MXR Distortion Plus

The MXR Distortion+ was designed by Keith Barr (former President and co-founder of MXR Innovations) in the early 1970s and it has definitely made it's mark in the history of music since then, proving its status as one of the great classics in the expansive distortion world. Great guitar legends like Randy Rhoads (Ozzy Osbourne) and Bob Mould (Hüsker Dü/Sugar) have made the Distortion+ part of their trademark guitar sound and it has found its place on countless recordings throughout its almost 40 years history, musically ranging from mellow pop music to hard rock/heavy metal. Slightly deviating from what the name "distortion+" would let you expect, the sound of the pedal is more an overdrive-type of sound ranging from low-volume mild distortion, over to a warm, tube-like overdrive, all the way to a crunchy, pronounced fuzztone with lots of sustain with the controls maxed out. The versatility of the sound is amazing considering the simplicity of the unit, producing a variety of sounds suitable for various musical styles from classic rock to scooped heavy metal. As for the company behind this pedal, MXR (MXR Innovations) was one of the most proficient manufacturers in the effects industry in the late 70's and early 80's, playing a central role in creating the industry of electric guitar effects as we know it today. MXR was the largest US effects company and their original pedals and rack gear are still highly sought after today, neary 35 years later. In the mid 80's, despite it's strong market position MXR was hard-pressed due to the incoming wave of effects from the far east (i.e. Boss and Ibanez), and was forced to give up the manufacturing of effects pedals in 1984. The same fate became also Electro Harmonix, who was propably the strongest US rival at that time. In 1987 the MXR brand was purchased by Jim Dunlop, who started making reissues of the old line of effects and bringing new effects under the MXR brand to the market. Here some of my favorite mods that I like to make to this type of circuit: • Use an SPST switch to insert a .01uf cap in parallel with a .001uf cap in place of C2. This will give a ''more/less compression'' type of function, or a ''smooth/open'' tonality. For a more dramatic effect, make the .01uf a .047uf or so. • Add an SPST switch around C3 to add more bass by adding a .33uf cap in parallel with C3. • Change R2 and C3 to a 1k/.22uf for the same high gain frequency response but more gain potential • Change R4 to a 1m audio taper pot for better response through gain adjustment. • Add an SPST switch to add in diodes in parallel with R4. I have 1n34a and 1n4001 diodes shown here, though any can be used. • Change D1 and D2 to 1n34a and 1n4001 diodes (in series) in place of each stock diode for louder output as well as better dynamics. • Change C5 to a .0022uf and wired in series with a 1m audio taper pot to act as a tone control