Feedback in V1 through positioning wiring.

[Mark]

I have heard people talk about altering the position of the wiring of the first stage to provide feedback. I've heard different people refer to it as either positive or negative feedback. So I'm not sure about all this being correct.

I haven't tried anything yet, but I'm not expecting too much. The wires concerned are the plate wires and cathode wires of the first stage.

Having the cathode wire of valve V1a very close to the plate wire of V1b could provide a small amount of capacitance between these two stages.

I think if the cathode didn't have a bypass cap then there could be some feedback, but the cathode does have a bypass cap. Surely the resulting effect would be the capacitance between the two wires shunting high frequencies to earth via the cathode bypass cap?

If the impedance of the cap were to negate bypassing high frequencies to ground then effect would be to reduce the high frequency response of the amp, though this would probably be limited to reducing parasitic oscillation?

I'm thinking most people normally have the wiring pressed against the chassis, surely this would result in a small Pf capacitance value to earth?

So between these two subtle effects (given the capacitance surely would be around the 10 to 22pF value.) I can't see how anyone would hear an effect from moving this wiring around.

I will have to experiment with the amp to see if I perceive of any tonal changes.