I have found about 40-50 hours typical are required for break in of tubes. Some brands and types more, some less. It could be that the new tubes you put in are just not a good match for the preamp. I've had a couple of different pieces of gear that took like 8-10 tries to find the right tube. It's a crap shoot for sure on some gear.
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- 8 posts total
- 8 posts total