[vishalk]

Originally Posted by Radio Wrangler

You do jump in the deep end, don't you...

iI certainly do David, only way iI get to push myself and learn and iI am determined to do this! Granted it's a big challenge, but for me it will be hugely rewarding.

Just work on one amplifier at a time, it's less confusing that way for everyone.

Agreed

Those three valves with white tops have lost their vacuum and got air inside. the shiny brownish plating inside the tops (and sometimes bottoms) of most valves is a highly reactive metal called the 'Getter' its job is get rid of any residual gas by chemically reacting with it. It's what pumps down the valve to its final vacuum, and it takes care of very slow outgassing or leaks. When the getter is used up, you're left with a deposit of white salts.

My assumption was mechanical damage or coupling caps from the research iI have been doing, learning as iI go along

It's much more likely that these valves were killed by mechanical damage than by electrical damage, but it's not impossible that a failure in the coupling capacitors (Mentioned by Michael above in appropriately bold text) could have those three overdriven to great currents and temperatures which could crack the glass. I too would worry about the transformers.

The amplifiers look mostly untouched, though a few resistors have been replaced by lower noise metal film types ( the standard of fitting isn't up to Leak's standard)

These are particularly good amplifiers of their era. Now, what makes them so good?

The chassis are just painted metal, nothing special. Any other firm could do them.
The valves were off the peg and fairly cheap in their day
The resistors and capacitors were mundane types found in ordinary consumer electronics.

The secret sauce lies in the circuit design. There isn't anything wild, but Leak pioneered using appreciably more feedback than their competitors. Very artful design of the transformers are the heart of these designs. These parts are what allowed Leak to use more feedback and to still keep the things stable.

This is great to hear from you as again iI have been learning all about this

The transformers are the key to the whole thing.

And failing coupling capacitors to the power output valves can kill the transformers. Michael's bold typeface is fully justified.

Confirmed these will definitely be changed

To some people, "refurbish" means to swap every part in the thing.
To some people "Original" means nothing is changed unless NOS parts of original types can be had. Sanity lies somewhere between these extremes.

David this is my dilemma, clearly both the ST20 and TL12 + need refurnishing, yes iI would like to go original like it left the factory, chosen components are key here iI believe.

I like testing, experimenting and discovering as such, the TL12+ will be my testing grounds. Both TL12+ will have different components and from there iI will test how they perform and sound based on the components they have.

Originally Posted by Radio Wrangler

I'm a slow typist and started composing my last post after seeing #4.

Some people swear there are enormous differences in the sounds of different types or even makes of capacitors. Others find this hard to believe and can't find those differences with diligent double-blind testing. The differences simply aren't as huge as suggested, and they may be self-delusion. One side of the argument thinks the other side is deluded, while the other side thinks the first side has defective hearing. It all goes downhill from here...

Well iI know where this is going for me then, iI do agree with you though hence why iI want to try different components in each TL12+

I like good quality, reliable well-made parts. I won't believe in fairy dust without convincing evidence, and this frees up time so I can get on with listening to some music!

Any suggestions and tried and tested parts let me know David!

Oh, yes, the Leak preamps were all considered not worth bothering with.

What are you going to listen to?

I listen to classical music, jazz, funk, chart/pop music, traditional hindi/bollywood music, it ranges iI do like Bass though sometimes iI will throw on some rock, hip hop etc.