Leak TL/12 Plus / Point One Plus
Tony L
Administrator
Finally plucked up courage to stick my lovely possibly NOS quad of yellow-print Mullard EL84s into the TL12 Plus. They sound stunning, the missing piece. The Russian 6P-14P-ER I usually use are fabulous valves, stunning value, but just a little bright in the TL12 Plus amps. They suit the Stereo 20 better. The Stereo 20 isn’t really 2xTL12 Plus even though that was the design brief. The input valves (ECC83 vs EF86), phase splitters (ECC83 vs ECC81), and the output transformers are all different, and these amps do certainly sound a little different. The TL12 Plus a little more upfront and forceful. The Mullards really suit them; wide open, plenty of dynamics, bite and speed, but no harshness. I may as well use just them here for a while as my hearing won’t get any better than it is now with increasing age, and they aren’t something I’d ever sell. So a full vintage Mullard set right the way through!
lordsummit
Moderator
Is that in the record shop system Tony? They must be fabulous indeed if they’re beating the Stereo 20.
Tony L
Administrator
It is more a slight character difference than a win/lose thing. Like with so much in hi-fi I couldn’t really tell you which I prefer, though forced to keep one I’d go with the pair of TL12 Plus as they look so good! IIRC they are technically a couple of Watts more powerful too, which is both good and bad as they run the valves a bit harder.
Barrymagrec
pfm Member
That`s a massive change. It may or may not work well but it`s no longer a TL12 Plus.
Tony L
Administrator
The unmodified TL12 Plus, like the Leak Stereo 20, is so high gain it pretty much precludes using an active preamp in a modern system. Fine if like me you are happy with a really high quality stepped attenuator, but far more of an issue if you need more functionality. It means I have two conceptually different systems as in any real sense my (main system) JC Verdier valve preamp can’t be used with the Leaks as the gain staging is so wrong the volume knobs are unusable (even on the Verdier’s lowest setting) and the Leaks find the noise-floor in the Verdier. As such I can certainly see why someone would do this kind of modification, but it is not something I’d do to mine.
Barrymagrec
pfm Member
There are better ways to reduce gain than to replace a high gain pentode with two low gain triodes......
When Leak designed their range of amplifiers back in the 1950s/60s, source devices like tuner, tape and phono had very low outputs, a tuner for example might only output 75mV, therefore Leak designed their amplifiers to have more gain in the power amplifier section and much less gain in their Point One control units. Note: they weren't called preamps back then. These control units were more of a switching device, so to switch inputs, to change EQ's for record playing and to select different EQ's for tape record and replay, rather than an amplifier with gain, although they did provide some gain. As Tony says, it is best to use a passive preamplifier or a Transformer Volume Control (TVC) with the Leak power amplifier range. From about 1982 when digital came on the audio scene, the outputs of line level devices leaped up to about 2 volts, so this required a different approach to the overall gain in the amplifier chain. About 30 years ago I did offer a conversion to reduce the overall gain of the Leak amplifier range so these power amplifiers could be used with modern day preamplifiers, but without effecting their fine sonic performance.
Pretty awful rebuild really. If they can't do that properly then that doesn't say much for their gain modification...
toprepairman
pfm Member
Don't believe those 300R 5W resistors are original.
Tony L
Administrator
Maybe not, the other one had different ones:
Both are 1st version champagne coloured TL12 Plus, so within a couple of years of each other and have the earlier output transformers and circuit which was harder on EL84s.
They are both absolutely identical now and have the later resistor and cap values to give the valves a slightly easier time:
PS I’m obviously just reposting pics from back up the thread, but it saves folk going back pages. Since finding the fault (a broken pin in a valve base) they have both worked flawlessly. I’m even running my original 1960s Mullard EL84s in them, so a full Mullard valve set throughout. They really are fabulous amps.
I know the Leak's I have not authentic enough to be called "original" but given the sound quality is accept to me I shouldn't be too bothered. As long as you change one component that" authenticity" or "originality" would be long gone. This is so easily happened in the valve equipment because we love tube rollings from time to time. This itself may not be seen as drastic as changing the circuit completely. In my case at least I know there are changes within this particular amp. I will accept that. This morning I just received the new EH 7025 valves and I thought this is fun. The narratives are in Hong Kong Cantonese describing that I was looking for some matching sound I like with the Leak and Trilogy and so EH 7015 was bought since there some praises on the net. Most of all I explained that the EH 7025 is only 1/4 the price of some basic Mullard ECC83 tube.