Discussions on the topic @ Vinyl Asylum:
Anumber1 @ the VinylAsylum helped me
with this. He said:
"...we changed the 47.5 ohm resistor on the grid of V4 (R29,
right channel) leading to the Volume Control pot to 1k ohm. You would
need to do the same for the left channel (V5 IIRC).
The Whistling/Microphonics are not really bad tubes but a parasitic
oscillation that occurs due to the zero feedback design of the circuit.
If you have tubes that will not work now they may be viable after the
resistor swap. IIRC the job took me less than 20 mins to accomplish so
it 'aint "Rocket Surgery".
I took his advice and it only took 20 minutes. Dead quiet now.
For reference here is
the entire board and
for the PV10B. It applies to the PV10BL minus the phono stage.