Hi everyone.
I have been into valve equipment for many years, mainly radios.
Recently I bought a job lot of stuff, which turned out to be mainly audio stuff.
This included a pair of Quad ESL57 speakers - WOW what a revelation they were.
This has got me interested, and so I now need to sort out and keep a valve amp to go with them, the choices are:-
Leak stereo 20
Radford STA15 mk III
Radford STA25 mk III
Pair of Leak TL50+
Any opinions on which one will best go with the 57s, which one is best etc??
With thanks
Richard
I have been into valve equipment for many years, mainly radios.
Recently I bought a job lot of stuff, which turned out to be mainly audio stuff.
This included a pair of Quad ESL57 speakers - WOW what a revelation they were.
This has got me interested, and so I now need to sort out and keep a valve amp to go with them, the choices are:-
Leak stereo 20
Radford STA15 mk III
Radford STA25 mk III
Pair of Leak TL50+
Any opinions on which one will best go with the 57s, which one is best etc??
With thanks
Richard
Leak stereo 20
Radford STA15 mk III
Radford STA25 mk III
Pair of Leak TL50+
I've had quite a few Leak amps and modified a lot of them, and I would say with confidence that the stock Leaks, with the exception of the TL10 and earlier ones, can be easily outperformed by most valve amps. The TL50 in stock form is not very interesting sounding either. So as far as Leaks go, I'd say modify them or leave them. Now, since the Stereo 20 is not so collectible as the others, it's a good candidate for modification. I could give you some instant tips on this if I can dig them out of my files - briefly, a 6N30 DC coupled into a 6N1P phase splitter is a huge improvement, and you could also rewire the output transformers as suggested on this site in previous threads. A modified Leak can sound quite good. Now we come to the collectibles. The TL50s and the Radfords should be left original. Good news - they're worth money, bad news if you don't update the parts you are losing performance.
So my conclusion is that if you want sound that is at least one level up from these old classics, you either modify the Stereo 20 or use something else entirely. I recently built a PPP 6V6 triode amp (using 7C5, the loctal equivalent) with a 6J5 DC to 6SN7 front end (using 7A4 and 7AF7 which are round plate). This sounds absolutely delightful, and is better than any version of rebuilt Leaks (including radical ones like my all-triode PPP 6S4 one) and no doubt all the Radfords too. It's simple to build, cheap, and will give you another level up of quality (built with good parts). Alternatives are 2a3 and 300b amps. with what the Leaks and Radfords are worth, you could sell one or two if you don't want to do a build, and just buy a good push pull DHT amp.
Classics are wonderful to collect, but not really for serious day to day listening. Andy
Radford STA15 mk III
Radford STA25 mk III
Pair of Leak TL50+
I've had quite a few Leak amps and modified a lot of them, and I would say with confidence that the stock Leaks, with the exception of the TL10 and earlier ones, can be easily outperformed by most valve amps. The TL50 in stock form is not very interesting sounding either. So as far as Leaks go, I'd say modify them or leave them. Now, since the Stereo 20 is not so collectible as the others, it's a good candidate for modification. I could give you some instant tips on this if I can dig them out of my files - briefly, a 6N30 DC coupled into a 6N1P phase splitter is a huge improvement, and you could also rewire the output transformers as suggested on this site in previous threads. A modified Leak can sound quite good. Now we come to the collectibles. The TL50s and the Radfords should be left original. Good news - they're worth money, bad news if you don't update the parts you are losing performance.
So my conclusion is that if you want sound that is at least one level up from these old classics, you either modify the Stereo 20 or use something else entirely. I recently built a PPP 6V6 triode amp (using 7C5, the loctal equivalent) with a 6J5 DC to 6SN7 front end (using 7A4 and 7AF7 which are round plate). This sounds absolutely delightful, and is better than any version of rebuilt Leaks (including radical ones like my all-triode PPP 6S4 one) and no doubt all the Radfords too. It's simple to build, cheap, and will give you another level up of quality (built with good parts). Alternatives are 2a3 and 300b amps. with what the Leaks and Radfords are worth, you could sell one or two if you don't want to do a build, and just buy a good push pull DHT amp.
Classics are wonderful to collect, but not really for serious day to day listening. Andy
Looking through your post again, maybe you are saying you have narrowed down your wish list to the four you mention - I'd assumed you had all four, so I may be in error. In fact I come from Bridgend, but live up in London. Shame I'm not still in Wales - (unless I pay a nostalgic visit) I have a few amps you could demo. Andy
Both the Radfords are superior to either of the Leaks in terms of accuracy and noise level. I have restored (in terms of new parts but no circuit changes) both a pair of Leak TL12+s and a Radford STA25 for a friend who has a pair of large Klipschorn speakers (i.e very sensitive). When you connect the Leaks to them you can hear their noise in all its glory ; when you connect the Radford, there is virtual silence except for a little hiss at the tweeter if you put your head close to it. The Leaks have an inferior power supply with no choke and are much too sensitive. You can change the sensitivity in the TL12+s by wiring the input EF86 as a triode and changing the feedback components but I don't know how to alter the Stereo 20 front end. If I were you I would keep one of the Radfords and flog the rest on eBay. You'll make a lot of money.
Agreed, get rid of the Leaks unless you plan to improve them significantly. Even then, it's doubtful which, if any, of the original Leak parts are worth retaining - in the case of the Stereo 20, probably only the chassis!
I don't know about the Radfords, except that they have a good reputation. However, the circuit uses a peculiar triode-pentode LTP splitter, apparently to minimize its input capacitance (or so I've been told).
I don't know about the Radfords, except that they have a good reputation. However, the circuit uses a peculiar triode-pentode LTP splitter, apparently to minimize its input capacitance (or so I've been told).
Hi
Thanks everyone for the replies.
I have not got any of these amps working yet, I am about 3/4 of the way through the stereo 20.
I tested a few caps, all leaky, and the power supply caps were not up to much, high ESR readings - so all new caps, and quite a few resistors were well up on value so I suspect I will end up changing most of them as well.
Have not got to the valves yet, will have to dig the AVO valve tester out and see what they are up to.
If I get all 4 going I will let you all know what I think.
It sounds like one of the Radfords is the one to keep.
Thanks everyone for the replies.
I have not got any of these amps working yet, I am about 3/4 of the way through the stereo 20.
I tested a few caps, all leaky, and the power supply caps were not up to much, high ESR readings - so all new caps, and quite a few resistors were well up on value so I suspect I will end up changing most of them as well.
Have not got to the valves yet, will have to dig the AVO valve tester out and see what they are up to.
If I get all 4 going I will let you all know what I think.
It sounds like one of the Radfords is the one to keep.
It sounds like one of the Radfords is the one to keep.>
Why not keep them both! They'll go up in value. For Leak stuff, join the Leak forum, hjleak@yahoogroups.com. Plenty of activity and loads of help for restoration from people who've done it. You'll get offers from Leakies if you don't want to put it on ebay. You'll probably get some interest from Hong Kong for the TL50s. I never liked the ones I had, but they are collectible.
The Radfords are worth a really good restoration - remove rust and clean up paintwork, nice parts etc. The 15s are really nice, and 25s good too. Something to keep in the collection. Won't sound as good as a 2a3 amp, but Radfords are real classics to own. Sounds like you have some winter evenings ahead with the soldering iron out!
Why not keep them both! They'll go up in value. For Leak stuff, join the Leak forum, hjleak@yahoogroups.com. Plenty of activity and loads of help for restoration from people who've done it. You'll get offers from Leakies if you don't want to put it on ebay. You'll probably get some interest from Hong Kong for the TL50s. I never liked the ones I had, but they are collectible.
The Radfords are worth a really good restoration - remove rust and clean up paintwork, nice parts etc. The 15s are really nice, and 25s good too. Something to keep in the collection. Won't sound as good as a 2a3 amp, but Radfords are real classics to own. Sounds like you have some winter evenings ahead with the soldering iron out!
When I replaced all the caps (leaky) and resistors (drifted waaay off) on my old stereo 20, it sounded pretty good.
The preamp/control unit is rubbish and should not be used, and the sensitivity is way too high; but with a telefunken 12AX7 in the front end and all Mullards for the rest; my stereo 20 sounded great- no hiss, no hum and it had a decent amount of clean, yet engaging power.
One suggestion- replace the power supply caps- in mine the originals were all very leaky and got warm during use. buy the JJ electrolytic caps, they bolt straight in. install a power switch or bypass the power switch jack.
Its a classic design, if I want something of my own design I will build it! This also goes for your other amps. By the way the radfors will go for silly money on eBay (or to us valve nutters in London)
The preamp/control unit is rubbish and should not be used, and the sensitivity is way too high; but with a telefunken 12AX7 in the front end and all Mullards for the rest; my stereo 20 sounded great- no hiss, no hum and it had a decent amount of clean, yet engaging power.
One suggestion- replace the power supply caps- in mine the originals were all very leaky and got warm during use. buy the JJ electrolytic caps, they bolt straight in. install a power switch or bypass the power switch jack.
Its a classic design, if I want something of my own design I will build it! This also goes for your other amps. By the way the radfors will go for silly money on eBay (or to us valve nutters in London)
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