300b tubes burn in time?


I just bought a new pair of Shuguang Black Treasure tubes. For some reason they don't sound as good (open, detailed, life-like) as my old ones of the same brand. 
Do you know how many hours 300b tubes take to fully burn in?

Or I am wondering if I got some sub-par pair of tubes.
essrand

Showing 1 response by essrand

I bought the amps used, so the old ones sounded great all throughout (they must have had a few hundred hours on them at least I figure).

Same brand and model of tubes. Black treasures.

The other tubes should be fine (I think), since the old tubes gave great sound (I didn't replace them, its just one that I mishandled the amp and one of them broke) so am replacing not because the old tubes seem worn out, so I know there is still good sound if I still had the old tubes.

My amps are supposed to be auto-biased.

It's just not sounding that open or lively compared to what I am used to with this amp.