1977, the year the world learned the term "lightsaber," while the bee gees sung of a fever occuring on only one day of the week, and the world's first personal computer weighed 25 pounds. a groundbreaking year to say the least, and electro-harmonix was set to make sure the ground in the guitar world was rendered to dust.

1977 also saw the release of echoflanger, the earliest example of a multi-effects pedal. through its first few years of production, echoflanger underwent design changes that eventually led to its final form, polychorus. during these years ehx hired howard davis as their chief electronics engineer. howard designed and redesigned many of the brand’s most celebrated circuits (deluxe memory man, deluxe electric mistress, attack decay, and many more). howard, possessing large amounts of genius, is responsible for the stereo polychorus circuit. in his words he, “...completely redesigned it to be far superior to the original.” polychorus is such an inventive, unique circuit that it's easy to understand how this pedal can almost solely define a musician's sound.

the yesterday effects unit shifter is a copy of the stereo polychorus. every knob turn on the stereo polychorus is matched by unit shifter. our circuit uses the same ic and bucket brigade device (bbd) chips found in the original. four modes and four knobs rule over the sound of unit shifter. modes: filter matrix, flange, chorus, and double track. knobs: width, rate, tune/delay and feedback. just like the original, unit shifter features a single input and two outputs.

polychorus has a habit of creating generation defining, time-withstanding sounds. in its newest iteration, unit shifter, it just may choose you as its next channel to move through.