This hard-to-find effect pedal has been a favorite of mine for years. I haven’t been using it for quite a while though, so I’ve decided to part ways with it.

This unit is in excellent working condition, although there are blemishes on the chassis from years of use. Even though it wasn’t designed for use on the floor as a footswitch, I’ve found that it works quite wonderfully in that capacity.

Photos of the Actual Item:

Product history provided by a very informative webpage dedicated to the Maestro PS-1 Phase Shifter:

“Maestro was the name used by Gibson to market its innovative line of guitar effects boxes during the 1970’s.

“The PS-1 ruled as king of the phasers for quite some time, and although it was eventually replaced by units that were smaller and less expensive, the Maestro PS-1 remains unique in many ways. In fact, the Maestro Phase Shifter has never really been equaled. Even today, it continues to be championed by loyal enthusiasts, and some thirty years after its release, the sound of the Maestro Phase Shifter can still be heard whirling and swirling on new recordings.

“The Maestro Phase Shifter was not intended for floor operation; rather, it was designed as a table-top type of unit. The chassis is made from bent sheet metal. The top of the unit is slightly angled for improved visibility of the control panel. A rather thick plate is welded to the bottom of the unit and is threaded for a standard microphone stand; in this manner, the unit can be attached to a mic stand and conveniently placed near the guitarist on stage for easy access to the controls. A six-pin Molex type connector located on the rear of the unit provides connection to an optional three-button footswitch that duplicates the operation of the three buttons, providing remote foot control of the phaser.

“Three colorful buttons located on the top of the unit select the phasing speed. The buttons are appropriately labeled SLOW PHASE, MEDIUM PHASE, and FAST PHASE. The SLOW PHASE button also functions as the bypass switch. One unique and very cool aspect of the Maestro Phase Shifter is the fact that the phasing speed ramps up or down when changing from one speed to another, similar to a Leslie rotating speaker cabinet. This feature is not to be overlooked or underemphasized!!! The dynamic effect produced by the ramp-up/down feature sounds absolutely superb when used by an accomplished musician – no other phaser offers this feature and that alone makes the Maestro Phase Shifter worth the price of admission!

“The Maestro Phase Shifter is AC powered and uses a non-polarized AC cord. A switch on the top of the unit turns it on and off. A fuse is provided on the rear of the unit. The classic Maestro emblem with its three colored “trumpets” is proudly displayed on the top of the unit.

“The PS-1 is a six-stage phase shifter. It utilizes Field Effect Transistors (FETs) as tuning elements for six cascaded all-pass filter networks with the input and output summed. An LFO modulates the FET control buss and includes a time constant so that when the LFO speed changes, it ramps up or down slowly, simulating the speed change of a Leslie speaker cabinet.

“Initially, the Maestro Phase Shifter was released as the PS-1. Shortly after its release, it evolved into the PS-1A. Later an additional Variable Speed control knob was added on the top of the chassis and the unit became the PS-1B. This was the final version of the PS-1 Phase Shifter. There were far more PS-1A versions produced than either the PS-1 or PS-1B versions.”