The Keeley 4 Knob Compressor is a compressor pedal from Keeley Electronics. As the maker puts it, "a compressor pedal decreases dynamic range": it evens out the difference between your quietest and loudest notes, which is why compressors are used to add sustain and smooth out a playing style. The 4 Knob version gives you four controls over that process, and Keeley notes that "there are several useful starting points outlined in the owner's manual" for players who want a place to begin.1
The four controls
Each knob covers one part of how the compression behaves:
| Control | What it does |
|---|---|
| Level | Adjusts the output of the pedal, either at unity so there is no appreciable level change, or as a boost to cut through for soloing or to drive the input of a tube amp harder1 |
| Sustain | Combines threshold, release and ratio, adjusting those factors in combination to result in increased sustain1 |
| Attack | Determines how fast the compressor starts to work once you cross the threshold; faster settings react relatively transparently, while extremely slow settings create an exaggerated effect1 |
| Clipping | Adjusts the input gain of the 4 Knob, letting you increase or reduce the level on input to best match your instrument to the pedal1 |
The Sustain knob is the one that sets how much compression you hear, since it pulls threshold, release and ratio together rather than exposing them separately. Attack is the knob to reach for when the pedal reacts too quickly or too slowly to your picking: a fast setting stays out of the way, and a slow one makes the compression obvious. Clipping works before that stage, matching the incoming signal from whatever guitar or bass you plug in.1
The Arlon Prince custom finish
Alongside the standard version, Keeley has offered a custom-painted edition of the pedal: the Keeley Arlon Prince 4 Knob Compressor, with paint by Arlon Prince of Arloart.com. Keeley described these as a limited edition, announced in a low-profile enclosure.2 The custom finishes were offered across several Keeley pedals, with the maker stating that "Right now they will be available for Luna Overdrives, 4 Knob Compressors, and Katanas."3
The Arlon Prince version is a limited edition, so availability depends on what Keeley has produced.2
Where it sits in Keeley's compressor range
Keeley builds several compressors, and the 4 Knob is the version that exposes the most control on the face of the pedal. The Keeley Compressor Plus and the two-knob Keeley Compressor Mini are simpler alternatives, and the Keeley Aria Compressor and Overdrive Pedal pairs compression with drive. If you want the 4 Knob format with custom artwork, the Arlon Prince edition is the one to look for.12
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Sources (3)
- Manic Compressive, Robert Keeley, 2013-07-23
- New Low Profile Arlon Prince Compressors Now In Stock, Keeley Electronics Guitar Effects Pedals, 2012-05-17
- Killer New Arlon Prince Custom Finishes Now Available, Keeley Electronics Guitar Effects Pedals, 2012-02-22
