MXR Distortion +

When did the Distortion + first appear? What is the earliest example by date codes?

Earliest example I've seen so far:

http://www.freestompboxes.org/viewtopic.php?f=1&t=10295

741 is dated '73, but pots date 51st week of '74 (end of '74) so this would most likely have appeared for sale in 1975.

http://www.freestompboxes.org/viewtopic.php?f=19&t=16971&p=187951&hilit=blue+clipper#p187951

The above post claims (no evidence presented) that the Dist + came out in 1973.

Pedalarea also claims Bud box versions were made in '73. No idea if this is fan speculation or not. Interviews suggest 1974 is the beginning, if memories are to be trusted.

Richard Neatrour (First employee of Barr and Sherwood) recalls in AMGTVE, "The first two things we started working on were the Phase 90 and the D+."

Still on the lookout for the earliest example, as no MXR history makes it clear when the Distortion + first appeared.

This is a contender for "first op amp drive + passive shunt diode clipping" alongside the Blue Clipper and the Gretsch Controfuzz/Expandafuzz. All there have good claims for 1973, although most MXR histories suggest 1974 was the release year. The MXR leads the pack in my mind since both Blue Clipper and the Gretsch effects have odd circuits that have never become popular. The Blue Clipper has a really bizarre Vref for the non-inventing input that results in extra non-linear clipping, and the Gretsch effects use a difference amplifier to subtract clean and fuzz from each other which makes for a peculiar end result. The Dist + is pretty straightforward and widely copied.

Allegations that MXR copied the Dan Armstrong Blue Clipper

Dan Armstrong makes the strong allegation that MXR copied a Blue Clipper in Art Thompson's "Stompbox." More notes on this are found on the Blue Clipper page.