Tube Amp Archive

I am trying to understand if there is a correlation between a power tubes idle current, 6V6 specifically, and its breakup point.

Does a lower idle current mean a faster breakup, or does a higher idle current mean a faster breakup?

Or do I not understand and should just watch the pretty glow...?

Ian,

Thanks for the info - very useful. I am changing out tubes in an Ampeg GVT15 (new production, around 2011) - not sure if the bias resistor and cap are common - anyone know?

I normally buy tubes from bob at eurotubes, tend to trust his judgement. But I am wanting to do something quickly this time (rather than wait 3 days for the mail) and the locals don't have matched 6V6s, just singles....hence the basis for my question...

Ok, so maybe I am just missing something. Biasing is more about running the tubes efficiently, than matching the paired tubes themselves...?

Does it make a tonal difference (I am thinking it would) when using matched power tubes on a cathode biased amp, versus using un-matched random tubes. The specific amp in question is an Ampeg GVT15. I am looking at swapping out stock tubes and wondering if matched or unmatched is tonally more desira...