are the heart of a valve amp and are very expensive to build well. They are also to some degree a lost art. The advantage vintage Leaks, Radfords, Quads etc have is they have *very* good transformers by modern standards. They also tend to have the full three taps (4, 8 & 16 Ohm) so can match to a wider range of speakers than many modern Chinese amps.

To give some perspective a new Radford Revival is around £2800, and to my mind looks amazing value for a new hand-made UK amp with such high quality transformers and build. The Leak Stereo 20 has recently been copied/reissued by English Acoustics and that comes in at £5k. Leben I think start at about £3.5k these days. I think Trons are all SETs, so a different thing, but I suspect you are in a similar price range here. A McIntosh 275, which admittedly is *way* more powerful than any of the other amps listed is around £7.5k.

So, what are you looking to compare to what? For me the choice was very obviously vintage as I love bringing these beautiful things back to life. I’m not an electronics engineer, but I have sufficient soldering skills, patience, and a website full of helpful and knowledgeable people so I can still attain a truly professional result, save some money, and learn stuff as I go. My feeling after owning some very expensive amps and hearing countless others is these old valve amps really are serious contenders if carefully and sympathetically restored. They’ll hold their value too.
 
The KEL84 is very good, I built one years back and really enjoyed it. I also had a Stereo 20 for a few years, which had been restored by Classique Sounds and used NOS Mullards. I regret selling it, even though I made quite a lot of money on it, and would have one again in a heartbeat if I had the money. They are easily as good as their reputation suggests. A passive preamp, a Stereo 20, and suitable speakers is very hard to beat.
 
Review of the EL84 WAD here. A lovely amp IMO and a bit of a bargain, but if you don’t want to build it yourself you obviously have to pay someone else too, and I’d have thought that would be a few £hundred minimum. A good few hours in there (I know it would take me days, but I’m obviously real slow compared to a pro).

PS as Sideshow Bob has turned up I’ll point out I’m currently listening to a Derek Bailey CD (Ballads) through the TL12 Plus monos and JR149s and it is crazy good. A really good valve amp and mini-monitors listened to in the nearfield is as good as it gets in many respects IMHO.
 
I built the KT88 one for a customer about 15 years ago... in fact I had to completely disassemble what arrived as the owner had done such a bad job and then start again from scratch, replacing any damaged components.
It was OK but I was not bowled over. I would have said a good St20 was better and a Radford would have thrashed it.
 
Depends on which version of the KT88 amp. The latest is a different circuit entirely to the prior version that was around about 2005, the biggest changes being the input and phase splitter and the fact that the earlier version had valve rectification.
 
Depends on which version of the KT88 amp. The latest is a different circuit entirely to the prior version that was around about 2005, the biggest changes being the input and phase splitter and the fact that the earlier version had valve rectification.

It was so long ago and the thing was so unremarkable that I can't even remember if it had valve rectification TBH but I would assume from the time frame that it was the earlier version. The owner had tried to build the kit but given up half way through... leaving so many errors etc that the only way to be sure was to completely strip it and start again.

To the extent of my recollection of the sound it was adequate in every area but nothing more... a bit bland really.
 
I got the impression, maybe unfairly, that the cheaper EL84 amp was the better model. The preamp and phono stage were very good too, Rob built a three box one ages ago though no doubt pushed the spec a bit further. I liked those a lot, no idea if he’s still got them. Regardless the World Designs kit is very decent IMO, really nice solid cases, good hefty transformers and great instructions. If I wasn’t in the vintage market I’d be very tempted myself. Obviously great candidates for upgrading too.
 
The KEL84 is very good within its power limits but the WD88VA is definitely the big brother of the two. Mine works very well with ESLs, it did make an appearance at Scalford in 2015 if anyone remembers that year.
 
One thing to consider is that if you buy a 'classic' valve amp, you are unlikely to loose money. Things like the Leaks, Radfords, Armstrongs, Heathkits etc. retain / increase their value if you do sell on.
Not sure the modern valve amps will do that. For instance the WD KEL84 can be had for half the new price if you but 2nd hand. It is a very good amp by the way, but like others here prefer the Leak Stereo 20.
Not sure where you are based, maybe you could 'borrow' some alternatives to try?
 
I went a WAD for a demo quite a few years back to listen to the 6550 amp they had at the time. I think the demo was run by Nick who now runs the HifiCollective shop.
I thought the 6550 was quite poor and Nick confessed that they had asked Andy Grove to revisit it because they also had reservations. It was easy beaten by the SS AKSA 100 Nirvana I had at the time. Nick wanted me to listen to the 300B PSE and after protesting that I didn't want a single ended amp on (engineering) principle, I had to agree that is was actually damned good into the largish Snell speakers they were using.

Sorry for OT'ing a bit.
 


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