Didn't want to bug Mark GGG Envelope Filter cap switch - HELPPP!! AAHHH

[boogietube]

Here's what Mark Hammer wrote me concerning a multiple range filter selector switch for the GGG MXR
envelope filter
I want to have three values for the switch Guitar bass and more bass?

Could anyone draw a diagram as to how this would work?

I just don't visualise this.

Here it is:
the mod for 3 ranges involves using 2 caps in series to replace what JD
has shown in the unrepaired schematic (not sure if he changed it after I
drew several errors/mods to his attention) as C6 and C7.  So that's 4 caps
altogether, instead of 2.

Imagine that you now have 2 caps in place of C6 and 2 in place of C7.
Using a DPDT 3-position switch (may set you back $6 in town here), imagine
you run a wire from the junction of each cap pair to the centre lug of
each set of contacts on the switch.  Now run a lead from the one end of
each pair (let's say from pins 1 and 13 on the schem) to the leads at one
end of the switch, and run a pair of leads from the other side of the
filter sections (pins 2 and 12) to the other side of the switch, making
sure that the wires from each filter section make it to the same side/half
of the toggle (i.e., same group of 3 solder lugs).


Okay, when the switch is in the middle position, each pair of caps is in
series, and is equivalent to a cap with the value 1/C = 1/Ca + 1/Cb (so
1000pf and 2200pf in series equals 687pf).  Flick the switch to one side
and one from each cap pair is shunted, making C = to the remaining cap.
Flick the switch the other way, and you do the opposite.  This will yield
3 ranges from just 2 extra caps....pop-free.

Actually, 1000pf and 2200pf might not be bad values to try.  1000pf is
stock and good for guitar or baritone guitar. 687pf bumps it up into the
Dr. Q range, and 2200pf bumps it down an octave to make it more suitable
for bass.
THERE'S NO WAY I UNDERSTAND THIS WITHOUT A PICTURE.
AAAAHHH!

[23]

I know this is old but I would like to see this drawn out as well....

[scratch]

I did this up in paint ... the dashed lines at the top represent the switch positions, up/down (left/right), and centre,

in one position you short one capacitor, in the other position you short out the other capacitor, in  the centre position (off), you short neither ...

[scratch]

sorry about the picture size ...

[Mark Hammer]

Thanks Denis.  That's it exactly.   

If you need a center-off DPDT, Sean, I bought a bunch from Tayda.  I'll carry one on me next time I visit Long & McQuade's. (private joke, there)