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Capacitors drying out in an old amp

If one is evaluating old amplifiers how does one know if the capacitors are drying out/dried out. Does the drying out process take a long time? Say, 1 or 2 years or is it quick?

Can the ears tell us if it is so?

I tried to check this but could not come up with anything. However most agree that an amp which is over 15 years old most probably needs the capacitors to be changed.

Quad amps have the current dumping system and according to what I have read are sort of self adjusting amps which do not change the sound characteristics over certain period of time. Is this also related to the issue raised above.

Sorry for so many questions but if someone can explain in laymans terms if possible, it would be greatly appreciated.

Thanks
128x128quadophile
herman
2,261 posts
 
The only ones that deteriorate are the electrolytics.

Check out this discussion of aging capacitors. If it were mine I would change them. It is cheap and easy if you can solder.

The current dumping topology is another matter.
hpims
129 posts
 
Depends on the amp and build quality. My McIntosh MC225 is all original and has no problems. It was built in the mid 60s, making it 40 years old.
herman
2,261 posts
 
It has little to do with the build quality. A 40 year old electrolytic capacitor is not behaving the same as a new one. A 40 year old amp may be functioning with no apparent problems, but it is not functioning as well as it was when it was new.
hpims
129 posts
 
Well, my MC240 was recapped due to a slight hum and the sound quality is now perfect....like the MC225.
GO FIGURE!!
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