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Wren and Cuff Mercy Phuk Overdrive Review

Despite its minimal one-knob design, this innovative overdrive delivers many exciting, amp-like tones.

Wren and Cuff's newest overdrive - the Mercy Phuk.

The boys at Wren and Cuff are hard at work. The Mercy Phuk is the tenth pedal in their growing line, which is impressive given the quality of their output thus far. I’ve had the pleasure of playing their Caprid fuzz [Premier Guitar, August 2012], and the Box of War was a Premier Gear Award winner [October 2012], so I jumped at the chance to get my hands on the Mercy Phuk. Upon opening the box, though, I was stunned to find an overdrive with just one knob! “What the hell,” I thought? “Where’s the EQ? The gain knob?” Well, after plugging it in, any fears about limitations in the Mercy Phuk’s vanished. This overdrive teems with tones.

Many Tones, Not So Many Knobs
The Mercy Phuk is as simple as it gets: one knob, one side-mounted, two-way toggle, and one footswitch. But the Phuk is far from one-dimensional. First, your signal meets up with an op-amp driven MOSFET/LED asymmetrical clipping stage. As you turn the knob clockwise, the volume increases along with the distortion dynamic. At around 12 o’clock, you engage the second gain stage, which combines a germanium diode and LED clipping.

Popping off the back plate reveals a tiny PCB-mounted trimpot for adjusting overall gain. (Wren and Cuff ships the unit with the pot set just under maximum.) The final embellishment is the side-mounted Girth switch. Its ‘up’ position increases low-end content for a heftier growl. The other position provides a more mid-focused attack.


Fantastic, amp-like overdrive. Superior output when changing guitar’s volume.

Might be a lot hotter than most other pedals on your board.


Ease of Use:




Wren and Cuff, Mercy Phuk

Have Mercy!
Despite its minimalist design, the Mercy Phuk does require some tweaking for optimal results. Crank it, and you’ll probably experience permanent hearing loss, so it’s best to be a little conservative going in. Using a Les Paul and a Fender Twin Reverb reissue, I set the knob at 10 o’clock, just tickling the first gain stage. Even here, the volume jump is substantial, so using your guitar’s volume control is essential for getting the best tones from your rig.

With the level knob wide open, the Mercy Phuk’s overdrive is huge, bordering on distortion-like output. Even so, tones have clear foundations. Using the Les Paul’s bridge pickup, I set the level knob to about 50% and got a smooth lead tone akin John Fogerty’s clean-but-dirty leads from “Susie Q.”

Switched to an Orange OR50 amp and setting the Mercy Phuk’s level control around noon, I could hear the pedal’s second gain stage kick in with a heavier attack. This is a sweet spot for big leads and chunky rhythm—Mark Knopfler’s explosive “Money for Nothing” opener, for example, shines through the overdriven Orange in rich, growling detail.

The trimpot is responsive and effective. Lower ranges deliver a fat, slightly dirty boost—a great setting for pushing leads into heavier amp-like saturation. With the girth switch off, this trimpot setting helps you cut through a full band without leaving the boost/overdrive realm. But the single-coils of a Stratocaster and Jaguar benefitted from the fatter girth setting, which smoothed the toppy sound of their bridge pickups.

The Verdict
The Mercy Phuk is not a run-of-the-mill boutique clone, and it won’t suit everyone’s overdrive needs—particularly folks who need a more transparent clean boost. But old-school players will get a kick out of the Phuk’s responsive gain structure, distinct volume boost, and harmonic clarity. Getting the most from the circuit requires playing with your guitar’s volume control, though you can also play wide-open for a seriously scathing overdrive. If that’s the sound you seek, and if you’re keen to break out of the TS-9 template, the $175 won’t seem too steep, especially given Phuk’s build quality.