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.
Ratings
Pros:
Fantastic, amp-like overdrive. Superior output when changing guitar’s volume.
Cons:
Might be a lot hotter than most other pedals on your board.
Tones:
Ease of Use:
Build/Design:
Value:
Street:
$175
Wren and Cuff, Mercy Phuk
wrenandcuff.com
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.
This month’s mod Dan’s uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel.
Don’t let the name fool you, this is a purely passive device—nothing is going to be boosted. In general, you can’t increase anything with passive electronics that isn’t already there. Period. But you can reshape the tone by deemphasizing certain frequencies and making others more prominent (so … “boost” in guitar marketing language). Removing highs makes lows more apparent, and vice versa. In addition, the use of inductors (which create the magnetic field in a guitar circuit) and capacitors will create resonant peaks and valleys (bandpasses and notches), further coloring the overall tone. This type of bandpass filter only allows certain frequencies to pass through, while others are blocked, and it all works at unity gain.
“You can’t increase anything with passive electronics that isn’t already there … but you can reshape the tone by deemphasizing certain frequencies and making others more prominent.”
All the systems I mentioned above are doing more or less the same thing, using different approaches and slightly different component values. They are all meant to be updated tone controls. Our common tone circuit is usually a variable low-pass filter (aka treble-cut filter), which only allows the low frequencies to pass through, while the high frequencies get sent to ground via the tone cap. Most of these systems are LCR networks, which means that there is not only a capacitor (C), like on our standard tone controls, but also an inductor (L) and a resistor (R).
In general, all these systems are meant to control the midrange in order to scoop the mids, creating a mid-cut. This can be a cool sounding option, e.g. on a Strat for that mid-scooped neck and middle tone.
Dan Torres offered his “midrange kit” via an internet shop that is no longer online, same with his business website. The Torres design is a typical LCR network and looks like the illustration at the top of this column.
Dan’s design uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel. Let’s break down the parts piece by piece:
Any 500k linear pot will do the trick, in one of the rare scenarios where a linear pot works better in a passive guitar system than an audio pot.
(C) 0.039µF cap: This is kind of an odd value. Keeping production tolerances of up to 20 percent in mind, any value that is close will do, so you can use any small cap you want for this. I would prefer a small metallized film cap, and any voltage rating will do. If you want to stay as close as possible to the original design, use any 0.039 µF low-tolerance film cap.
(L) 1.5H inductor: The original design uses a Xicon 42TL021 inductor, which is easy to find and fairly priced. This one is also used in the Bill Lawrence Q-Filter design, the Gibson standard Varitone, and many other systems like this. It’s very small, so it will fit in virtually every electronic compartment of a guitar. It has a frequency range of 300 Hz up to 3.4 kHz, with a primary impedance of 4k ohms (that’s the one we want to use) and a secondary impedance of 600 ohms. Snip off the three secondary leads and the center tap of the primary side and use the two remaining outer primary leads; the primary side is marked with a “P.” On the pic, you can see the two leads you need marked in red, all other leads can be snipped off. You can connect the two remaining leads to the pot either way; it doesn’t matter which of them is going to ground when using it this way.
Drawing courtesy of singlecoil.com
(R) 220k: use a small axial metal film resistor (0.25 W), which is easy to find and is the quasi-standard.
Other designs use slightly different part values—the Bill Lawrence Q-filter has a 1.8H L, 0.02 µF C and 8k R, while the old RA Gresco Tone Qube from the ’80s has a 1.5H L, 0.0033 µF C, and a 180k R, so this is a wide field for experimentation to tweak it for your personal tone.
This mid-cut system can be put into any electric guitar not only as a master tone, but also together with a regular tone control or something like the Fender Greasebucket, or it can be assigned only to a certain pickup. It can be a great way to enhance your sonic palette, so give it a try.
That’s it! Next month, we’ll take a deeper look into how to fight feedback on a Telecaster. It’s a common issue, so stay tuned!
Until then ... keep on modding!