Darkglass Duality

The Darkglass Duality is a fuzz pedal for bass that puts two separate fuzz circuits in one enclosure: what Darkglass calls "a gated saw-tooth wave and a raunchy high-gain sound," which can be mixed together in any ratio for a wide range of textures¹. The idea is right there in the name. Instead of choosing between a thick, gated, classic-sounding fuzz and a tighter modern high-gain fuzz, one knob, called Duality, pans between the two circuits, with every blend in between available across its rotation²³⁴.

The original version, released in 2013 as the Duality Dual Fuzz Engine, was made by Darkglass Electronics and aimed squarely at bass players⁵⁶. Premier Guitar's reviewer put it plainly: with its low-pass filter and blend control, "the Duality is very clearly built to address the shortcomings bass players encounter when adapting guitar fuzz to their own unique requirements"⁷. The pedal is now sold out at Darkglass, and in late 2022 the company released a more compact successor, the Duality DFZ¹⁸.

What the Duality does: two fuzz circuits in one pedal

The core of the pedal is the pair of fuzz paths. One is the gated saw-tooth circuit, which MusicRadar's reviewers described as "a thick, classic sounding fuzz"¹¹. The other is the high-gain path, which Darkglass describes as tighter⁷. Aion FX, which traced the circuit in 2021, characterized the two paths in more technical terms: the first sounds similar to Darkglass's flagship Microtubes B3K, "an aggressive but articulate and versatile drive tone," while the second is "all-out square wave mayhem, complete with heavily gated 'velcro' tones characteristic of misbiased transistors"¹².

Under the hood, the two paths work quite differently. The first is a cascade of overloaded CD4049UBE hex inverter stages, three CMOS stages in a row, providing the distortion¹². The second uses a single op-amp stage configured as a comparator, with the signal into the inverting input, the non-inverting input tied to a reference voltage, and no feedback path; the comparator is followed by a primitive two-diode noise gate to keep things quiet when no signal is present, and those diodes also add crossover distortion¹². Aion FX notes the comparator concept is similar to Craig Anderton's "Ultra Fuzz," first published in Electronics Project for Musicians in 1978, though the Duality's comparator threshold is fixed rather than variable¹².

On top of the two fuzz paths sits a clean blend, so you can mix fuzz with your untouched bass signal. MusicRadar found the Blend control runs from fully clean at one extreme to full fuzz at the other, with both clean and effected signals audible at once¹¹. Aion FX's trace adds that the combination of the effect volume and the clean blend gives finer control over the mix than the blend knob alone, though it is not as flexible as two fully independent volume controls¹².

Controls

Reviewers found plenty of range in those knobs. Pedal of the Day's Mike B called the Filter's range "broad and sweeping, allowing the player to cover a lot of ground musically with simple and slight variations of this knob's setting placement"⁶, and MusicRadar noted that the Filter increases resonance, top-end clarity and definition, while Level adds grit and distortion¹¹. The pedal also uses soft footswitches that Pedal of the Day found notably quiet underfoot⁶.

Power and connections

The Duality runs on a regulated 9V DC adapter with a center-negative plug only, drawing roughly 40 mA². There is no battery option; as Premier Guitar's reviewer put it, "You can keep those batteries in your kid's toys because the only way to power the Duality is with a 9V adaptor"⁷.

Connections are a standard instrument input and output, with a 1MΩ input impedance and 100kΩ output impedance². The enclosure measures 50 mm wide, 100 mm long and 45 mm high, and weighs 205 g². Bass Musician Magazine listed slightly different figures for its review unit, 11.3 by 7.5 cm, so the two sources disagree on exact dimensions⁴. The bypass is a JFET flip-flop buffered design using the CD4049 chip rather than transistors; in bypass mode the fuzz path is disabled and the blend is hard-wired to 100%¹².

What is under the magnetic bottom lid

The bottom lid of the enclosure is magnetic and comes off to reveal the pedal's internal controls². Darkglass's manual simply instructs, "Open the magnetic bottom lid to access the controls"², so anything beyond the four top-panel knobs lives inside the box. The warranty can be activated by registering the serial number on the back of the pedal at Darkglass's registration site².

Where it came from and how it is built

The Duality Fuzz was announced in December 2013, described in the launch press release as "Designed in Helsinki Finland, built in Seattle USA"¹⁰. Darkglass Electronics is a Finnish company, and reviewers have consistently introduced the Duality as a pedal from Finland⁶. At launch it carried a MAP of $249 in the US and €195 in Europe¹⁰, and Bass Musician Magazine still listed $249 in 2015, placing it firmly in boutique territory⁴.

The enclosure styling mirrors Darkglass's Vintage Microtubes but in a darker hue, with dials Premier Guitar found somewhat cramped but logically arranged⁷. MusicRadar described it as "classily presented in a brushed silver matte finish with a mirror chromed top facing," with smooth-turning controls and a solid stomp button, concluding the whole pedal is "evidently built to last"¹¹. Aion FX's traced unit carried a PCB marked Revision 4-K; a newer Revision 7 board was partially traced on Freestompboxes.org with only one apparent component difference, so the revisions appear to be mostly layout optimizations¹². Revision 7 adds R11, a 1M bias resistor at the input of the op-amp buffer after the CMOS inverters, which Aion FX called an "editorial" change rather than a tonal tweak¹².

Versions: Duality Dual Fuzz Engine and Duality DFZ

The original Duality Dual Fuzz Engine, released in 2013, is the four-knob version described above⁵. In November 2022 Darkglass launched the Duality DFZ, its successor⁸. Like the original, the DFZ packs two discrete fuzz circuits into one enclosure, the same gated saw-tooth wave and raunchy high-gain sound⁹. The differences are in the format and the controls: the DFZ is a compact pedal suited to a mini pedalboard, sharing the same design footprint as Darkglass's Microtubes B1K overdrive⁸⁹. Its controls are significantly streamlined around a central rotary control, with a stacked rotary that tweaks the output and blends between the two fuzz circuits⁸⁹. Guitar World reported it available at launch for £142⁹.

What reviewers said

Published reviews of the original were positive across the board. MusicRadar's verdict: "A real winner from Darkglass, impressively simple to use but very effective. We're impressed!"¹¹. Premier Guitar's review summed up its pros as "Big and versatile fuzz tones in a small box"⁷, and the reviewer tested it with a Nash P-Style bass through an Epifani AL 112 combo, and with a 1964 Fender Jazz bass paired with a Boss OC-2⁷. Bass Musician Magazine's Kilian Duarte rated construction 5 out of 5, calling it "incredibly durable and well put together with a solid chassis," and closed with "The Duality Fuzz Engine pedal is a fun pedal that was a joy to play"⁴.

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