ODS 1 & 2 Optimum Plate Voltage 6SL7 vs 12AX7

[David Root]

I've been playing with a modified amp that I took the reverb out of and replaced it with a low plate ODS circuit.

All the preamp tubes are 6SL7s not 12AX7s. I had what I thought was a fairly decent OD tone with about 185 Vp, after I added a tube and paralleled both OD1 and OD2 in order to get the same gain level as a single triode 12AX7.

Then I upped the plate voltages to ~200 by increasing Vp from 330 to 370V. This increased the clean swing dramatically over the standard 12AX7 swing with 200Vp, and I had to jack up the OD entrance and the ratio to compensate in order to get some singing tone. Current increased from about 1.7 to 2 mA (paralleled), which is not a lot and is comparable to the clean section currents.

I'm wondering if I have overdone Vp on the parallel 6SL7 vs the standard 12AX7? The 6SL7 is a lower plate resistance. This is a 100W amp, bigger glass, and I have yet to crank it in the new arrg't (wife has to go to the supermarket before I can do that).