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Leak TL/12 Plus / Point One Plus

Yes I'd definitely resist any urge to dive in there and start prettifying it up. Sometimes these visual imperfections look far less annoying and assume their proper significance with some time spent away from looking. There's a few things I'd prefer were perfect inside my amp, but I've drawn a line in the sand now and am just enjoying the music. Unfortunately have had 2,3 instances this evening of the music cutting out for a split second, so hoping it's not the Stereo 20 (have just installed my Chord DAC back from repair, with a recently purchased Naim CDX2 as a transport, so hard to tell what's doing it).

Will keep fingers crossed that the issue you had with the TL12+ is resolved now and you can get back to enjoying some tunes.
 
Pardon my ignorance on such matters (I don't know much about valve amps), but I'm surprised that carbon composite resistors are still in vogue! In another lifetime, I worked for a company that repaired and calibrated electronic instrumentation. A lot of it was very old and often, the carbon resistors would be the culprit. They're not very stable at the best of times & their value of resistance can vary enormously over time! We always used to replace them with metal film resistors, but I'm guessing that there might be a couple of reasons why you might retain them:
  1. To keep the amplifier as authentic as possible.
  2. You can't get the values of resistance in other types of resistor.
  3. Carbon composite resistors sound better.
I would struggle to understand the latter tbh, but as I say, I'm no expert on valve amps.
 
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reasons why you might retain them:
  1. To keep the amplifier as authentic as possible.
  2. You can't the values of resistance in other types of resistor.
  3. Carbon composite resistors sound better.

A combination of all three really. Everything you say is correct, but you will find the real vintage valve amp collectors go to huge lengths to retain authenticity wherever possible, and there is a suggestion carbon does sound better, or at least more authentic, in some locations. This is carried over into the vintage guitar market too, obsessive attention to original detail is again highly valued. I’m not quite that much of a purist, so I compromised with modern carbon film, but I couldn’t get a 3m3 value from the supplier I was using. As such I bought both vintage carbon and modern metal film just for that location. As the carbon measured absolutely spot on with my meter I used them, though that was obviously a mistake in hindsight.

I’ve attempted to find a middle-ground somewhere between modern and authentic in the way I’ve rebuilt both these and the Stereo 20. I certainly didn’t want to fill them full of metal film and poly caps as it just kills the desirability/resale value, plus can push things in a bright, lean direction (i.e. very far from my personal taste), but I still wanted a good reliable amp too. Time will tell if I’ve achieved that. The Stereo 20 was quite a journey too, but it has been superb since the rebuild.

I'll be interested to learn if these improve upon the Stereo 20?

I’ll need to go back and forth a few times, to confirm, but my initial impression is the TL12 Plus are more dynamic and punchy, if a bit leaner, the Stereo 20 a bit more lush. They are far more similar than different though, I suspect the main differences I’m hearing are the valve sets (I’ve been running a set of 1964 Mullard EL84s in the Stereo 20, plus there is the difference in the input and phase-splitter valves). Both great amps for sure.
 
@Tony L many thanks for your response, I was beginning to wonder! As I said, back in my servicing days, we couldn't get rid of carbon resistors quick enough, but at least now i understand the reasons!
 
As I said, back in my servicing days, we couldn't get rid of carbon resistors quick enough, but at least now i understand the reasons!

I guess the thing is how they age as much as anything. Even so some are still going strong, e.g. one of my 303s is still on its original carbon resistors and it sounds superb, has no noise even via 95db speakers, all voltages are where they are meant to be (all the caps are replaced/fresh) etc. It is an early one which dates from around 1970. That isn’t a bad life expectancy, certainly longer than I’d expect modern LCD displays, anything with flash memory etc to survive. IIRC there are some very expensive modern Japanese carbon resistors available (I remember reading something on one of the eastern Leak groups, Hong Kong I think, but not much was in English so I don’t know what they were called or where one would buy them). There have to be some available for the guitar amp community too as no way would you stick metal films into a highly collectable original 1950s Fender Tweed or whatever.
 
I guess the thing is how they age as much as anything. Even so some are still going strong, e.g. one of my 303s is still on its original carbon resistors and it sounds superb, has no noise even via 95db speakers, all voltages are where they are meant to be (all the caps are replaced/fresh) etc. It is an early one which dates from around 1970. That isn’t a bad life expectancy, certainly longer than I’d expect modern LCD displays, anything with flash memory etc to survive. IIRC there are some very expensive modern Japanese carbon resistors available (I remember reading something on one of the eastern Leak groups, Hong Kong I think, but not much was in English so I don’t know what they were called or where one would buy them). There have to be some available for the guitar amp community too as no way would you stick metal films into a highly collectable original 1950s Fender Tweed or whatever.

I have a Fender amp from 1963, and another from 1965, and a Thomas/Vox amp from 1966, all full of original carbon comp resistors, and none suffering from any particular noise issues.
 
Cool, what are the Fender amps?! Bet they are lovely.

I’m pretty certain you’ll see new carbon comp resistors in a lot of modern high end valve amps, e.g. Leben, Shindo etc. I think Graham may use some in his Tron kit too. I’m sure the issue I had was down to using ancient NOS stuff of known slightly iffy provenance, I’m not blaming the core technology at all. If I could have bought brand new from a really credible brand I’d have happily done the whole amp with them to keep the restoration as authentic/accurate as possible.

My ideal with this sort of thing would obviously be a time machine and just popping back to 1958 to buy a brand new amp. I obviously fall a very long way short of that goal in restoring stuff, but I’m really not trying to “improve” anything, nor trying to turn a vintage classic into a Ming Da, Prima Luna or whatever (not implying they are bad at all, it just isn’t my target here). I just want a fairly sympathetic restoration that is hopefully reliable and long lasting without having to deep-dive into crazy expensive boutique parts etc. A middle ground.
 
Just gone over my work with fresh eyes, neatened up a couple of slightly ugly joints, and its fine. Better than I thought when doing it. Being really pedantic there are a couple of green wires on the ECC82 base of the amp#1 chassis that have visibly taken a bit of heat, but I guess that is fair enough as they have been reworked multiple times when replacing the valve base pins (I took some wires off rather than risk hitting them with the iron, and more than once too).

Anyway, all back together and I just tried a power-up now and all is fine. No hum, noise or anything. Hopefully they are now actually done! A useful learning curve and no Stereo 20s died in the process!
 
Anyway, all back together and I just tried a power-up now and all is fine. No hum, noise or anything. Hopefully they are now actually done! A useful learning curve and no Stereo 20s died in the process!

Sounds like you've beaten the buzzy bugger then! Huzzah! So are you going to call it a day now with them? I'd quit whilst ahead, sounds like the problem has been solved. Well done for persevering with it!

By the way the resistors in that 303 mentioned above are all carbon film, not carbon comp. I think there were a couple that were comp. only, but they were replaced when I serviced that one as they were both out of spec. I believe they're Iskra carbon films for the majority.
 
Firstly: glad it seems to be sorted. Persistence pays off!

Secondly: Here is a "cure" for perfectionism:
Instead of spending 90% of the time of a job on the last 10% of (example; perfect painting of the wall corners behind the wardrobe), just do a decent job in a reasonable timescale. Then put a date in your diary for 3 months' time, with the intention of reviewing the work on that day AND NOT BEFORE. If it offends you on that day, redo it. If not it's fine.

I have used this technique and I know that I don't even need to put the date in the diary nowadays... I know that if I stop obsessing on the "decent" results by using this thought technique, it just does not bother me at any later date.

Thirdly; I've only heard ST20 and TL12.1s. The 12.1s were superb!
 
Sounds like you've beaten the buzzy bugger then! Huzzah! So are you going to call it a day now with them? I'd quite whilst ahead, sounds like the problem has been solved. Well done for persevering with it!

Yes, I’m done now assuming they stay buzz-free and reliable long term. They are a very good sounding pair of amps and certainly seem to suit the LS3/5As very well. Haven’t tried the 149s or Tannoys yet. Very pleased the transformers seem to be fine.

Secondly: Here is a "cure" for perfectionism:
Instead of spending 90% of the time of a job on the last 10% of (example; perfect painting of the wall corners behind the wardrobe), just do a decent job in a reasonable timescale. Then put a date in your diary for 3 months' time, with the intention of reviewing the work on that day AND NOT BEFORE. If it offends you on that day, redo it. If not it's fine.

That is good advice for sure. I’m pretty sure I’m done now. It actually looked pretty good on closer evaluation today and I neatened up anything that needed it. If something breaks, e.g. a valve base, then I may well replace wiring at that point, but otherwise it is fine.

PS One thing I need to do is to find some solder I like. I recently bought a new roll as the one I’ve had forever (since the ‘80s!) is coming to its end. I don’t like the new stuff anything like as much as it just has way too much flux and creates a heck of a lot of mess to clear up including brown specks in the work that really take some cleaning. Both are 60/40 lead rosin core, the new stuff is thinner though. I’ve spent much more time cleaning than doing on this job! Anyone got a recommendation for a really nice 0.8 to 1mm lead solder? Ideally on a fairly big roll.
 
PS One thing I need to do is to find some solder I like. I recently bought a new roll as the one I’ve had forever (since the ‘80s!) is coming to its end. I don’t like the new stuff anything like as much as it just has way too much flux and creates a heck of a lot of mess to clear up including brown specks in the work that really take some cleaning. Both are 60/40 lead rosin core, the new stuff is thinner though. I’ve spent much more time cleaning than doing on this job! Anyone got a recommendation for a really nice 0.8 to 1mm lead solder? Ideally on a fairly big roll.

I`d suggest this:-

https://uk.farnell.com/multicore-lo...500g/solder-wire-60-40-180deg-c-1mm/dp/453596

With the proviso that I don`t use 1.0mm solder, I have .46mm, .56mm, .7mm and 1.2mm and also haven`t had to buy new supplies for several years.

I have also heard that Farnell and RS no longer supply leaded solder to non trade customers but it seems hard to pin that down.

I can help with that if you have a problem.
 
Many thanks, I’ll have a look at that.

PS Just grabbed some of the RS Pro in 1mm. No issue with supplying, though my account may be trade, I can’t remember. I don’t have a Farnell account.
 
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Back to the TL12 Plus. I notice they both have threaded screw holes either side of the chassis which kind of suggest there was an optional ‘tube cage’. Anyone ever seen one? I can’t recall ever seeing a non-BBC Leak (TL12.1, not Plus) with a cage!
 
I saw a bronze Leak TL50+ wearing a cage at an auction house after the auction, the auction assistant told me it had sold for £30, that was way back in 1991.

It had a GEC sticker label attached to the cage.

I have one caged out of three of my Leak TL12.1s

So glad to hear that your wayward TL12+ is now behaving itself. :)
 
Cool, what are the Fender amps?! Bet they are lovely.

A '63 blackface Deluxe-Amp (no reverb) and a '65 Champ-Amp. The Vox is a Cambridge Reverb from 1966, one of the odd amps made by Thomas Organ in California. It looks like they started with a Fender Princeton Reverb and changed just enough to Vox-ify it - cathode-bias EL84 outputs, a long-tail-pair splitter, and a tone stack with different turnover frequencies than Fender. But it was my first amp when I was 13 years old. Tom Jennings signed a deal with Thomas Organ to distribute Vox products in the USA, and didn't read the contract. They stabbed him in the back and started making amps and organs themselves instead of importing them from England, allowed to do so by fine print in the signed contract.

The Leak amps appear similar to the Mullard 5-10, which came first?
 
I`ve never seen a TL12+ with a cage and I`ve seen quite a few, Leevers Rich used to supply them with Film Recorders if the customer wanted more power than a single ended EL85 amp would supply (2 watts) then later they produced a simpler in house version.
 


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