Here’s Analogman’s original version of the King of Tone, a highly regarded overdrive with a few “unobtanium” diodes. It’s probably best to socket said diodes to play around with your favorite combinations. Switch A controls the 4-diode array in the feedback loop (much like a Tube Screamer), while Switch B controls shunted diodes (much like a RAT or Distortion +). Originally these were DIP switches, but it makes more sense to me to have these externally.
