Build - Pedal Project: Distortion+

The MXR Distortion+ is a classic op-amp-driven distortion pedal. The original used an LM741 op amp for gain with silicon diodes for clipping. The origin of this circuit topology in guitar pedals is debated, but the MXR Distortion+ was certainly one of the earliest, and the simple circuit used in the Distortion+ is the basis for a very large variety of distortion pedals that have been designed since. Newer distortion pedals will often include a tone control, which is noticeably absent on the Distortion+. The simplicity of its bare-bones circuit makes it a great candidate for a turret board build, and it is an iconic pedal for a reason, having been used by Randy Rhoads, Jerry Garcia, Thom Yorke, etc.

The original pedal used an LM741. Metal can versions of this op amp can be difficult to find and expensive these days, but this build will also work with Alfa AS301AH, which is a relatively inexpensive metal can op-amp that is currently in production.

Figure 1: Turret board layout of the Distortion+.

Figure 1: Turret board layout of the Distortion+.

Figure 2: Distortion+ Schematic

Figure 2: Distortion+ Schematic

Parts List

ValueQtySKUType
Capacitors
10 nF1C-MKT-D01-400Film Cap
1 nF2C-MD001-630Film Cap
1 µF1C-ET1-50-MODElectrolytic
47 nF2C-MKT-D047-400Film Cap
Potentiometers
10k Audio1R-VAM10KA-SSVolume Control
1M Linear1R-VAM1ML-SSDistortion Control
Resistors
10 kΩ2R-I10KCarbon Comp Resistor
1 MΩ3R-J1MCarbon Comp Resistor
4.7 kΩ1R-I4D7KCarbon Comp Resistor
Semiconductors
1N41482P-Q971Silicon diode
AS301AH1P-Q-AS301AHOp amp
Other Items
2x61P-HTBU-2X6-DBoard
Black 1590BB1P-H1590BBEnclosure
Black 3PDT1P-H501-L-BLKFootswitch
Black/red LED1P-LPW-FLATBK-RPrewired LED
Lumberg switched DC jack1P-JBLB-IN-SDC jack
Mono jack1W-SC-111XOutput jack
MXR-style knob2P-K345Knob
Stereo jack1W-SC-112BXInput jack
Note that the information presented in this article is for reference purposes only. CE Distribution makes no claims, promises, or guarantees about the accuracy, completeness, or adequacy of the contents of this article, and expressly disclaims liability for errors or omissions on the part of the author. No warranty of any kind, implied, expressed, or statutory, including but not limited to the warranties of non-infringement of third party rights, title, merchantability, or fitness for a particular purpose, is given with respect to the contents of this article or its links to other resources.