>My question is, do the carbon composition resistors used in US
>made amps tend to go high resistance with age?
Last year, I measured some unused 5% carbon comp resistors that were still in
the full military packaging they had been placed in when new in 1964 (complete
with NATO stock number on them). That's each one individually sealed in a
polythene bag inside another sealed polythene bag. They all measured between 25
and 50% high.
Funnily enough, a 1939 50kohm 20% tolerance carbon 'stick' with radial wire ends
and a 'body - tip - spot' colour coding taken from a National HRO came out at
The 'High Stability' carbon comps (distinguished by having a pink band as well
as the suual colour coding) don't appear to drift very much at all.