[quote name='Pollinator95' timestamp='1313850410' post='1346413']
Some bass preamp (I don´t think it´s commercially available. It also has JFETs)
[/quote]
Hey all, first post here, anyway... fancy seeing my schematic posted here. I know this is an old topic but I just wanted to chime in. For anyone interested, this is essentially the FET-2B project posted at a DIY forum, but with modifications.
First, I designed my version to run on 18V for higher headroom (clean signal before clipping), also, higher output voltage (volume). The output of my version can drive the input of a power amp.
Second, I'm using J305 jfets instead of J201. The J305 has a higher V[sub]gs(off)[/sub] than the J201, which means the J305 can take a larger input signal before clipping.
Third, the tone stack i'm using is based on the Marshall tone stack topology instead of the Fender topology.
Fourth, instead of trimmers to set the fets drain voltage, the required drain and source resistor values are calculated for each fet for optimal biasing. This biasing method is based on the Fetzer Valve project at runoffgroove and Dimitri Danyuk's Triode Emulator paper.
So there you have it. BTW, I have since taken this schematic down as I have made some changes to it.
