Old SS amps

@ronmen 

The idea of the variac is to let dried-out caps reform progressively and spare them the full blast of inrush current while in a compromised state. So going back on the variac at this point is unlikely to make a difference.

Re question 2... a lot happens to electronics in 20 years, both actively used and stored. So... it depends.

That said, I think the compulsive hand-wringing over capacitors (while glossing over everything else) that seems to afflict many in the audiophile community is misguided. A number of potential issues with vintage gear are more important than caps.

@devinplombier

Does that mean you do not have an opinion on the specific question?  Also, what would you consider the more important issues?  'Just to be clear, I'm not trying to be antagonistic.  Please don't interpret my questions that way.  I'm just trying to learn. Thanks.

All well over 20 years, the newest is a Bryston 6BSST. I also still use a Bryston 4BST, 7BST and 10B Sub crossover.

Years ago my dad gave me his MC2125 and C28. I had them serviced and find them fun to listen to but lack the clarity of more modern amps. That said I’d rather listen to this pair over many sub $2500(I think equal value after you pull out the nostalgia value) pre/amps/integrateds, but not compared to many better amps I’ve had.

There is something about this pairing that brings me back 30 years, whether tone or timing or whatever, so there is that piece of the puzzle that’s fun too. 

@ronmen 

No worries, these are good questions.

I don’t have a strong opinion as to whether an amp used daily for 30 years is more likely to need a recap than one that has sat unused for 20 years because caps will deteriorate in both cases, albeit for different reasons. Personally, I would pick the unused one if it hasn’t been plugged in / turned on yet.

Bias drift is quite common and can raise internal components’ operating temperature to dangerous levels (dangerous for the amp that is) if left uncorrected, causing an amp to slowly cook itself to death in some cases. Cooked PCBs are not salvageable past a certain point of doneness, making the amp essentially unrepairable. Such total loss may be uncommon, but it is still best practice to check bias current and DC offset, and adjust them as needed, every couple of years.

Driver and output transistor failure can have significant negative consequences. Same for power supply failure, depending on an amp’s topology.

Granted, modern amps are equipped with protection circuits that are designed to save speakers from being destroyed by excessive DC offset. But early SS amps raw-dogged it; Phase Linear - known for building 300+ wpc amps in the early 1970s out of automotive electronic-ignition transistors, as well as for being the first known audio-related manifestation of Bob Carver - was affectionately nicknamed Flame Linear 🤣

Regular preventative maintenance is desirable with early SS amps.