First pre-amp tube failing in Runt 50

Anyone else have this happen? Three tubes in a year have failed. Gigging the amp 2-3 times a month.

It’s shitty tubes, not the amp.

Take some voltage measurements on the tube pins and report back? Pins 4,5, and 9, meter set to AC voltage. Then pin 1 and pin 6 meter set to DC voltage. Ground your black meter probe. You can also place your ground on pin 9 and read from there to your hot probe on pin 4 or 5. Doesn't matter as they are jumpered anyway. When you read pin 1 and 6 ground your black probe to chassis. You know how to do this Mel. Bases on the measurements we can tell you if it's the amp or like Paul says shitty tubes. More probable it's shit tubes. It could be a plate resistance causing to much voltage through, but doubtful.

Thanks for the replies. I’ll try taking the suggested readings and report back.

Jj preamp tubes die. Nothing strange with the amp..