Pigtronix's EP-1 ($280) footpedal is a 4-stage analog phase shifter that offers envelope-controlled phasing and rotary phasing reminiscent of the classic
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Pigtronix's EP-1 ($280) footpedal is a 4-stage analog phase shifter that offers envelope-controlled phasing and rotary phasing reminiscent of the classic Uni-Vibe pedal. A trigger input lets the unit accept a sidechain signal for effects such as rhythmic phase modulation. Several controls and an expression pedal jack let you tailor the EP-1's sound for multiple applications. The pedal sounds fat and expressive, and musicians should warm to its sound.

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Pigtronix''s EP-1 features a trigger input that can be used to let input signals be phase modulated by external audio sources such as a drum machine.

The EP-1 uses an asymmetrical relationship of capacitors to simulate the high- and low rotors of a Leslie cabinet. Most phase shifters are composed of a comb filter with symmetrical notches, so that phase shift occurs at a single crossover frequency. The EP-1 spreads the phase-shift crossover across the frequency spectrum, which can yield more dramatic lows, juicier mids, and clearer highs than symmetrical phaser designs. The unit also uses opto-isolators to create the phase-shift effect and contribute to the unit's clean sound.

Housed in an oblong-shaped, roadworthy metal chassis, the EP-1's main controls are divided into three sections. The Envelope Follower/LFO section has sensitivity and sweep knobs and an EF/LFO footswitch. The Phaser section contains knobs for resonance, speed, intensity, and character, along with an invert footswitch. The Engage section enables you to activate or bypass the main input of the EP-1.

The back panel sports ¼-inch unbalanced connections for In, Trigger, Out, and Expression. Trigger allows an external source, such as a drum-machine rhythm, to control the action of the envelope follower for tricks such as beat-synced phasing. Expression is designed for use with an expression pedal that controls the LFO speed. Pigtronix makes a hefty monophonic TRS expression pedal that's designed for the EP-1 and costs $50. (Other monophonic or TRS pedals may work with the unit.) The EP-1 gets power from an AC wall-wart cable. The unit doesn't accept batteries.

In the Mode

The EP-1 Phaser section is controlled by either the Envelope Follower (EF) or the LFO. The sound clearly indicates which mode you're in, and the green LED acts as a visual reference. In EF mode, the LED responds to the strength of the signal at either the main Input or the Trigger input, while in LFO mode the LED flashes in time with the oscillator.

When EF is engaged, the Sweep and Sensitivity knobs adjust the range and responsiveness of the follower. In practice, you crank the Sensitivity knob until a phase effect is apparent. The Sweep knob is used to control the depth of the effect. The harder you play your instrument, the stronger the phase shift will be. The LED tracks that, getting brighter as you play harder.

When LFO is engaged, Sweep and Sensitivity are disabled, and the Speed knob in the Phaser section controls the LFO rate. Using that knob or the expression pedal, you can create the characteristic pulsing qualities of an LFO-modulated signal. If you want to run the EF and LFO at the same time, Pigtronix will customize the EP-1 with a “Marv” switch that allows all six knobs to interact and concoct more dramatic effects.

Phaser Set to Stun

In the Phaser section, Resonance corresponds to the amount of feedback in the phase-shifting circuitry, while Intensity is the blend of effect versus untreated signal. Both are active whenever the EP-1 is engaged. Those controls help shape the rich, tonal signature of the phaser, which never feels harsh.

While Speed varies the LFO rate, Character controls the amount of voltage going into the LFO and can actually alter the triangle wave so that it approaches a sine wave. Messing around with the Character knob, I discovered a couple of LFO sweet spots in which a warm phased sound seemed to bloom.

The Invert footswitch selects how the phased signal combines with the normal signal. When the accompanying LED is red, the phased sound is added to the normal sound and produces the classic whoosh. When the light is green, the phased sound is subtracted and yields a deeper sound. That mode was particularly useful for enhancing the bottom end in my bass lines.

No Analog Sty

There are a variety of applications for the EP-1. For rotating-speaker effects, I liked splitting the stereo output of my workstation, sending the left channel through the EP-1 before routing it to the mixer. You can also create a sidechain FX loop with a Y-cable by sending your clean signal to the Trigger and feeding the other branch through your other effects and into the EP-1's main audio input. That method creates unique textures — the envelope is controlled by your instrument's clean signal while the effects-laden signal is phase modulated.

The EP-1's sound and versatility justifies its price tag. The unit provides a rich, almost vowel-like quality to phasing effects, and speaks with a pleasing, chunky sound.

Overall Rating (1 through 5): 4
Pigtronix/Absara Audio LLC