I have just finished restoring an old 1962 Ampeg Reverberocket. This is one is version R-12-RA with 5Y3 rectifier and 7591 power tubes. I bought knowing it had a fried power transformer which I managed to get re wound by a local company (Transformer Equipment LTD in Kent, great people)
I have replaced the tubes and all electrolytic capacitors, the amp is working nicely and voltages seem to be in the ballpark, but I am experiencing too much hum. The hum disappears if the preamp tubes are removed, but is present with the phase inverter in the circuit. I have tried three different ones so I would exclude a defective tube
I am thinking more of a grounding problem. The amp had been serviced before, so I am not entirely sure what the original ground arrangement was. From what I have found V1 power supply filter capacitor and cathode resistors were grounded at the input jack sleeve, while the rest of the circuit went to chassis at the filter can capacitor, and some of the potentiometers were grounded to their own shells
I have tried grounding the filter capacitor section at the input jack sleeve, but that made no improvement
I have read that these Ampegs aren't the quietest amps, but I would really like to improve the situation
Would you recommend to modify the grounding arrangement or rather look into something else ?
I have replaced the tubes and all electrolytic capacitors, the amp is working nicely and voltages seem to be in the ballpark, but I am experiencing too much hum. The hum disappears if the preamp tubes are removed, but is present with the phase inverter in the circuit. I have tried three different ones so I would exclude a defective tube
I am thinking more of a grounding problem. The amp had been serviced before, so I am not entirely sure what the original ground arrangement was. From what I have found V1 power supply filter capacitor and cathode resistors were grounded at the input jack sleeve, while the rest of the circuit went to chassis at the filter can capacitor, and some of the potentiometers were grounded to their own shells
I have tried grounding the filter capacitor section at the input jack sleeve, but that made no improvement
I have read that these Ampegs aren't the quietest amps, but I would really like to improve the situation
Would you recommend to modify the grounding arrangement or rather look into something else ?