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Levinson 20.5 monos - Time for a Refurb?

I bought my Mark Levinson 20.5 pure class A mono blocks new in 1990. I loved them for their sound and still do. They have been 100% reliable and I have never had them back to the Levinson or my dealer for anything.

However, they are 16 years old now and except for my Magnum Dynalab tuner, they are the only thing I have not replaced in my system.

Being pure class A amps they run pretty hot.

Question is, is it time I should consider having them checked out, refurbished, capacitors and the like replaced, etc?

If so, who should I consider for this work? Levinson? They are not what they used to be when they designed and made these amps, and I'm not sure they are up to the same quality work they did back then or whether I should trust that their parts will be as good as the original. Someone else? But who?

Has anyone been through this or does anyone have any thoughts about this they can share with me?
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unsound
7,329 posts
 
Herman, I don't have any strong conviction on an absolute length of a caps reasonable use. I am led to believe that caps can be reasonably expected to be reasonably servicable for 20 years. What do you believe the life expectancy of a cap to be? When is a caps qualitive use expired? How often should amps like the Levinsons require maintance? I suspect that the quality and value of the caps used in circa 1990 Mark Levinson products were appropriate for its intended use. Now, if HK believes that their products need service every 10 years, who am I to argue. Then again, I might be a little less cynical if that suggestion came from the original designers/manufacturers rather than a new holding company.
herman
2,256 posts
 
What do you believe the life expectancy of a cap to be?

That's the $64,000 question. I don't have a strong conviction either because it is impossible to put a number on it for any given capacitor. Naim recommends 10 years. Cynics say that is just to generate revenue, Naim devotees say it is essential for maximum performance.

I would agree that in many applications they can be "reasonably serviceable" for 20 years, but most audiophiles are not going to settle for anything reasonable.

If I intended to keep my $35,000 amps and they had 16 year old electrolytics I would have them replaced
unsound
7,329 posts
 
"Most audiophiles are not going to settle for anything reasonable". LOL! Makes one question how "reasonable" audiophiles are?
rwwear
2,867 posts
 
Isn't it true that electrolytics wear out more quickly from not be used than being used everyday?
herman
2,256 posts
 
They don't wear out but can lose capacitance sitting idle. However, once you start to use them again the capacitance builds back up.

A cap that has been sitting with no charge for too long can short out if you apply full voltage all at once. This is especially true for old caps in tube amps because they have a relatively high voltage across them. This is why you see the recommendation to form these capacitors by slowly bringing up the voltage across them when turned on for the first time after a long period of being off.
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