Princeton Reverb PT replacement...which HV tap to use?

[Matthews Guitars]

I'm replacing a blown power transformer in a silverface Princeton Reverb. Using a Hammond 290AX power transformer, which has two HV windings.

I can choose to use the high voltage winding or the low voltage winding.


Higher voltage winding: Red - Red/Yel- Red: 650V CT 100ma
Lower voltage winding: Red/White - Red/Yel - Red/White 550V CT 100ma

Which would you recommend, to preserve this amp's most "classic" sound?

And what's best practice for dealing with the unused taps? Ground or cut back, heat shrink, insulate?

[Stevem]

The silver face amps are annoying when you look at the two common schematics for them.
They both use the same part number PT, but one uses a 5AR4 recto and one uses a 5u4.

Both schematics show the PT pumping out 340 volts of AC so that’s 680 and the B+ being shown as 420 vdc with the amp idling.

Yet a 5AR4 with its lower impedance will produce about 20 more volts of B+ than the 5U4 recto.

Both schematics even call for the same -34 volts of bias at the junction test point.

I then would use the 650 volt tap.

Just shrink rap the unused lower voltage wires and cable tie and tuck them down between the PT and the side wall of the chassis.

I would also make sure that your first two power supply filters are rated at 500 volts.

These amps seem to sound there best overall if you do not idle the outputs any hotter then .018 to .020 amps.