Maestro PS-1A

The Maestro PS-1A Phase Shifter, released in 1971, holds a specific place in effects history: Delicious Audio's Paolo De Gregorio calls it "the first effect to be named that way (although it was not a pedal yet!)"¹². It was a six-stage phaser³, and it arrived at the very start of the phaser's run through popular music, alongside the original Maestro Phase Shifter PS-1 from the same year.

What it does

A phaser sweeps notches through a signal's frequency spectrum, producing the swirling, jet-like movement players associate with the effect type. The PS-1A did this with six stages³, the circuit design that defines the classic Maestro sound. Premier Guitar's reviewer described the moment it appeared: "Back in 1971, nothing made heads spin like the Maestro PS-1A phase shifter"⁵.

The PS-1A was not a stompbox. Premier Guitar describes it as "a bulky external unit with the large plastic switches of the era's home organs"⁵, a tabletop box you set beside an amp rather than something on the floor. That form factor is one of the clearest ways it differs from every phaser made since.

PS-1 to PS-1A

The PS-1A was the second version of the design. Guitar World's history of the line explains that "The PS-1A is basically an improved version of the PS-1 that fixed a flaw with the input buffer amplifier that produced popping noises"⁶. The original PS-1 was created by Tom Oberheim in 1971⁴, and Premier Guitar notes it was "capable of ramping between speeds, a function that enhanced the PS-1's Leslie-ness"⁴, meaning it could glide from one speed setting to another the way a Leslie speaker does.

Where you hear it

JHS Pedals puts it plainly: "You'll hear the Maestro Phase Shifter on a lot of classic recordings in the very early seventies"⁷. Guitar World notes Maestro sold an estimated 60,000 units to guitarists and keyboardists alike during its brief four-year lifespan⁶. Country players used it too: Premier Guitar's review of Fender's Waylon Jennings phaser refers to "his 6-stage PS-1A"³, documenting Jennings as a player of the unit.

Legacy

The PS-1A's design has been revisited repeatedly. MusicRadar dates the original to "the Maestro PS1-A that dates back to 1971" in coverage of Maestro's revival²⁶. Guitar World's 2026 phaser guide notes "the Maestro Orbit is based on the first commercially available phase pedal, the PS-1"⁸, and the revived Maestro Orbit carries that lineage forward. Gearnews calls the early rack unit "among the first dedicated phaser/shifter devices"⁹. For more on the effect type it helped name, see Phaser Pedals.

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