JHS Charlie Brown

[Boba7]

Hi!

So I keep reading that the JHS Charlie Brown is a BSIAB2 with a contour pot, but apparently it's closer to a slightly modified Box of Rock (dirt section only of course).
The demos online really sound good to my ears, so I've been wanting to find out about this circuit for a little while! Only problem is it's impossible to find gutshots other than the only "official" one, so no schematic etc, but I thought it could be possible to figure out what they did to the Box of Rock.
If anyone has any idea, they're more than welcome!

So here's the Box of Rock shematics: BoR

And here's a Charlie Brown gutshot with resistor values (think I got most of them right): CB gutshot
It really does look a lot like a Box of Rock (with an added contour pot). Almost only the first stage (first SHO) seems modified.

82k, 47k, .1uf and .022uf show the contour pot is probably done like this:


And the only other differences seem to be a few resistor values in the first SHO section:

- 2k7 instead of the usual 5k1 at the drain (that would mean less gain right?)
- An electro seems to connect the first BS170 source to the gain pot, and there's another 2k7 close, so that could be a way to get rid of the noise (crackle) (like Guero explained here: fsb thread)
(I dont really know what I'm talking about, just guessing here)

What I cant figure out at the moment:
- 2x 100ks at the bottom
- 62k by the blue electro
- 150r below the 2x 22nf
- the blue electro
- the yellow cap at the top

That's pretty much all I know and don't know right now.

Oh and I found a gutshot from an old version somewhere, but I doubt it could be useful: 1st gen CB

Anyone's interested? :)

[Boba7]

Ok, got it, the first SHO is actually an AMZ Mosfet Booser as seen here: AMZ Mosfet Booster

It explains the 2x2.7k, the ceramic cap, the 2 electros, the 150r is actually a 10M  etc.

The rest is strictly the dirt part of the Box of Rock with an added contour pot (thanks to AMZ again, of course)

The only resistor that's added is r26 (100k), above the contour pot. Dont know whats going on with that one. :)