Resistors on OT primaries

[teemuk]

I have an adjustable NFB. Goes from 2.2K to 500K. The trem worked best for me w/o NFB

I assume the tremolo in question works by modulating bias of the output tubes (reminiscent of the 5F11)? If so, do note that negative feedback will pretty much try to eliminate all the effects of slight bias variations since it practically considers variable gain as distortion.

NFB and bias modulation do not really play all too well together.