Varitone in a Box

Rather than installing a varitone on every guitar in your arsenal just to see if you like it with a given instrument, you can try one out outside the instrument itself by making a "pedal" equivalent.  Granted, the design presented here is so stripped-down that it doesn't even have a footswitch (so technically I guess it isn't a pedal), but there's no reason one couldn't add an On/Off toggle or other mods.

One advantage to this approach is that you can have a 12-position switch filled to the brim with capacitors of varying gauges.  This allows you to test out which values yield the most interesting sounds for a given instrument.  Once you settle on those caps, you can install a smaller switch (e.g., a 5- or 6-position model a la BB King's Lucille) with only your favorites and nothing redundant.

The schematic
Although you can put this circuitry directly into a guitar, I enclosed mine in a project box I'd previously used as a passive volume control/stereo mixer for the inputs to my computer's soundcard (i.e., I could prevent audio clipping when recording something).  Since I'd replaced the soundcard with a built-in input vol. control, the box was no longer required, but several holes remained in the top of the box, just in case you are wondering where those came from.

Basically, the scheme is simply that you are bridging the hot side to the ground side with the varitone circuitry. 

From left to right: 

  • positive and ground sides of the original circuit approaching the jack
  • varitone (only four caps pictured; I have 11 in mine)
  • inductor
  • output jack

See also...

  • The Jazz Box -  An extension of this idea with some additional options and capabilities.

Copyright Alexplorer.  Thanks to BH for the idea to put this into a "pedal."