*Grumpy mode engaged*
I never understood how the Tillman was all that different from any of the other "cookbook" FET circuits out there. In fact, the Tillman was designed for the J201 and won't work as well with many of the more common, but lower gain/higher current FETs like the MPF102, 2N3819, 2N5458, etc. ...AND if you've worked with FETs at all, you'll know that each one is slightly but appreciably different, and stock resistor values must be tweaked for maximum performance (though the ones given may get you in the ballpark). Add to that the concepts of diode biasing, CC loading, "cascode" chaining, ad nauseum, you could be tweaking for days... or maybe it's just that way for a hopeless circuit tweaker like yours truly. *Grumpy mode abated*
Also, the LM386 just doesn't do it for me as a guitar amp power section. 1 watt in a convenient DIP-8 package is novel, but give me 5-20 watts minimum. Here's a trick: look in your old computer parts junk box and find an old ISA soundcard with a
TEA2025 (2x2.5W) or a SoundBlaster16 with a
TDA1517 (2x6W). De-solder the chip off the board, wire the Tillman/Muff output to both inputs, and put a speaker on each output (paying attention to the official Data Sheets, of course) for a low-power 'twin' with MUCH better sound specs and power handling and no additional cost. The TEA2025 can even be
bridged. Yeah, yeah, I know, the LM386 costs pennies, but hey, mo' powah, mo' fun!...
As far as the 'Open Hardware' concept, it's so far worked for the Arduino, and a
whole list of others. Read up on Open Hardware at Wikipedia:
https://en.wikipedia...Open-source_hardware 
