Midscoop Notch Filter in DS-2

[jeroen_verbeeck]

I'm in the midst of modding my DS-2. The next thing I want to improve is the mid-scooped feeling this pedal has.
Mark H. pointed out that there is a notch filter in there that cuts some mids.

I dug up the schematic and highlighted the notch filter (in yellow).
http://www.powerflame.be/ds2.gif

Mark told me:

"When Q10 is turned on, then it is like R32 is not there and the junction of R44/R33 goes to ground directly through the cap.  C29 determines how much of the highs and mids come through.  If you want more upper mids, then make it .01, if less, make it .0033.  C21 determines where the low end of the scoop rolls off.  It is around 720hz as shown.  You can drop that if you increase C21 to .012 or .015, and raise it if you drop C21 to .0082 or .0068.  Letting more upper mids and upper bass through will decrease the scoopiness."

It's a perfect explanation, only, I don't want the filter to tinker with my sound.
How can I remove this filter ? Or if that's not possible, which values do I use to make the scoop as small as possible ?

[Mark Hammer]

Seems to me the simplest thing to do is to: a) find C28 and lift/desolder one end of that cap, and b) lift the ground side of C21.  From the pedal's perspective that will make the path between Q13 and Q12 essentially 44k (22k + 22k) worth of series resistance, with no high end bypass and no bleed to ground.  I.E., no midscoop.

[George Giblet]

You really only need to lift C21 to removed the notch.
Q10 actually switches the notch in and out ie. one of the modes doesn't have the notch in circuit.

Because the input impedance of Q12 is high R33, R44 and C28 are benign once C21 is removed.

Adjusting C29 is beyond the scope of the notch, that component modifies the voicing of highs - you can play around with that if you wish.  Keep in mind the tone control is slightly asymmetrical anyway.