HELP! Triple Rectifier rumbling issue

I'm getting a rumbling noise, similar to the sound of a distant helicopter. Its only happening in raw and vintage modes in both the red and orange channels, as well as both modes in green channel. I only have 2 of 3 rectifier tubes installed (1 shattered in shipping when I received amp). I noticed my second 5U4G tube went out and wondered if that has anything to do with it. I run the amp in diode mode at all times. I did the tube tap test and all of my pre and power tubes seem ok. Any ideas guys?

Do you have something in your fx-loop?

Eevil said:

Do you have something in your fx-loop?

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No. Only thing plugged in is footswitch.

I had some rumble when using the parallel fx-loop that’s why I asked :shock:

If you have known good preamp tube you could swap the preamp tubes one by one and check if it goes away?

How often does it appear? I get something very similar on almost all my tube amps (Mark V35, Dual Rectifier, Mark IV, OR15) at band volumes, when my cellphone is on top or near the amp head. I believe the amp simply receives some of the phone's signal and amplifies it.

I just resorted to not keeping my phone on my main amp and all is well.