JFET/Fetzer Valve Q's

[aziltz]

Is it possible to get similar gain as a SHO or Range-Master using a single-jfet stage (Fetzer Valve or similar)?

I want to make an FET Treble Booster, but I need a slightly dirty boost.


Maybe a more direct question is, are jfet's as good as BJT's and Mosfet's for single component amplifying?

[aziltz]

i did a few simulations of a BJT stage and a JFET stages like the fetzer.

seems like the BJT is capable of getting 20~30 dbs of gain (not all clean obviously), whereas the Fetzer only delivers ~10.  I know that Mosfet's will give more gain like the BJT's (look at the SHO).  I've never had this comparison explained before.  Can I get 20-30 db's out of a single JFet?

[stm]

Is it possible to get similar gain as a SHO or Range-Master using a single-jfet stage (Fetzer Valve or similar)?
I want to make an FET Treble Booster, but I need a slightly dirty boost.

Can I get 20-30 db's out of a single JFet?

Check the Omega project at ROG.  The JFET stage achieves about 30dB of gain.  If you want to get rid of the 2nd stage, replace the 33k and 68k drain resistors by a single 100k resistor.

[aziltz]

thanks sebastian.  i missed the notes about the omega being derived from a "High Gain" Fetzer Valve.  This should work perfectly.  I should have looked harder, I usually find everything I need at ROG... 

for some reason, the first time I read the Omega Page, I just assumed that the Mosfet was for clipping, when in fact its just a buffer.  Interesting.  Nice Design!