Bad Phase Inverter

[Dave B]

What are the symptons of a phase inverter going bad? If it does go bad, does it go gradually, or does it go pretty much immediately? I just replaced a microphonic preamp tube and was curious what I should be on the lookout for, because if the preamp tubes go bad, then I guess the PI will eventually, too.

[Blue Strat]

Originally posted by Dave B
What are the symptons of a phase inverter going bad? If it does go bad, does it go gradually, or does it go pretty much immediately? I just replaced a microphonic preamp tube and was curious what I should be on the lookout for, because if the preamp tubes go bad, then I guess the PI will eventually, too.

There's no simple answer to this question. It could go gradually or suddenly. It only takes a second (or less) for almost anything to stop working.

Symptoms could be loss of power, high distortion, no sound, etc.

[Roccaforte Amps]

Originally posted by Dave B
What are the symptons of a phase inverter going bad? If it does go bad, does it go gradually, or does it go pretty much immediately? I just replaced a microphonic preamp tube and was curious what I should be on the lookout for, because if the preamp tubes go bad, then I guess the PI will eventually, too.





A bad PI tube in most cases will reduce output.
What usually happends is one side of the tube
goes bad increasing even order harmonics,
so the amp becomes cleaner sounding.

[Dave B]

Thank you both for the info. Good stuff to know.

[Wakarusa]

Also, just like any other tube going south, they can start to pop and spit and/or do the "frying bacon" thing.