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Tube matching: 30 hours vs 0

This should be a pretty simple question. If I knew anyone to call for the answer I would.

I have a Cary amp that takes 4 power tubes. Recently, one blew out so I replaced that one and the one next to it with a matched pair. I've determined that it would be better to replace all 4, so I've ordered another pair that matches the first new pair.

While i wait for the second pair to arrive, i've got the first new pair and the old pair in the amp. I would like to play the amp and listen to music, but am wondering/concerned if putting some hours on the new tubes will degrade them enough so that they will not be matched to the second pair when they arrive.

I estimate I will put around 30 hours total on the first new pair before the second pair arrives. Is this significant? or can i safely fire it up and listen to some tunes while i wait? Thanks all..
tholt
mlsstl
1,440 posts
 
30 hours is only 1% to 2% of the expected useful life of a typical output power tube.

Tube parameters usually are very stable through the life of a tube, which is where the cathode emissions are greater than about 70% of the original value.

Given the other variables in manufacture it is reasonably likely that one of the newer tubes could fail before the one that'd been burned in for the 30 hours.

I wouldn't worry about it.
blindjim
3,092 posts
 
well... there you go!
tholt OP
551 posts
 
Jim, I think that's the shortest response I've ever read from you! Yeah, thanks for the responses guys. Figured it would be ok. Cheers..
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