Piezo JFET Buffer with 20V instead of 9V - Help needed

[ilcaccillo]

Hi,
I building the JFET buffer from AMZ:



The supply I have available in my circuit is 20V DC and not 9V. I can easilly drop the voltage down a have a 9V feed,
But wouldn't I have more headroom if I run this circuit with 20V?

To run it with 20V do I have to change the Biasing on the JFET or resistor values in the circuit, or can I use it as is?

Thank you so much for your help
Best regards

[Gus]

With JFETS you need to think about the voltage gate to drain.
Often you will want to keep this not much greater than 8VDC