2. amps-preamps
  3. 1374456013

OK to replace one power tube for amp?

I have Joule Stargate Monos that use the Russian 6C33C-B power tube, two per amp. One of them isn't holding bias very well... wandering a bit. Can I just replace the one tube? Each power tube is individually biased in this amp and I've heard that matching pairs with 6C33s is just not something that happens so it would seem ok to buy 1 but I didn't know if having tubes of different ages was bad.
dhcod
rrog
1,958 posts
 
Most manufacturers estimate tube life in their equipment.
brf
1,715 posts
 
Tubes age just like people. As they get older, they slow down and are less dynamic; they don’t have the same sparkle and don’t have the same frequency extremes. They are just like an aging athlete; they can still play the game, put not at the same level.

The best way to determine if you need new tubes is to buy new tubes and compare for yourself. If there is no sound difference, put the new tubes away until that day comes.
rrog
1,958 posts
 
Brf, Speak for yourself :)

Good advice on buying new tubes and compare. This is my phylosophy except I leave the new tubes in and keep the old tubes as spares.
mechans
3,048 posts
 
I will argue that you should replace both tubes. The ability to hold bias is only one aspect of tube engineering. The tubes' tone also changes with age and this ought to be considered. I would and have replaced whole quads of EL-34s for thid reason in part. So take the sound quality into consideration a tube is not just a power maker.
More to discover