The Wren and Cuff Mercy Phuk is a one-knob overdrive for bass and guitar, and the tenth pedal in the company's growing line1. It is built around two gain stages: the signal first meets an op-amp driven MOSFET/LED asymmetrical clipping stage, and past a certain point on the knob a second stage combines germanium diode and LED clipping1. Premier Guitar's reviewer summed it up as a "Fantastic, amp-like overdrive. Superior output when changing guitar's volume."1
The one-knob control layout
The Mercy Phuk's front panel carries a single knob, a side-mounted two-way toggle, and one footswitch1. The knob does more than set level: as it is turned clockwise, the volume increases along with the distortion dynamic, and at around 12 o'clock it engages the second gain stage1. In practice that makes the knob a sweep through the pedal's whole character, from the first clipping stage alone into the harder-clipping germanium and LED stage.
The toggle's function is not described in the published material, so its two positions are best confirmed by ear or by the maker at www.wrenandcuff.com2.
Inside the circuit: MOSFET, LED and germanium clipping
The Mercy Phuk's two stages clip the signal in different ways:
- First gain stage: an op-amp-driven MOSFET/LED asymmetrical clipping section, with an internal trim pot that lets the player fine-tune the amount of drive2
- Second gain stage: another asymmetrical clipping section, a hybrid of germanium diodes and an LED12
Asymmetrical clipping means the two halves of the waveform are clipped differently, an approach both stages here share. The internal trim pot on the first stage is the pedal's hidden fourth control: it sets how much drive the MOSFET/LED section contributes before the knob ever brings in the second stage2.
What reviewers said
Premier Guitar's review came away with the pedal described as a "Fantastic, amp-like overdrive. Superior output when changing guitar's volume."1 The volume-knob cleanup the reviewer highlights is the trait overdrive players most often look for in an amp-like pedal, and it is the specific strength the review names. Vintage Guitar's announcement covers the pedal's intended use for bass and guitar and its internal drive trim2.
Within the maker's range, the Mercy Phuk itself sits at the simple end: Wren and Cuff describes it as having "one knob, one side-mounted, two-way toggle, and one footswitch," a single footswitch controlling the effect3.
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Questions
How many knobs does the Mercy Phuk have?
Just one. The single knob increases the volume along with the distortion dynamic as it is turned clockwise, and at around 12 o'clock it engages the pedal's second gain stage, which combines germanium diode and LED clipping. The pedal also has one side-mounted two-way toggle and one footswitch.
What does the internal trim pot on the Mercy Phuk do?
The internal trim pot lets the player fine-tune the amount of drive in the pedal's first clipping section, the op-amp-driven MOSFET/LED asymmetrical stage. It sits inside the pedal rather than on the top panel, so it is set with a screwdriver rather than adjusted while playing.
Does the Mercy Phuk clean up with the guitar volume?
Premier Guitar's reviewer found it did, describing the pedal as a fantastic, amp-like overdrive with superior output when changing the guitar's volume. That kind of volume-knob response is what players usually mean by amp-like cleanup.
Sources (3)
- Wren and Cuff Mercy Phuk Overdrive Review, Premier Guitar, 2013-08-20
- Wren and Cuff Offers Mercy Phuk OD, Vintage Guitar magazine, 2013-03-07
- Wren And Cuff Two Five Overdrive, Delicious Audio, 2018-05-07
