Negative supply rail

[TUBEDUDE]

Anyone here have experience using a negative supply voltage on the phase splitter cathode to get better gain and linearity?

[strelok]

Yeah on Hifi amps its pretty common. Add a constant current source in series with the cathode and negative supply for more linearity and increase of the differential effect (assuming your using a long tail/differential pair for the PI).

[TUBEDUDE]

I've seen it in an old Glass Audio from the '80s. I've used the constant current source but never the negative supply. it seemed some amps might benefit from a higher voltage differential on the P.I. than voltage available at the power tubes plates. Good strong drive from the P.I. yet lower voltage on the outputs.