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Pops 300B tubes on turn on in my Vac

Put a set of carbon plate Sophia's in my Vac70/70 amp.Over the last week on start up a couple of the tubes have sparked on the top of the tube resulting in a "pop"sound.
Is this something i should be concerned about it doesn't happen all the time.The set is brand new.
I don't remember that happening before with my amp.
wavetrader

Showing 1 response by audiofeil

audiofeil
4,011 posts
 
Did you set the bias "low" before installing the new tubes?

When circuits are not self-biasing I always adjust the bias to a much lower setting and then increase as needed when changing tubes.

Good luck.
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