CryBaby Sweep Capacitor Switch MOD

[Triffid]

Hello,

I am in the planning phase of adding a rotary switch to choose between different Sweep Capacitors (Cf) in my GCB-95.  The stock value is 0.01.  I plan on using a 2d5t rotary switch (Small Bear).   Does anyone have some good advice on the 5 capacitors to use?

Thanks in advance

[B Tremblay]

I found that a small change in the the value of the sweep cap had a huge effect on the sound.  For me, adding smaller caps in parallel with a larger cap worked well for unavailable in-between cap values.

You could use a .0068 or .0082 for the "base value cap" and, using the rotary switch, add in a .0022, .0033, .0047, .0068, .0082uF

You may want to experiment a bit to find the best sounding smallest and largest total sweep cap value.

I ended up liking .0133uF best (no rotary switch).  Here's the rest of my mods to my Vox V847: http://runoffgroove.com/wahmods.html

[Triffid]

Thanks... is there anything wrong with just pulling the base capacitor and switching the entire cap?

I also like your output buffer... that is next on my list of wah mods

[B Tremblay]

No, there isn't anything wrong with switching the whole cap.  But switching from .01 to .022 was a huge leap to my ears.  By adding small caps in parallel, the change can be more gradual.

Also, Gez Paton is solely responsible for the beautifully simple output buffer.  He descibed it here at the forum - I just drew the schematic, tested it, and gave it a home.

[Triffid]

Ya, I would thing that would be too much as well... What do you think of these values... (All stocked at Small Bear)...

0.0082 mf
0.01 mf.
0.012 mf.
0.015 mf.
0.018 mf.

And thanks to Gez Paton.

[B Tremblay]

Those values look perfect.

[gez]

Although I haven't built the buffer, I don't see any reason not to take an additional output from the source for 'low' output impedance should you want it.  You could just switch between the two, or have two output jacks.  Just a thought...

[Gus]

I have used dip switches and wired up the caps in a binary manner.

[Stuart]

Ya, I would thing that would be too much as well... What do you think of these values... (All stocked at Small Bear)...

0.0082 mf
0.01 mf.
0.012 mf.
0.015 mf.
0.018 mf.

You might want to use a 0.022 instead of the 0.018 to get a more noticeable change in frequency from the 0.015.

A 0.0068 will get you close to early Jimmy Page territory. Those grey wahs are very bright.

[Triffid]

So do you think these values would be better?...

0.0068 mf
0.0082 mf
0.01 mf.
0.015 mf.
0.022 mf.