TWA WX-01 Wahxidizer

The TWA WX-01 Wahxidizer is an envelope-controlled fuzz pedal with an octave-up harmonic, a parametric EQ, and a filter that reacts to how hard you play. TWA bills it simply as an Envelope-Controlled Fuzz, and Pedal of the Day calls it an Envelope-Controlled Octave Fuzz Filter Wah, which is a fuller description of what the box actually does: it layers Super Fuzz-style octave fuzz on top of a sweepable filter¹². The fuzz circuit is inspired by the vintage Univox Super Fuzz, and the pedal carries a pronounced upper octave harmonic for Octavia and ring-modulator-style effects¹.

The core idea is the EQ's center frequency, which can be swept three different ways: manually with a knob, by your playing dynamics through the envelope detection circuit, or by an external expression pedal plugged into the EXP jack³². With the envelope circuit engaged, the filter climbs toward the peak of its range in response to your attack, so the pedal behaves like a wah that follows your hands rather than your foot.

What it does: envelope-controlled octave fuzz and filter

The Wahxidizer is not a conventional fuzz. Pedal of the Day's reviewer found that it "isn't just a fuzz pedal," and that the octave-fuzz character of the Univox Super Fuzz has been carried over faithfully: "All of the crazy, crunchy, cacophonous octave-fuzz tones of the Univox have been replicated with pinpoint accuracy"². On top of that fuzz engine sits the parametric EQ section, and it is the EQ that gives the pedal its wah-like behavior, since its center frequency moves in response to your signal.

How the filter moves depends on how you set it up:

• Manual: turn the frequency control yourself for a fixed, scooped or peaked voicing.
• Envelope: switch on the ACCELERANT and the envelope detection circuit sweeps the filter with your playing dynamics⁴.
• Expression: plug into the EXP jack and sweep the EQ frequency with your foot, either with a standard expression pedal or TWA's Side Step⁴¹².

Pedal of the Day's reviewer described the result as a pedal that "punches you right in the face from the moment it's activated," responding "with explosive, touch-sensitive power," with "distorted, vintage, wah-flavored tones" pouring out². TWA's own description leans the same way: "Caustic on Guitar, crushing on Bass, the Wahxidizer™ will turn your tone into a colossal, rusting hulk of expressive, explosive, and corrosive sound"¹.

That verdict matters for bass players in particular: the reviewer found the pedal crushing on bass, and the REDOX POTENTIAL switch, which selects between two overall sensitivity settings for the envelope detection circuit, exists to accommodate both low and high signal levels³². Players considering it for bass might also compare TWA's Krytical Mass, a reactive octave fuzz based on the vintage Maestro Bass Brassmaster.

The controls

TWA gives the controls chemistry-themed names, with the plain function in parentheses. Delicious Audio noted that "the Wahxidizer features controls that are not immediately intuitive," so the table below maps each label to what it does⁵.

Two details stand out for a player comparing this against a straight Super Fuzz clone. First, the Fat/Scoop switch, which on the original Univox was an internal or panel EQ choice, is a footswitch here, so you can jump between two fuzz voicings mid-phrase². Second, the internal LOW/HIGH GAIN mini switch gives you a choice of high or higher gain, so the pedal's floor is already set fairly hot⁴.

History: from the Univox Super Fuzz and Maxon Ether

The Wahxidizer's family tree runs through two pedals. The fuzz circuit is inspired by the vintage Univox Super Fuzz¹. The Super Fuzz was originally developed by the Shin-ei company in Japan in the late 1960s, and saw later incarnations under brands such as Apollo, Shaftesbury, JAX, Tiesco, Memphis, and most famously Univox⁶. Technically it is a six-transistor design, with the Q4 and Q5 stages forming the octave section, and a typical build uses six 2N5088 transistors, two 50K linear pots, and a 10k trimpot for the octave biasing⁷⁸.

The more direct ancestor is the Maxon Fuzz Elements Ether FE10, part of a Fuzz Elements series designed to emulate classic circuits: the Air emulated the Triangle-Knob Big Muff, and the Ether emulated the Super Fuzz, with each adding a parametric EQ circuit¹⁹. TWA's own account of the Wahxidizer's origin is that they "kicked the concept over to our engineer along with an Ether pedal to be Frankenstein'd into our dream device," and that "Once he designed an envelope detection circuit, the rest of the pedal came together fairly easily"³. In other words, the Wahxidizer is a modified Maxon Ether, itself a Super Fuzz emulation with a parametric EQ, with TWA's engineer adding the envelope detection that became the pedal's defining feature³.

The project took years to reach the public. TWA has had a prototype of the Wahxidizer knocking around since 2017, with the release delayed by a 2018 pause and then the pandemic before the pedal finally shipped⁵⁴.

The NAMM prototype edition

Godlyke's site has carried two B-stock listings for one-of-a-kind Wahxidizer prototypes made for NAMM: one with a black screen print on the chassis, and one in a gloss black finish¹⁴. Both are described as production sample prototypes for the WX-01 with the same circuit as the regular Wahxidizer, sold as B-stock in excellent condition with the box included¹⁴. Both listings are now sold out¹⁴.

Both listings show the same regular price for the B-stock unit, £230.00 GBP¹⁴. The production Wahxidizer itself ships in a rust-colored enclosure, as Pedal of the Day's review unit showed².

What reviewers made of it

Pedal of the Day's review is the fullest published assessment. The reviewer found the pedal "punches you right in the face from the moment it's activated," and described "the distorted, vintage, wah-flavored tones just keep pouring out"². TWA itself describes the Wahxidizer as "Caustic on Guitar, crushing on Bass," promising "a colossal, rusting hulk of expressive, explosive, and corrosive sound"². The maker's product page shows 4 reviews, 100% positive³.

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