simple guitar amp ?

Ahh, at last a topic I can contribute to! :)

A Zen amp should do fine - for the power amp stage. You will want to provide additional amplification for the guitar signal to bring it up to a level that can drive a Zen.

Typical guitar amps have a sensitivity on the order of 50 mV for full output. Line level is around 1 V, so you need to provide a voltage gain of roughly 20. For a simple design, try a JFET common-source stage followed by a JFET or MOSFET source-follower as a buffer. You can't get much simpler!
 

wampyr32

Member
2002-02-07 2:35 pm
Chucko,
can i power the preamp with the Zen's power-supply (maybe through a voltage regulator ) ?
Will the Zen distort nicely when overdriven ?
Can i use a cpu heatsink with cooling fan to cool down the transistors ?

Chucko said:
Ahh, at last a topic I can contribute to! :)
Typical guitar amps have a sensitivity on the order of 50 mV for full output. Line level is around 1 V, so you need to provide a voltage gain of roughly 20. For a simple design, try a JFET common-source stage followed by a JFET or MOSFET source-follower as a buffer. You can't get much simpler!
 
I haven't built the Zen, so I can't comment on how it sounds. My best guess is that it would sound a bit like a tube Class A amp, e.g. a Fender Princeton or comparable.

You could certainly power the preamp stage from the Zen's power supply. Most commonly available JFETs will only handle about 30 volts. A simple 3-terminal regulator or even a Zener diode can do the job, the current involved is not very large, maybe a few mA.

I personally would not want a fan anywhere near my guitar amp, especially if I wanted to record the output! Use a big honkin' heat sink from your local electronics surplus store.

If you intend this amp to work at "bedroom" volumes, you really only need a watt or two. Driven into power amp distortion, 10 watts with most guitar speakers can get very loud! Start small and scale up if you need more volume.