JFET Bass Preamp

[markmcconachie]

Has anyone tried this project? Either as a stompbox or onboard?

I am considering trying it for onboard an older passive ibanez SR405...

http://www.albertkreuzer.com/preamp_onboard.htm

[egasimus]

Ah... That reminds me of how my classmates were mad at me because the classroom smelled like rosin, and how my wife-to-be lost the bag which contained my soldering iron, large roll of solder, leather bass strap, and what were my only JFETs for a long long time. I was trying to stick this circuit in an old Bulgarian bass guitar with a broken truss road, resulting in horrible fret buzz all the way to the 7th fret... Yeah, this brings memories Which are, however, completely unrelated to what you're asking.

The source resistors R2, R5 and R11 have to be selected according to the FET (and the supply voltage). Connect a 5k pot instead of the source resistor and adjust for maximum non-clipping signal at the drain. Then disconnect the pot, measure its resistance and put a resistor with the closest value available into the circuit.

If you're proficient with PCB/perf/vero layouts, i.e. you won't be building this with the layout provided there, I'd recommend just sticking three trimmers and fine-tuning.

This circuit really does call for push/pull pots But, if you're not afraid of drilling your bass, you could probably fit the full version in there, too - that layout can be made a whole lot smaller. You can also omit the EQ and keep the ultra high/ultra low switches; I've read that people don't even use the EQ much.

[markmcconachie]

I am not too experienced with layouts, but I guess i need a place to start anyway! I do MUCH prefer the idea of using trim pots.

I don't really care about using onboard EQ.

I have no issues with drilling the bass, I am a pretty experienced guitar tech

How did it sound?

[Mark Hammer]

I say just make it in memory of Albert, who sadly passed away last year.

[markmcconachie]

It makes me sad to know that.

I think that I will build it, not JUST out of respect for the man though. It seems like a pretty nice little circuit!

[Mark Hammer]

You can find some tributes to Albert over at the Music Electronics Forum.

[markmcconachie]

I will take a look, thanks.