I have Linn Klout Power Amp which I bought second hand around 10 years ago. Amp itself is probably 12-14 years old. At the moment it's working perfect however I'm worried that due to the age of Amp the Electrolytic Capacitors might start to leak and degrade.
So my question is basically is: What is the lifespan of these type of Capacitors?
The hour rating of electrolytic capacitors assumes that the cap is being operated in a worst-case scenario.
This means that it’s always being operated at the specified temperature and maximum ripple. Those conditions are not typical.
For example, many caps are rated at 85° C, which is 185° F here in the US. The caps in your amp are probably not being subjected to anything close to that. Some caps are rated at 105° C (221° F) or even a bit higher. That would probably burn your finger if you touched it.
A old post on another forum quotes Panasonic’s website which says “
In general, the capacitor life is approximately doubled when the temperature decreases by 10° C.” The post gives the following example: “
A cap that’s rated for 3000 hours at 105° C would be rated for about 144,000 hours when operating at 45° C (113° F).” It’s entirely possible that the caps in your amp are even cooler than that under normal conditions.
I’ve restored a lot of vintage tube gear which is mostly from the 1960s.
I used to always install new electrolytic caps until I got a cap checker and an ESR meter. I'll typically bring the voltage on a piece up very gradually with a variac - sometimes over a period of 18 hours and then, the next day, start over and do it again. This is because I don't always know when the unit was last powered up. Then I use a cap checker to check to see if the value is in spec and to check for electrical leakage at the full rated voltage of the cap, again for several hours. Rated voltage is always higher than actual operating voltage in the amp and often significantly higher. The only time I've ever seen a cap that is physically leaking is when a previous "tech" has installed a cap whose voltage rating is too low.
Then I check ESR. For years I used a cheap ESR meter and I was never sure if its readings were really accurate. So, instead of relying on the readings themselves, I always compared them to a new cap - usually whatever cap I would use as a replacement. If there was no significant difference, I figured the old cap was still usable. Surprisingly, I've actually come across some old caps whose ESR readings were better than a new cap.
The only vintage caps I just automatically replace now are original cathode bypass caps. When I used to test them I found that they were almost always out of spec. So now I just replace them without bothering to test them.
Note that these are all amps I own. And my experience is only with tube amps. But from what I’ve seen when caps degrade it’s a slow process which eventually results in hum. Perhaps I’ve just been lucky, but I’ve never had a cap suddenly or catastrophically fail. I have only had a couple of 60 year old amps and radios that had power supply hum after being powered up slowly.
You should certainly approach this in whatever way makes you most comfortable. But IMO hauling an amp to another country for service seems a bit extreme - especially if it’s operating normally.
If you’re capable of working on the amp you might want to find a cap checker that can test at full rated voltages and an ESR meter and test them yourself. But I suspect that you’ll notice an audible difference if any of them start going bad.
All my tube amps are wired point to point so I don’t have any issues with matching caps to a circuit board. If you can’t find modern caps that fit you might be able to mount them on a separate piece of perfboard if there’s enough room inside your amp. Then wire them to the existing board.
