Loud Buzz in Mono


Tube line stage has mono switch. When switching on mono there is an ungodly hum happening. This is only evident when listening to vinyl through phono preamp. When switched over and listening to cd the mono switch works just fine no hum. Any advice would be great.
fromunda

Showing 1 response by fromunda

I replaced a 12ax7 tube in the phono amp with a 12at7 and the hum in mono went away. The 12ax7 was tested as good so what happened here? Any ideas?