The Keeley MkIII Driver is an overdrive pedal from Keeley that merges a three-control blues driver circuit with two switches for the voicing of its Drive and Tone characteristics. Delicious Audio describes it as drawing on decades of Keeley mod experience with the classic blues driver platform, and it was briefly known as the Muse Driver before taking its current name1. It sits in the same family as other Keeley drives such as the Keeley Katana Blues Drive and the Keeley Super AT MOD.
Circuit and sound
The core is a blues driver circuit, the platform Keeley has modified for years, and the pedal uses JFET transistors, germanium diodes and op-amp gain for what Delicious Audio calls harmonically rich overdrive1. The germanium clipping is the distinguishing feature: when the Drive toggle is engaged, it incorporates two germanium diodes, delivering a smoother, slightly compressed drive1. A second clipping option, Andy's clipping style, enhances brightness and articulation in the attack1.
The name MkIII connects to Keeley's earlier germanium work. In 2017, Robert Keeley, founder and chief engineer of Keeley Electronics, unveiled the Tesla MKIII Fuzz, which Premier Guitar described as a vintage voiced MKIII Soviet Germanium fuzz, with design modifications that Keeley said solved temperature problems that can affect vintage fuzz units2.
Controls
| Control | What it does |
|---|---|
| Drive toggle | Engages two germanium diodes for a smoother, slightly compressed drive1 |
| Clipping option | Andy's clipping style enhances brightness and articulation in the attack1 |
| AT/RK Tone switch | AT position: Andy's preferred voicing with clear and articulate low-end response; RK position: cutting lows for clarity or boosting low-end for power1 |
Bypass and power
The MkIII features a precise buffer for noise-free switching, and it seamlessly transitions between true-bypass and buffered bypass at any moment, so you can choose per setup rather than per pedal purchase1. Power runs from 9 to 18 volts, which Delicious Audio ties to a vast dynamic range and headroom; at 18V the pedal has more headroom than a standard 9V supply provides1.
Questions
Is the Keeley MkIII Driver true bypass or buffered?
Both. Delicious Audio's product page describes it as an overdrive that seamlessly transitions between true-bypass and buffered bypass at any moment, with a precise buffer for noise-free switching. That means you can leave it in buffered mode on a large board to protect your signal, or switch to true bypass if you prefer the pedal out of the chain entirely when it is off.
What voltage can the Keeley MkIII Driver run on?
The MkIII Driver operates on 9 to 18 volts. Delicious Audio notes that the wider voltage range is there for a vast dynamic range and headroom, so running it at 18V gives the circuit more room before it compresses, while 9V lets it share a standard pedalboard supply with the rest of your pedals.
What was the Keeley MkIII Driver called before?
It was briefly known as the Muse Driver before Keeley settled on the MkIII Driver name, according to Delicious Audio's product page. The pedal itself is unchanged in the description: the same blues driver circuit with germanium clipping and the AT and RK voicing switches.
What does the AT position do?
AT stands for Andy Timmons, the guitarist who collaborated on the pedal's design. The AT position of the Tone switch is his preferred voicing, described as having a clear and articulate low-end response. The other position, RK, cuts lows for clarity or boosts the low end for power.
What clipping diodes does the MkIII Driver use?
When the Drive toggle is engaged, the pedal incorporates two germanium diodes, which Delicious Audio says delivers a smoother, slightly compressed drive. There is also a second clipping option in Andy's clipping style, which enhances brightness and articulation in the attack.
Sources (2)
- Keeley MkIII Driver, Delicious Audio, 2024-08-21
- Keeley Launches Tesla MKIII Germanium Fuzz Pedal, Premier Guitar, 2017-06-23
