Soldano X88R preamp

[Sensei Tim]

All,

I'm in the process of working on a JFET version of the X88R preamp from Soldano (high gain channel, of course).

Using this schematic  http://www.prowessamplifiers.com/schematics/images/Soldano%20X88R%20Redrawn.pdf i've compared it to the dr boogie/madbean chunk chunk http://www.madbeanpedals.com/projects/ChunkChunk/docs/ChunkChunk2015.pdf  and for the most part it is very similar up until the master volume.

In the schematic there are 2 extra 12AX7's after all three channels merge.  Is this some kind of output buffer?  it doesn't look like it would impact the tone at all?

Can someone please confirm?

[Frank_NH]

From what I can tell, the Soldano has a tube gain + buffer at the end, probably to account for the signal loss in the tone stack.  You could replicate this with a simple jfet gain stage (no need for the buffer) before the volume control, but I would just leave it off unless you can't get enough signal from the amp sim as it stands.  Good luck with the project!