Express Build - oscillation with certain tubes?

[NYC_Blues]

I have an Express build, and the V1 tube seemed a little microphonic. It is a GE gray plate.

I replaced it with another gray plate and I could hear a helicopter sound with volume on 0. It was less with volume from 10am to about 1pm then came back above that. I moved wires around, took out the bright caps, but still had that pulsing.

Put back the first GE and the helicopter (oscillation?) sound went away.

Could somebody explain this? Different gain of the two tubes?

Very strange. Had me worried, but I guess with certain tubes it's ok.

Taking off the bright caps even though disengaged did seem to take away some of the hiss.

[RockinRocket]

Its good practice to keep a set of know perfectly quiet tubes for testing .
Do you have grid stoppers on V1?

[NYC_Blues]

No grid stoppers

I've read differing opinions here on how Trainwreck-esque they are

I coild try