This is all about Joe Davissons JFET Vulcan high gain overdrive.
Although the schematics that can be found on the net are a few years old this is still one of the simplest to build and good sounding high gain circuits.
The original Vulcan PCB has been discontinued.
The original circuit uses J201 and does not even have trimmers to set them to the correct bias. A tonestack also would be a nice feature. Apart from this using JFETs without the ability to set the correct bias is not what you want to do 🙂
So I put this great sounding circuit on my breadboard and started to search for alternatives. And I found them!
This is a version with a versatile tonestack and contemporary easy to source and to calibrate JFETs.
As the usual J201, 2N5457 are harder and harder to get and fake transistors that are far away from the initial specifications of those transistors are seen more and more I was looking for alternatives.
This is the first circuit using those alternatives.
PF 5102 are easy to source from your electronic supplier (Mouser and other sources). In addition to that I used trimpots to dial in a working bias but found that all of the transistors were in the working range without even using the trimmers.
Of course you may find some with higher deviation from the spec, so I left the trimmers in.
Try it and experience the no-frills build of a JFET high-gain device.
For reference, the original build doc of the Vulcan can be found here: