Distortion: variable bass response & tone control.

[jbm222]

I want to design a distortion sort of based on the Matchless simulator from ROG.  I really like the idea behind the tone controls.  I [/i]THINK[/i] what it does is limit the bass response between the MOSFET stage & the first FET stage by changing switching the coupling cap.  I haven't done the math to prove this is what it's doing.  And then you can roll off highs with the cut.

What I don't like is the huge amount of components it takes to make this.

I want to get the same effect using a single cap followed by a pot  to ground.  However, if I use the same style gain (or actually pre-clipping volume) control, I want it to have a relatively small effect on the hi-pass filter.  Basically I want to replace the whole mess between the MOSFET & the cap into the first JFET with this (hopefully my ascii schematic makes sense):

Code Select Expand


---|(-------
     |    |  
     Z    Z  
  -->Z    Z<-------
  |  Z    Z
  ---|    |
     V    V


My thinking is that the best way to do this would be using a large coupling cap & a small pot for the filter & a large pot for the volume.  If the cap is too big, it will be noisier, but if the bass pot value is too large in comparison to the volume pot, the volume pot will have significant effects.

Would maybe a 47n and 50k pot w/ maybe a 2.2k fixed resitor be good?  This sweeps the ideal cut off (ignoring loading & source resistance) from about  65Hz to about 1.5kHz -- probably way more sweep than i need, but i don't think a 10k pot would give me enough.  Then a 1M pot would bring those frequencies up some, but I could adjust for that by changing the fixed resitor in series with the bass pot (not shown in my pic).