Single Jfet amp How to calc gain?

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This is actually part of a GK 1001RB bass amp. This Jfet is in there for flavor only from what i gather. there is an op-amp before and an op-amp after so this Jfet really doesn't DO anything other then overload and change the sound. But once i started looking at the circuit i got curious as to how much gain it was providing. I didn't figure much if any at all.
 
That's a simple common source stage, for the basic euquations look in wikipedia:

Common source - Wikipedia, the free encyclopedia

R1/R2 = gain is a bit too simplified as the jfet itself does not matter at all and of course there are high gain (transconductance) and low gain parts 😉

Also, 6k in the source are a little...uncommon. You will be driving any small signal jfet near pinch-off voltage limiting signal swing. Better try smaller source resistor and smaller load resistor.

Have fun, Hannes

EDIT: just thought over your last post: sure, that's ok if you want to add sound to the circuit 😉
 
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