Your phono section may have AC tube heaters instead of the (preferred) DC. Some 12AX7's don't like AC and will let you know by humming.
changing tubes in my phono causes hum ?
i have a tube phono that uses "2"-12ax7's one for each channel. with the mullards i get "0" hum. when i change them out to any other tube like sovtek "low noise" , or electro harmonix i get hum. i like to tube roll and dont understand esp with the low noise tubes. suggestions would be appreciated.
thx,tim
thx,tim