Rose Morris AC30 Hum

[rf7]

I've got similar issues to this amp: AC30 strange problems.

The source of the hum is also the V12B stage in this amp. Grounding the grid does not improve the hum. Pulling the tube eliminates most of the hum. When the amp came in, the reverb section was all grounded to eliminate the hum, and tubes V11 and V12 were pulled.

I tried elevating the heater voltages with 45Vdc and got no improvement. I also tried a 6Vdc heater on V12 and also got no improvement.

Any further ideas?

[jfutral]

I've got similar issues to this amp: AC30 strange problems.

Sorry, I have no further ideas, but thanks for remounting that thread. What a great discussion, it's gold. I never browse that forum.

Good luck all the same.

Joe

[rf7]

More fuel for the fire: Vox AC30 Reverb Model Possible Choke Problem

Moving the wire that he mentioned did not help the hum in this amp. I replaced that wire awhile ago to no avail.

I've got the V12B stage completely isolated from any inputs and from the next stage and I see the same level of hum on the anode that I see on it in circuit. I'm wondering if the location of that tube socket is causing some sort of hum pickup?