Recent JMI / VOX AC30 6 TB with idle noise

[nevetslab]

I haven't seen this version of the Vox AC30/6TB amp. All the AC30/6TB's we have at CenterStaging are the PCB version, which also had the 5AR4's miswired, taking the output voltage to the amp from Pin 2 instead of Pin 8 on the 5AR4 rectifier tube. it's not a hum problem, but is a rectifier tube reliability problem. Take a look to verify the amps' supply is being fed from Pin 8 (cathode of 5AR4).

And, I agree with what Mic said on post #10

I have had two AC30/6TB's that the only hum solution was using a separate filament transformer, disconnecting the heater wiring from the main PT. A little extreme, but that cured it on those two.

[GibbyLover]

I'll try to check the supply of the rectifier, if I figure out how )

It's actually a copy of the early 60s AC30 with added topboost at the back.
I'm wondering if it is normal that the cable that links the 2 top boost inputs makes noise if I pop them and only if the input most to the back is used.