Circuit Help

[Fangda]

K so im trying to design a distortion/active boost to put directly into my trebel or bass (still havent decided). Right now, ive made the following circuit with both soft and hard diode clipping for distortion.

          ___
       .-|___|----------.    -----------------------------o------+ 9 V
       |                |   |                             |
       | T              |  .-.                            |
       |---  ___    .->|o  | |                            |
       -o oo|___|---o   |  | |                            |
       |   |  A      -|<o  '-'   +[/                      |  Signal Out
       |   '--'         '---o-----[|------o---------------o----o----.
       '----------.         |     [\      |    .--o----.  |    |
                  |       |/            | o    |  |    |  |    |
    o-----------o-o-----o-|           |=|>     | .-.   | .-.   |
 Signal In      |         |>o           | o    | | |<--' |||   |+
                |           |             '----' | |     |||  ===
               .-.         .-.                   '-'     '-'  /-\
               | |         | |                |---o---|   |    |
               | |         | |                V       -   |    |
               '-'         '-'                -       ^   |    |
                |           |                 |       |   |    |
   o------------o-----------o-----------------o-------o---o----o--|
 Ground In                                                       ===
                                                                 GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Im somewhat unsure of what values I should use for some of the resistors (and the pots), but its based off of this preamp - http://www.till.com/articles/GuitarPreamp/ -, with the distortion circuits added in by me.

Any help would be appreciated!

[Toasted]

You'd be better asking over on DIYstompboxes

[mikeboth]

That ASCII schematic is practically impossible to read; a hand-drawn one would be better.

[niftydog]

Well, for starters 9VDC seems to be directly connected to the output, so that's not gonna work too well! I'd suggest you rejig the drawing a bit to reduce clutter - like do you really need the speaker symbol, and whatever that is next to it? The clearer it is the easier it is for others to understand and the more likely they are to help.

ASCII schemes can be readable! Just take a bit of care.

+1 for DIYStompboxes too. Just be warned, I had to stop going there regularly because I was coming up with too many project ideas and wasting too much time!

[Fangda]

Lol thats a cap, not a speaker =D
and yeah, ill prolly draw it out by hand, this ascii thing uses unconventional symbols that are nigh impossible =/
ill get it up soon as I have time, big bio final tommorow =(

[niftydog]

Precisely my point! In ASCII circuit, avoid the symbols where they try to get too tricky and you'll be fine. For example, forget about the polarised cap symbols, just use regular cap symbols, they're much cleaner. Then things like the resistor connected across the first clipping stage - that's actually just going from collector to base so rather than plonking it up the top there in no mans land, put it down close to the transistor.

[Fangda]

Here, I just did it up on paint, much neater =D

[niftydog]

Ah, it's a FET now! Well, that changes things a bit! JFET or MOSFET? Still seem to have 9V connected to the output.

[Fangda]

Its JFET, and opps...
The wire from +9V to the resistor should be to the cap, just move it a smidgeon to the right...
Im just copying the FET from http://www.till.com/articles/GuitarPreamp/ and adding hard and soft clipping to it, so i presume that its supposed to have a 9V going to out =/

[niftydog]

Ah ok, I think the cap is just filtering across the power supply - it's not connected to the output wire.

I see no reason why you couldn't start with the resistor values as shown in the link. Then the pots will depend on the relative impedances at those points in the circuit, so for the input side you might need... I dunno, bit of a guess... something fairly high like 2M or something - would depend on the value of that resistor at top left. Output side I'd start with 50k - might need to go higher. Start by dropping in resistors and experimenting with the values, that should give you a good idea of the range of adjustment you need.

[Fangda]

oh, so the the cap is NOT connected to the output? =/ it would help if the schematic I was looking at had a broken line or something to signify that, heh
kk, ill try out those values you recommended, and ill toy around with different resistors, as you said, before I buy a pot (10 cents as opposed to 2 bucks...)