Nah, no tube. Complicates things too much and in the schematic provided, it's only used to provide gain to the rest of the circuit - the gain control is after the tube. You'd have to use an external boost pedal to get any tube clipping out of it. The clipping that happens in the Westhost preamp is just diodes to ground at the end of the circuit. In this case, it would be more of a gimmick than anything useful.
I was also going to say you could just build the preamp of the blackface Bassman if you wanted tubes, but since you don't like the Alembic, you probably wouldn't like that either. I'd imagine one of those Gring Custom tube things could be mod'd for bass. I was about to look into that, but the controls that the Westhost project provides are so useful it's hard to pass up.
