can old tubes in a bass amp cause tuning issues?

[jessekates]

I have a new bass player in my band. He plays an old 60s or 70s ampeg tube head with 4 6l6s in it (or something similar.) I don't think the tubes have ever been replaced, or if they have, it's been decades.

Some of his notes sound suspiciously out of tune, but it's very intermittent. He's got a gibson thunderbird and the tuning is spot on at the start of the night. And one song will sound terrible when the next will sound perfect (even when he's playing in positions high up the neck.)

He may just be overbending certain notes (sloppy fingering), but how much can old tubes contribute to tuning issues, if at all?

[Clearspider]

Probably needs his bass set up and the intonation adjusted.

[vibroverbus]

He plays an old 60s or 70s ampeg tube head with 4 6l6s in it (or something similar.)

Yes when this starts happening the amp is usually junk. He should just buy a new one. Tell him I'll take this one off his hands for the cost of shipping. ;)

The best amp-related explanation isn't tubes but could be bad power supply filtering causing ghost notes from intermodulation with the PS ripple. (Search this forum for a couple of ghost note threads from the last couple of weeks...) And if indeed this amp hasn't been serviced in decades/ever then the filter caps are very likely to be toast.

Does he have a backup amp that you could rehearse/gig with once to see if the problem is him or the rig?