Tinkering with Jfets

[doitle]

I saw a post on R.G's website about JFET circuit design and started playing around a little bit with the simple JFET amplifier circuit he provided. Putting a second one immediately afterward and simulating it. It seems like with such a simple little circuit you can really get some blasting high gains. I was gonna go to Radioshack tomorrow and buy two J201 JFETS since I looked through all my bins and I have no JFETs. Would there be any danger involved here to the JFETs or to my amp following this pedal? I was speculating 10mv input signal as the guitar. I don't have any fancy pickups, standard Ibanez V7 and V8s. It looks like it can produce 6V p-p output at max gain and "crank". I just wanted to make sure before I breadboard this thing and wind up damaging anything. Here's the schematic I'd be working off of. Also any comments about it would be great as I am just starting to learn about JFETs.  I'd suspect they are similar to MOSFETs perhaps as far as design equations and the like go? We learned about them in my circuit theory classes but we never mentioned "JFETs".

Schematic:


The "gain" pot is a 20K linear and the "crank" pot is a 40K linear.

Simulation:


Also shedding some light on the potentially clipped off bottom half of the signal would be neat too. It could just be this simulator screwing up but I don't know for sure until I dive into Sedra and Smith and see if it has some material on JFETs.

[Auke Haarsma]

you will most likely overdrive the preamp of your amp. No harm there.

When simulating a guitar signal I often take 100mV at ~1k Hz, for passive pups. I think 10mV is too weak.

[GibsonGM]

+1 on 100mV.  The distortion might sound nice )

[petemoore]

The "gain" pot is a 20K linear and the "crank" pot is a 40K linear.
  I used to tinker with Jfets, but I called these pots 'bias trimpots', sometimes even 100k wouldn't do it either, depends on which Jfet of course.

[CynicalMan]

you will most likely overdrive the preamp of your amp. No harm there.

When simulating a guitar signal I often take 100mV at ~1k Hz, for passive pups. I think 10mV is too weak.

I often use 500Hz at 300mV or 500mV or even over a volt if I'm designing a clean effect. I also suggest using a pickup model like the one here.

[Caferacernoc]

The clipped waveform you see on one half is because this circuit produces what is called assymetrical clipping. If you keep increasing the input voltage you will see it clip more and more. And then the other side will start to clip too when you really hit it hard. A humbucker puts out almost a volt for the first few milliseconds of a sharply plucked string or strummed chord.