J201 JFET Alternative

[rock94]

I want to build the Tillman guitar preamp which uses the J201 JFET,but I'm unable to find it anywhere.Even the 2N5457 isn't available.Anyone knows any other replacement which works well? Or any other simple guitar preamp design.
Thanks.

 

[keith1200rs]

If you are happy with surface mount the MMBFJ201 is still made so could be available, depending on where you are.

Keith

 

[FvM]

J201 is still made by interfet.

 

[rock94]

I have the bf245 jfet?Will it work?

 

[FvM]

Referring to the simplified quadratic model, JFETs can be characterized by Vgs and Idss. BF245A Vgs is in the same range as J201, Idss is considerably larger, transconductance respectively, too. So it depends on the circuit, if BF245A works well.

Regarding Tillman's amp, the author refers to 2N5457 that's been working in the same circuit, it's more similar to BF245A. Following a quick hand calculation, BF245B and BF245C would require an increased source resistor value to avoid saturation. Checking the operation point with a multimeter will tell, there should be at least 2V Vds voltage drop, better 4V.