Hey Guys,
I've been playing around with Fetzer Valve style JFet gain stages
http://runoffgroove.com/fetzervalve.htmland was wondering if there is some sort of formula or pattern that could be used to convert this to an SRPP style gain stage.
http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htmThe Fetzer is nice to control the gain with the source resistor on the JFet, but I was hoping to avoid having to use a trimmer to adjust the bias. The SRPP style booster is nice because it self biases, but in my experimentation it seems to have much more gain and I would have to really play around with the source resistor and the capacitor between gate and source of the top JFet as it really changes the overall character of the tone either more bass or less depending on the cap.
I assume there is no direct sort of conversion and I'd probably have to rely on my ears to dial it in, but I was wondering if anyone has had any experience here and if there are any sort of patterns or design decisions that would help in the conversion. Perhaps even it isn't even worth it and you need design your circuit with one or the other.
Appreciate any opinions any may have.