Controlling VG with Rg

[Andy Le Blanc]

I'm contemplating using 6sj7, 6au6 and the ilk with higher gain paraphrase inverters, and looking the RC tables,
relative to voltage gains of 12ax7, I really just don't need all that gain.

Funny thing, saying that you don't want a lot of gain in a guitar rig.

Looking at the various RC tables, it looks like I want to go with a much lower supply voltage.
But... even then the gain looks to be too much.
I'm leaning towards gains comparable with, and then that slight range above 50-60, say 70-100 for giggles.
The Sylivania tables say that I can achieve this.
The criteria for this is highly dependent on the Rg, the load over which the VG is measured.

My thought is to add a loading resistor(s) to simple volume and tone control, or make it switchable, a select-able gain range.

I found support for this in old wards-airline and supros, dano schematics, I think even in a tone master...
Wondering if others found this to be practical approach. Its the higher % of harmonic distortion offered by the device,
that tone color, I'm more after. Just don't need all the gain. Inexpensive pentodes are plentiful.

[tubeswell]

So you don't want a 12AX7 for a phase inverter because its too gainy?

Maybe try a 12AU7 with an overall 20k-30k load, should get you lots of clean headroom and plenty of current to drive output tubes (I'm picking you'll want about 4-6V bias)

[Andy Le Blanc]

Ummm... the other way around. I was noodling with 6sn7 and paraphase inverter, but ended up finding a happy place with 6sl7. The only way to add a pentode pre to it and keep the gain structure post, is to dump the gain pre. I was thinking to use an attenuator to pad the signal but it was more interesting to explore the other end of the gain tables for the tube type. The outstanding features are the supply voltage and load that the stage "see's".
Good exercise with published RC amp tables. I hadn't explored "low gain" end of it yet. 6au6 for example, has a usable range of gains of 70 to over 300. Its easy to get excited about a big gain figure, but what does the other end look like?