hiwatt inverter as LTCC

[Andy Le Blanc]

Is there a good reason not to treat the inverter typical of a hiwatt the same
as any cathode coupled long tail inverter with a coupling cap on the input grid?

It seems to work on the bench, I'm thinking there might be a bias issue.
Maybe supply a fixed bias source? I saw similar in a wem scheme.

[Andy Le Blanc]

yep... the cathode voltage is very low compared to schematics.
There's also an impedance issue, there usually sourced from a follower.
but the whole thing is too similar to regular cathode coupled inverters'
you see them directly coupled to a plate circuit in several HI FI.

There's a WEM Dominator that fixes the this with a "shared anode input mix",
so instead of fixing only the input grid voltage with a resistor divider,
it splits the resistor going between the grids of the inverter, and applies a positive voltage there. Its a two or three resistor fix....

[Andy Le Blanc]

Happy mistake, the thing sounds good clean too. Something different.
I'm still going to have invest some noodle time on the bench with it.
Still have to see how it likes being over driven, AC/DC balance etc.

[Andy Le Blanc]

All that to end where I started, trying to simplify the circuit with a fixed bias
wasn't practical, nice clean at a low volume, but nothing compared to driving
that inverter with a follower, impedance makes all the difference.
I don't think how you get the low impedance is too critical.
A simple follower, like a bassman or marshal, or voiced with the hiwatt values,
I'd like to try a SRPP next....

[Andy Le Blanc]

This one sounds huge, big phat clean. You can gain it up with tube type selection.
But I think the current handling of 12au7 and 12at7 might be more important.
This sounds like it would make a good foundation for an acoustic/bass/keyboard/jazz guitar.
I've got 2 12ax7 gain stages before it. A gain control after the first, and a
tone stack and master vol. after the second. Looks like the pre amp configuration
will be really flexible. Fender 50w opt and pt, cathode bias, looks like the
powerside can be flexible too.

funny start to the thread, end with a happy mistake, cant wait to gig this one.