Hi all,
Thank you for all your input!
I've been a little busy with work this past week and haven't been able to do much with the set. I found that if I placed a 100 ohm resistor and a 10 mF cap in parallel from the collector on the 2N3906 to ground I get a noticeable bump in volume. I think I am going to try DrM's regenerative suggestion as I'm crunching the numbers for winding a new coil to replace the loopstick, and figure adding a tickler coil to the assembly shouldn't be that much more work.
I'm still not exactly sure how to control the regeneration. Looking at old tube schematics and trying to work forward it looks like I'd put a variable resistor across the source to ground, though I don't really know what I'm doing so that might be the wrong way to go about it. Maybe it would be better to replace the 1 k drain resistor with a variable resistor in parallel with the tickler coil.
A lot to experiment with!
Also, LarryDee, I was wondering if the OPA2134 is available in a dip package or if it's only available in surface mount? I ask because I'm building this thing wire wrapped on a plank of wood, using copper plated weather stripping nails as my binding posts. For such a rudimentary method, I've found it works really well!
Cheers,
JZ