"An old distortion you may have missed, but Billy Corgan didn't"



The GT D-II distortion rack effect module compares to the MXR Distortion II, a quirky, often bassy drive that didn't achieve much fame until Bill Corgan figured out how to get great tones out of it.



The MXR Distortion II was produced in the late '70s to mid '80s.  It was designed to sound like a 4x12 cabinet full of Celestion speakers being pushed by an overdriven amp.  While many MXR pedals have been re-issued, the Distortion II has not.  It is a sleeper pedal that gained some popularity when Billy Corgan used it on the Siamese Dream album.  It's a bit finicky, most finding it too bassy.  Others find it provides a great smooth and creamy overdrive sound, particularly with the Tone up and Resonance down.  It has a unique circuit design, unlike any other.  The signal splits into two different distortion paths which then get blended back together.  Our D-II design stays true to the audio portion of the circuit, and offers a couple of options that can give you some additional distortion options and improved tone control.



  • D-II - compares to MXR Distortion II



Input buffer



  • Original Filter - The original Filter control provides a wide range of bassy tone.  The settings that allow more treble through are all bunched up at the end of the range of control.  By default, we change this so there is better control of the adjustment.  This doesn't affect the overall range of tones, just how the control spreads them out over its range of motion.  This option gives you the original behavior.
  • Custom Op Amps - The original circuit uses three op amps.  The first one is a 4558 for the input buffer and Drive section.  TL072 are used for everything else.  If you prefer some other pin-compatible op amps, we can substitute them.
  • Clipping - There are two paths through the circuit, each with its own clipping section.  The default is to use a pair of 1N4148 diodes in each path.  This option allows you to change the diodes on one or both paths.  Red LEDs generally sound pretty good in overdrive clipping sections.  Germanium diodes tend to reduce volume, which can also make the tone sound a little smoother with less highs.  Since this isn't a very loud circuit and some find it bassy to start with, you may want to avoid them.
  • Clipping Switch - This option allows you to switch between 2 sets of diodes on each path or just one path (one switch for both paths together)
  • Dual Clipping Switches - This option allows you to switch between 2 sets of diodes on each path or just one path, but independently of each other (one switch for each path).
  • Increased Volume - The normal range of volume is OK, but if you want to get a larger volume boost we can make a simple adjustment to give the Output control a higher range of volume to work with.  As a side effect, you may get a bit more distortion available at the higher volumes.  The extra volume and any extra distortion will be more "modest" than "big".
  • Components - We use metal film resistors and a selection of capacitors that provide good tone and low noise. 


Front Panel

  • Drive
  • Resonance
  • Filter
  • Output
  • (optional) Clipping switch
  • (optional) 2nd Clipping switch


Rear Panel

  • Audio In
  • Audio Out
  • On/Off Footswitch
  • On/Off Override
  • DC Power
  • DC Power LED


Module Width

  • 1.5" standard
  • 2.0" with Clipping options
  • 2" left wing available for standard 4-control configuration
  • 1.5" right wing available for standard 4-control configuration


Power Consumption (aprox)

40 - 45mA


Base Configurations

Part # Description List Price
MOD-DII D-II module $199



Part # Description List Price
MOPT-DII-FILTER Original Filter Control $0
MOPT-DII-OPA Custom Op Amps $0 - TBD
MOPT-DII-CLIP Change Clipping Diodes $0 - TBD
MOPT-DII-CLIP1 Change Clipping Diodes, add 1 switch $19 - TBD
MOPT-DII-CLIP2 Change Clipping Diodes, add 2 switches $39 - TBD
MOPT-DII-VOL Increased Volume Range $0
MOPT-DII-CC Component Changes $0 - TBD



Part # Description List Price
MPT-DII-CA Replacement pot, switch, jack, LED cable assembly $19
MPT-DII-KNB Replacement control knob $2
MPT-DII-PB Replacement power board $29
MPT-DII-SB Replacement switching board $29