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.
Parts List
Value | Qty | SKU | Type |
---|---|---|---|
Capacitors | |||
10 nF | 1 | C-MKT-D01-400 | Film Cap |
1 nF | 2 | C-MD001-630 | Film Cap |
1 µF | 1 | C-ET1-50-MOD | Electrolytic |
47 nF | 2 | C-MKT-D047-400 | Film Cap |
Potentiometers | |||
10k Audio | 1 | R-VAM10KA-SS | Volume Control |
1M Linear | 1 | R-VAM1ML-SS | Distortion Control |
Resistors | |||
10 kΩ | 2 | R-I10K | Carbon Comp Resistor |
1 MΩ | 3 | R-J1M | Carbon Comp Resistor |
4.7 kΩ | 1 | R-I4D7K | Carbon Comp Resistor |
Semiconductors | |||
1N4148 | 2 | P-Q971 | Silicon diode |
AS301AH | 1 | P-Q-AS301AH | Op amp |
Other Items | |||
2x6 | 1 | P-HTBU-2X6-D | Board |
Black 1590BB | 1 | P-H1590BB | Enclosure |
Black 3PDT | 1 | P-H501-L-BLK | Footswitch |
Black/red LED | 1 | P-LPW-FLATBK-R | Prewired LED |
Lumberg switched DC jack | 1 | P-JBLB-IN-S | DC jack |
Mono jack | 1 | W-SC-111X | Output jack |
MXR-style knob | 2 | P-K345 | Knob |
Stereo jack | 1 | W-SC-112BX | Input jack |