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Leak Stereo 20

Alex S said:
Can owners confirm that the Leak is indeed pretty easy on the valves. This thing will do 3000+ hours a year and I’ve just found out what a full set of NOS Mullards costs!
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It’s easy on the ECC83s and GZ34, they last very well. I’d save a set of Mullard EL84s for serious listening. FWIW I’d not use a vintage valve amp for background listening at all. Mine just gets used a couple of hours a week in its dedicated system for the lights out nearfield stuff. A 303 does all the day to day stuff.
 
I have considered bringing the SS amp back into service for background/normal but it would mean another set of speaker cables and the risk of a family member turning on the S20 with no speakers connected.

I do have a headphone setup on my desk and it wouldn’t take much to rig up the ProAcs there. I don’t like headphones much. I work in the same room as my system and find it difficult to resist.

I could also use much cheaper valves day to day and reserve the Mullards for special occasions.
 
I'd be inclined to just grab a matched NOS quad set of Russian el84 equivalents and see how you get on.

I found it was the ecc83s that had the most influence on the sound.
 
EL84s, that’s what’s in it now I think, with a Harma GZ34 and Golden Dragon ECC83s, so it’s those that are probably the ones to change. Of course they are also the most expensive NOS Mullard-wise. (My phono also needs one, or an 803S and they seem to cost a grand!).

Thanks for the Sovtek LPS heads up chiily. (Finally I’ve stopped calling you chilly).

Okay, a good trawl puts the Sovtek route almost exactly half the cost of the Mullard route FWIW.
 
Yes, that one (input) is the most critical sonically in the whole amp. Put your very best ECC83 there, and it needs to be a quiet one.
 
Great. I'll try everything and if I can get away with the Mullard at input only, I will - or would it be odd if I mix ECC83 brands? Guess I'll find that out soon...
 
Mullard ECC83s and GZ34s last exceptionally well and even at todays crazy prices are likely no dearer than Russian valves that you’ll likely replace multiple times in the same timeframe. Many vintage Leak amps still have their original valves which test fine. I have two Mullard ECC83s and a GZ34 that came with my Stereo 20 and the 83s still test good and the 34 works (my tester can’t test rectifiers). The one of my TL12 Plus that had original valves had two good EL84s and a ECC81. The EF86 was fine too, though again my tester can’t test that. Annoyingly the GZ34 had taken a knock and leaked, a real shame as it was a metal-base one that would have been worth a few £hundred!

This said I still just wouldn’t recommend a vintage valve amp for casual background listening. Leaks are truly fabulous amps, but when they go wrong they can go wrong pretty fast, e.g. a EL84 failure of a certain type can even take the output transformer out if you don’t spot it and react fast. Their electrical protection is crude. The only protection is a 2 Amp fuse at the back. A lot of damage can be done to the amp before that blows. They also run fairly hot, so no way would I want to be running mine all day in a summer heat-wave. They were famed for leaking transformer wax in hotter export countries such as Australia and South Africa, though admittedly people did tend to partner them with the Leak preamp which draws power from the S20 transformer and then keep everything in a poorly ventilated cabinet. I’d definitely get a 303, T-Amp or something like that for work/background listening. The Leak is something special, not a daily runner. Think of it as an E Type or whatever, you don’t use it all year round for getting the shopping from Asda etc.
 
All fair points. A couple of observations. It's been playing music solidly since 9.00am. I can rest my hand on the mains transformer and will admit it's slightly uncomfortable, the output transformers are warm but I could leave my hand there all day, ambient temp is 25. Car analogy not so good for me, S2000 (not an E Type but a 'whatever' I admit) is my daily driver and goes to Aldi constantly. I can turn it off within 5 seconds (the Leak) - possibly not quick enough. If it blows up it can at least be fixed. I might get run over by a bus tomorrow.

Unfortunately, Tony, I don't have multiple superb systems just this one and a decent one in a bedroom. (And a couple of decent ones lent or in a cupboard).
 
I can’t think where to sensibly put the ProAcs or the AN AX2s. I have a ghastly feeling Tony has made me dig some Audioengine A2s out of a cupboard for casual/work listening.

Okay, the Audioengines aren't brilliant but they're actually quite good, imaging fabulous, in this reverse mullet system: MacBook Pro/Audirvana, Chord 2Qute, Sugden Headmaster, Audioengine A2. It's all I have. Sorry, further discussion will be about the Leak S20.
 
A Flock of Mullards has arrived. I"ll stick the GZ34 and an ECC83 on the input for starters.

IMG-3877.jpg
 
Where did you get the GZ34 from Alex? I'm after a couple, at a reasonable price mind you :)
 
From a PFMer. I paid the going rate for his very best one. He had another for sale, cheaper, for £70 from memory.
 
I have spent the day progressively adding Mullards, to the point where the Leak is now fully loaded. These are sighted tests obviously but my expectations in advance were not quite what transpired.

I started with GZ34 and one ECC83 on the input. Obviously better by all aural measures but not significantly. Took the dogs for a walk and then added the two remaining ECC83s. This was a pretty huge lift that I didn't really expect. I know Golden Dragons as a brand since I formerly had to buy 8 x EL34s and certainly wasn't going to do that with Mullards so the Dragons were the best cost/performance valve I found. Er, not here, they are absolutely obliterated by the Mullards.

A break to do some work to pay for these goddam things and in went the EL84s. I didn't know what to expect here since it's fitted with Sovteks that are well regarded and Jez has repeatedly advised the Mullards are 'pipe n' slippers' - hash pipe and Alladin slippers maybe. They are sublime. I know what he means, they are a touch more laid back but they are so musical it's a joy. To speak hi-fi, they are better defined in the bass, imaging, soundstage just better and better defined and, most of all, they just flow beautifully.

So, a lot of money but worth every penny for me. I am attempting to ration myself with little success so far.

I would like to thank the PFMer who reached out to my WTD. He knew what he was selling and doing. Each valve measured, with the results in the box, properly packed and promptly sent. I paid a fair price - PFM classifieds are not the place for bargain hunting gamblers when it comes to stuff like this. I knew that. Thanks David.
 
When a Leak 20 is on song, it's a struggle to beat in the right set up. Lovely tale. Enjoy.

When it's cooled down anyway !
 
FWIW I have tried a lot of very rare and expensive valves in my Stereo 20 and not found anything I’d take over a genuinely good set of Mullards. I do really like the Russian military 6P14P-ER or EV though so whilst I have a very strong (possibly NOS) set of 1964 yellow print Mullards I tend to run the Russian ones to save the Mullards. The Russian ones are more forward, the Mullards create a bigger deeper soundstage. Both good.

Also worth baring in mind that there are five or six completely different Mullard ECC83s and getting on for that with GZ34s. A few variations of EL84s too. The thing to look at is the etched code. This gives the valve type e.g. ECC83 MC1, F91 (both long-plates), I61, I63 plus whatever the Mitchum box-plate was called (I’ve got one, its in my guitar amp!) etc. They all sound very, very different from highly dynamic and a touch forward to the stereotypical warm sound people who’ve only heard ‘70s Mullards cite as the character. Many variables. There are changes within type, e.g. an early I63 with copper rods sounds different/better to a much later ones with nickel. One can get quite obsessive about such things. I seem to have been very lucky, Mullards seem to find their way to me to the extent I’ve likely got 15-20 or so nice ECC83s of differing eras, mostly from random auction lots or in other equipment. Same with GZ34s, I have enough not to worry now.

PS Regarding the EIs Jez mentioned: the silver-plates are a very nice sounding valve (grey plates far less so, but still decent). The problem is reliability, every single one I’ve owned, and its been a fair few, went noisy or microphonic after not too long. You’ll end up spending far more cash on those than a ‘60s Mullard which will almost certainly outlive ten of them!
 
Thanks Tony. I’m a bit of a novice so no idea what I bought - perhaps you can tell from the image. I will do further research since they’ll need replacing at some point but right now I’m extremely happy.
 
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Everything bar one ECC83 with the different ‘shield’ logo will be ‘70s. If you look closely at the glass you will find an etched code somewhere, something like:

I63
B814

The first line is the valve type/construction, the first letter of the second line is the factory, in this case B=Blackburn, the rest is the date code, the first number being the year, so 1968 or 78, other clues tell you which e.g. the logo, the valve type number etc. The other two numbers are I think week of year. Prior to a certain date the code was only three digits. Loads of good info here including the linked files.

PS Mullard made a lot of valves which were re-branded, so you can find these codes on valves with different labels. They tell you the things you really need to know: type, factory, date.
 
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