Gear Review: MXR CSP104 Distortion Plus (SCRIPT)

In April of 2011 the Dunlop Blog featured an article on an upcoming project by the MXR Custom Shop— In addition to the hardwired vintage re-issue ‘script’ phasers already offered, a script re-issue of the Distortion Plus was in the works. Dunlop continued the production and released the CSP-104 Script Distortion Plus as a UK only release, although Dunlop tech service has assured me the vintage re-issue distortion plus will make a domestic debut some time later this fall. I, however, could not wait, and ordered my unit from a gear shop based out of Manchester. 

Dressed in a mustard yellow finish, the CSP-104 has vintage Switchcraft audio jacks, CTS Pots, and a Carling footswitch. Like the original ’73-74 model this Dunlop re-issue is hardwire bypassed and completely hardwired to an old-school style PCB by the MXR custom shop. Also true to the original design, the circuitry is identical and based around the LM741CN op-amp, is powered only by a 9 volt battery— and the timeless “Hand Built by Guitar Players” is still prominently shown on the circuit board. Unlike the current M-104 Distortion Plus, the housing is not the heavy die-cast metal case we’re used to with modern MXR pedals, but rather a lighter throw-back anodized aluminum “bud box” style— not unlike the Custom Badass ’78 Distortion which results in a significantly lighter pedal compared to the block logo M-104, and a much more durable paint job. 

On the inside, the vintage style PCB takes up a bit more space than that of the modern version, which is wrapped in thick cushy styrofoam to protect the hand soldered connections. The CTS potentiometers connect to thick plastic control knobs via screw-lock, which is a nice touch to add as an alternative to the somewhat flimsy press-on knobs of the standard. The vintage switchcraft jacks push the feeling of nostalgia, but price for tradition is a sacrifice for stability— fiddling with 1/4” connectors inside the input/output jacks can sometimes add a bit of scratchiness or cut signal when the tips misalign with the circuit: this probably means it’s not the most auspicious idea to kick this one around at a gig ( usually not something the MXR custom shop overlooks ). 

The CSP-104 Distortion Plus features upgraded parts and assembly from the standard M-104, which gives it a smoother, non-brittle signal breakup in comparison. As expected, the OUTPUT knob controls the total output gain, and the DISTORTION knob adjusts the amount of clipping. Increasing the OUTPUT will also affect the frequency shift and tone, cranking the output gain will fill up the mids into fuzzy bliss. Since the current M-104 circuit is so close to the original, the character and functionality of the CSP-104 is for the most part identical. The pro’s of this re-issue are definitely the hardwired vintage PCB and vintage components, which create a smooth fluid drive ( the M-104 substitutes certain components for modern equivalents, producing a more treble focused and harsh tonality ). For a fan of vintage distortion plus users like Murray, Garcia, and Rhoads you’ll love to have this on your pedalboard replacing the M-104; being a cheaper and more available option to finding a vintage relic.