PS-1 Phase Shifter

The Maestro PS-1 Phase Shifter is a vintage effects device that made a significant impact on the sound of electric guitars upon its release in the 1970s. The PS-1 is a six-stage phase shifter that utilizes Field Effect Transistors (FETs) as tuning elements for six cascaded all-pass filter networks with the input and output summed. It features three internal screwdriver type trim pots (potentiometers) for FET Bias, Oscillator Amplitude, and Output DC Offset, which were preset at the factory and should not need further adjustment. The PS-1 has three colorful buttons on the top of the unit for selecting phasing speed - SLOW PHASE, MEDIUM PHASE, and FAST PHASE. The SLOW PHASE button also functions as the bypass switch. Additionally, the phasing speed ramps up or down when changing from one speed to another, similar to a Leslie rotating speaker cabinet, providing a dynamic effect.

The PS-1 Phase Shifter is AC powered and uses a non-polarized AC cord. It features a switch on the top of the unit for power control and a fuse on the rear of the unit. The unit is designed as a table-top type, with the chassis made from bent sheet metal and a thick plate welded to the bottom of the unit, threaded for a standard microphone stand for convenient placement near the guitarist on stage. There is also an optional three-button footswitch that duplicates the operation of the three buttons, providing remote foot control of the phaser.

The Maestro PS-1 Phase Shifter was initially released as the PS-1, then evolved into the PS-1A, and later an additional Variable Speed control knob was added on the top of the chassis, resulting in the PS-1B, which was the final version of the PS-1 Phase Shifter. The PS-1A version was the most produced among the three versions.

It's important to note that the Maestro PS-1 Phase Shifter, like most effects of its time, does not include True Bypass Switching, which causes a noticeable reduction in high-end brilliance when the unit is in bypass mode (phasing off). This effect is due to the unit's design and should be considered when using the PS-1.

The Maestro PS-1 Phase Shifter is a vintage piece of equipment, and any modifications or adjustments should be approached with caution, as the unit contains potentially lethal voltages and delicate internal components.

For the most accurate and up-to-date technical specifications, it is recommended to consult the manufacturer's official documentation or authorized sources.