Keeley Electronics Keeley Phaser

The Keeley Phaser is an analog phaser pedal from Keeley Electronics, announced by Robert Keeley in January 2010 and priced at $249.00 at launch¹. Its distinguishing feature, as Keeley himself put it, was a first: "The Keeley Phaser is the first OTA analog phaser with tap tempo and Leslie style ramping."¹

Inside is a six-stage OTA phasing circuit, the analog design associated with lush, shimmery phaser sounds¹. Where most phasers of the era left you turning a rate knob by ear, this one added rhythmic control: you can tap the tempo of the sweep, or let it ramp between speeds in the manner of a Leslie speaker speeding up and slowing down.

A six-stage OTA phaser with Tap and Ramp modes

The pedal's control scheme is split into two modes: Tap mode and Ramp mode¹. In Tap mode, the phase rate can be set either by tapping a tempo or by turning the speed knob, so you can dial in a sweep by feel or lock it to the tempo of a song¹. Ramp mode is the Leslie-style behavior: rather than jumping between speeds, the sweep ramps from one to the other, the way a rotating speaker's motor takes time to spin up and down¹.

The six-stage OTA circuit is the heart of the sound. OTA stands for operational transconductance amplifier, the component type used for each phase-shifting stage. Robert Keeley's announcement was direct about why that matters¹:

More stages generally mean more notches in the frequency sweep and a more pronounced, complex phasing effect, which is why stage count is one of the first things players compare between phasers. The same OTA approach appears elsewhere in the pedal world: the Subdecay Quasar DLX Deluxe Phaser is an analog four-stage OTA-based phaser², and CKK Electronic's Robot Phaser was another maker's take on the OTA-based phaser design.

The controls

The published announcement gives the control layout at a high level rather than knob by knob:

For a sense of how Keeley approached phaser controls more generally, the later Keeley Cosmic Country Phaser spelled out its four knobs in detail: Depth for how dramatic the EQ peaks and valleys are as they sweep, Rate for the speed of the low-frequency oscillation, Feedback for feeding a later phasing stage's output back into an earlier one for a slightly resonant, vocal sound, and Level for output volume³.

Power and warranty

The Keeley Phaser runs on a 9-volt battery or a standard negative tip adapter, so it fits a typical pedalboard power supply without special requirements¹. It was announced as backed by Keeley's 5 year warranty¹.

Where it sits in Keeley's phaser line

The Keeley Phaser was the company's original take on the effect, but not its last. In December 2020, Keeley partnered with Daniel Donato on the Cosmic Country Phaser, its first Artist Series pedal, offering two, four or six stages of phasing in three operating modes³. Then in October 2025 came the Oaxa Dual True Stereo Phaser, a dual-engine design in the same enclosure as Keeley's Halo Core, Rotary and Zoma pedals, running two independent phasers simultaneously, each with its own LFO, with true stereo operation in series or parallel⁴. The Oaxa's stage options were reported differently by different outlets: Guitar Pedal X listed secondary functions selecting 2-stage and 6-stage voicings⁴, while Delicious Audio described a single switch selecting 10-stage, 4-stage and uni-vibe voices⁵, and Premier Guitar reported 6-stage, 4-stage or 2-stage phasing⁶⁴.

Compared with those later pedals, the original Keeley Phaser is the straightforward proposition: one analog six-stage OTA circuit, tap tempo, and Leslie-style ramping, in a single box¹.

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