For tube amps, its all about the following:
Placement of coupling caps so it doesnt become a microphone for the high currents supplying the filaments.
Careful attention to grounding and floating certain parts.
and a good startup circuit that warms up the the filament before operating B+ is fully applied.
SF power 1 and power 2 are wonderfully designed amps.
Just that voicing misses the mark with ultralinear.
Placement of coupling caps so it doesnt become a microphone for the high currents supplying the filaments.
Careful attention to grounding and floating certain parts.
and a good startup circuit that warms up the the filament before operating B+ is fully applied.
SF power 1 and power 2 are wonderfully designed amps.
Just that voicing misses the mark with ultralinear.