Pfeiffer Phaser Guitar Pedal

Design

This phaser guitar effect pedal is modeled after the MXR Phase 90, probably the most popular four stage phaser of all time. The design uses four carefully matched JFET N-Channel transistors and TL071 op-amps to create its signature sound. With the modifications below, it is capable of both the block and script phaser sounds.

Two modifications have been made to the original phaser effect.  First, in order to gain more control of the sweep and have both script and block phaser capabilities, we added a depth knob. When the depth knob is fully clockwise, you have a script phaser, all other positions are different variations of a block phaser. The second modification is the addition of the feedback knob. This knob controls how much of the output signal is fed back into the input path. This creates a more pronounced phaser effect and makes this guitar effect pedal more versatile.

Controls

• Depth The depth knob controls the depth of the effect. When the depth knob is fully clockwise, you have a script phaser, all other positions are different variations of a block phaser..

• Rate controls the oscillation speed.

• Feedback enables extremely pronounced phaser sounds. It does this by sending the 4th stage of the phase shifter signal back into the 1st stage. This knob is what sets the Pfeiffer Phaser apart from other phaser effects. Experiment with different combinations of feedback and depth to discover some very unique tones.

• ByPass engages the pedal on/off.

Wikipedia - Phaser Effect

Pfeiffer Phaser User's Guide