V7 Driver/Phase inverter tube question?

[thalweg]

I've twice in a year had to replace the preamp tube in the V7 position. When faulty, It would cause a severe volume drop (90%) in all channels, all voicings, all power stages (10w to 90w), and in all rectifier or diode settings.

What function does this tube perform? Is it common to have it faulty in such a short period of time? (7 months there about.) I have no overdrive pedals and have moderate gain settings in all channels.

Thanks in advance to helping out.

Cheers

 

[thalweg]

Answered my own question with this...a fantastic phase inverter tube primer that I've found. Easy to digest for the newbie tube amp owner.

http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf

Suggests that the Phase inverter tube is the one of, if not the, hardest working tube in the amp and should be replaced at the same time as a power tube.

 

[MrMarkIII]

Whatever. Your problem is still not normal. Call Mesa.

 

[thunda1216]

a preamp tube can fail at any time. they usually last longer than your experience, but with new production tubes it can happen in a very short period of time. find a good NOS USA tube and try it in that position.

 

[thalweg]

Thanks for the recommendation thunda