There is a particular kind of magic that happens when a guitar tone begins to breathe — when it pulses and shimmers with a living, rotating quality that feels almost organic. That magic has a name: phase shifting. And in the world of modern rock and metal guitarists, few names carry as much weight alongside that effect as Wylde Audio. The MXR Wylde Audio WA90 Phase Shifter is not merely another pedal on a pedalboard; it is a declaration of identity, a 20th anniversary monument to one of rock guitar’s most enduring and authentic collaborations, and a serious piece of tone-shaping equipment for anyone who demands both dimension and raw aggression from their rig. Built through the celebrated partnership between Dunlop Manufacturing and the legendary guitarist Zakk Wylde — the man behind the volcanic tone of Black Label Society and decades of Ozzy Osbourne’s most blistering guitar work — the WA90 encapsulates a career’s worth of sonic philosophy into a single, sturdy, deceptively simple enclosure. It is a pedal that asks one question — how fast do you want it to swirl? — and then answers with conviction, warmth, and the unmistakable character of analog craftsmanship.
Five of the Most Popular Phase Shifter Pedals on the Market
Before diving deep into the WA90 itself, it is worth setting the scene by surveying the landscape of phase shifters that guitarists consistently reach for today. Phase pedals carry a rich and varied history, and the best-regarded ones each bring something genuinely distinct to the table.
1. MXR Wylde Audio WA90 20th Anniversary Phase Shifter
The centerpiece of this guide, the WA90 is Wylde Audio’s signature analog phase shifter celebrating two decades of creative synergy between Zakk Wylde and Dunlop. It brings the lush, swirling dimension of a classic four-stage phaser to a robust, tour-ready orange enclosure adorned with bold Wylde Audio graphics. A single Rate knob governs everything from slow, hypnotic sweeps to fast, hammering modulation, making it both immediately accessible and genuinely expressive. Stereo output capability expands the pedal’s sonic reach further, delivering an immersive, room-filling quality when run into two amplifiers.
⭐ Rating: 5/5
💲 Price Range: $125.99
2. MXR Phase 90 (M101)
The grandfather of modern phase shifting, the MXR Phase 90 has appeared on countless landmark recordings since the 1970s. Its single-knob simplicity and unmistakable warm, organic sweep have made it the benchmark against which virtually all other phasers are measured. From Eddie Van Halen’s legendary “Eruption” to decades of indie and classic rock recordings, the Phase 90’s four-stage sweep remains one of the most universally beloved effects tones in guitar history. The WA90 owes much of its fundamental sonic DNA directly to this icon.
⭐ Rating: 4.7/5
💲 Price Range: $69.99–$79.99
3. MXR EVH Phase 90 (EVH90)
Another signature extension of the Phase 90 platform, the EVH Phase 90 honors Eddie Van Halen’s iconic use of the original script-logo Phase 90. It adds a Script/Block switch, allowing players to toggle between the warmer, more vintage script-logo voicing and the brighter, more present block-logo sound. This dual-voicing versatility, combined with its association with one of history’s most influential guitarists, makes it a compelling choice for players who want a touch of Van Halen’s shimmering shimmer woven into their tone architecture.
⭐ Rating: 4.8/5
💲 Price Range: $99.99–$109.99
4. Boss PH-3 Phase Shifter
Boss has long been synonymous with reliability and range, and the PH-3 lives up to that reputation fully. Unlike the four-stage design at the heart of MXR’s offerings, the PH-3 features selectable four-, eight-, and ten-stage phasing, plus a unique Rise/Fall mode and a step-phaser function that can produce distinctly choppy, rhythmic movement. It is a digital pedal that excels at covering broad sonic territory, from gentle classic swirls to extreme, almost pitch-shifting modulation. For the experimentally inclined guitarist, the PH-3 is hard to beat.
⭐ Rating: 4.5/5
💲 Price Range: $99.99–$119.99
5. Electro-Harmonix Small Stone
An absolute classic of New York-born effects design, the Electro-Harmonix Small Stone delivers a warm, thick, slightly syrupy phase character that has always distinguished it from MXR’s tighter, more precise sweep. It has been used by everyone from David Gilmour to Radiohead, demonstrating cross-genre appeal of the highest order. The Color switch adds a secondary tonal dimension, making the sweep either more transparent or distinctly saturated. It remains one of the most beloved and character-rich phase options available at its price point.
⭐ Rating: 4.6/5
💲 Price Range: $79.99–$99.99
The Story Behind the WA90: Twenty Years of Tone
To truly appreciate the MXR Wylde Audio WA90, you need to understand what it commemorates and why that heritage matters. Dunlop Manufacturing and Zakk Wylde have maintained one of the most enduring and genuinely authentic artist partnerships in the guitar accessories industry. Over two decades, this collaboration has produced signature picks, strings, wah pedals, and effects units, all bearing Zakk’s unmistakable aesthetic and driven by his practical, no-nonsense approach to live and studio performance. This is not a marketing arrangement — it is a working relationship built on shared respect for tone, craftsmanship, and the demands of real-world performance at the highest level.
Zakk Wylde is not a guitarist who hides behind complexity. His sound — massive, muscular, and unmistakably alive — is built on a foundation of classic tools wielded with absolute conviction. When he reaches for a phase effect, he is not looking for something esoteric or endlessly programmable. He wants something that responds to his playing, that adds living, breathing movement to his tone without complicating his workflow or demanding his attention mid-set. That philosophy, deeply personal and hard-won through decades of touring, is the soul of the WA90.
The pedal wears its anniversary status with quiet pride. The bold orange enclosure, emblazoned with Wylde Audio’s distinctive graphics, is visually commanding on any pedalboard. It announces itself as something beyond the standard-issue black box, something with a story and a lineage. It is a collector’s piece as much as a working tool, and that duality makes it all the more compelling for the guitarist who cares both about how their gear performs and what it says about who they are as a player.
Analog at Heart: Why the WA90’s Circuit Matters
In an era where digital effects can replicate virtually any analog circuit with increasing precision and at lower cost, the WA90’s all-analog design is a deliberate and meaningful choice. Analog phase shifting works by passing the guitar signal through a series of all-pass filter stages. Each stage imparts a phase shift at specific frequencies, and when this phase-shifted signal is blended back with the dry signal, certain frequencies cancel each other out while others reinforce — producing the characteristic sweeping notch-filter effect that defines the phaser sound.
The WA90 employs a four-stage analog phase circuit, placing it in the same fundamental lineage as the original MXR Phase 90 and every great phase shifter in that tradition. A four-stage design produces a sound that is wide, musical, and eminently playable — warm enough to feel organic and living, articulate enough to cut through a dense mix when the Rate is pushed. It is the Goldilocks configuration of phase circuits: not so subtle that it disappears into the background, not so extreme that it overwhelms the fundamental character of the guitar.
What this means in practice is that the WA90 responds to the nuances of your playing in a way that digital approximations, however sophisticated, often struggle to replicate convincingly. The interaction between your guitar’s output, your playing dynamics, and an analog phase circuit has a subtle, almost visceral liveliness — a gentle compression and bloom that makes the effect feel as though it is breathing with you rather than executing a programmed function independently of your input.
The Rate Knob: Simple Does Not Mean Limited
One of the most striking things about the WA90 — particularly for players accustomed to multi-parameter pedals bristling with knobs, switches, and secondary functions — is its singular focus: one Rate knob. This is emphatically not a limitation. It is an intentional and informed design philosophy, one that Zakk Wylde has championed consistently throughout his career and one that the greatest pedal designers in history have returned to again and again.
The Rate knob’s range is impressively broad and musically well-calibrated. At its lowest settings, the phase sweep is glacially slow — an almost oceanic rise and fall that adds a sense of enormous, dreamlike depth to clean or lightly overdriven chord voicings. The effect at this setting is almost subliminal, something listeners feel more than consciously identify, a sense that the guitar is larger and more dimensional than it has any right to be coming out of a single amplifier.
Roll the Rate control up through the midpoint and you arrive in territory that is immediately recognizable — lush, warm, classic, the sound of rock history from the 1970s through the present. This is where many players will spend the majority of their time with the WA90, dialing in a sweep speed that complements the tempo of the music and locks into the groove with satisfying authority. Push the Rate knob further still and the WA90 transforms decisively, driving into a fast, aggressive, hammering phase effect that suits Zakk’s trademark power-riffing style with complete authority and zero hesitation.
The absence of additional parameters is, in many ways, not a concession but a gift. It forces the player to respond to the music and trust their ears rather than second-guessing settings or endlessly tweaking secondary controls. There is something deeply and genuinely musical about a pedal that presents one variable, asks you to make a decision, and then delivers the result with full commitment.
Stereo Modulation: Expanding the Soundscape
While the WA90 performs beautifully in a standard mono configuration — as confirmed by players who describe rich, full tones even running into a single amplifier — the pedal opens up into something truly spectacular when used in a stereo setup. Stereo modulation splits the phase effect across two amplifiers, creating a wide, immersive soundstage where the sweep feels as though it is physically moving through the room around the audience.
For players running a wet/dry rig or a stereo two-amp setup, the WA90 delivers a spatial depth that is immediately striking, the kind of effect that turns heads in a room even before you have finished playing the first chord. The phase sweep takes on a genuinely three-dimensional quality, with the notches and peaks of the filter appearing to shift between your left and right amplifiers in a way that is apparent even to listeners with no technical knowledge of what they are hearing. They simply know it sounds enormous, alive, and authoritative.
This stereo capability is a significant feature at the WA90’s price point and speaks directly to the pedal’s versatility and its fitness for professional use. Whether you are a bedroom player running a single practice combo or a touring guitarist with a full stereo rig covering large stages, the WA90 meets you where you are without compromise.
Build Quality: Made to Survive the Road
Zakk Wylde is not a studio-only artist. He is a road warrior, a performer who has spent decades delivering physically and emotionally demanding live performances night after night across the globe. Any piece of gear bearing his name must be capable of enduring that same level of relentless punishment, and the WA90 is engineered accordingly.
The pedal’s heavy-duty die-cast aluminum enclosure is the same robust construction standard that MXR has applied to its professional pedal line for decades — a standard refined through years of feedback from touring musicians who cannot afford a pedal failure in the middle of a performance. The hardware is solid throughout, the knob responds with pleasing precision, and the overall finish shows no signs of cutting corners. This is a pedal you can trust on a dark stage under the pressure of a live performance, one that will not introduce the wrong kind of surprise into your show.
True bypass switching ensures that when the WA90 is disengaged, your signal passes through completely uncolored, preserving the full integrity of your base tone. This is a critical feature for players with high-gain rigs where even small amounts of passive signal degradation can cloud the clarity and definition of the dry sound, and it reflects the seriousness with which MXR and Wylde Audio approached every aspect of this pedal’s design.
Who Is the WA90 Built For?
On the surface, the WA90’s association with Zakk Wylde might suggest a pedal built exclusively for hard rock and metal players, and it absolutely excels in those contexts. The pedal’s assertive phase sweep sits beautifully in front of a high-gain amplifier, adding living movement to crushing riffs without muddying the low end or softening the attack of the pick. Players in that world will find the WA90 feels immediately at home, immediately right.
But the WA90’s analog four-stage circuit is fundamentally musical in a way that transcends any single genre. Blues players will find that the gentle, slow settings add an ethereal shimmer to slow-burn bends and long, searching vibrato phrases. Classic rock guitarists will appreciate the warm, vintage-voiced sweep that directly echoes the Phase 90s heard on records from the early 1970s. Psychedelic and shoegaze players seeking maximum swirl will find that the faster settings deliver that hypnotic, spiraling, almost vertiginous quality with all the warmth and harmonic richness that an analog circuit uniquely provides.
The pedal’s elegant simplicity — its principled refusal to overcomplicate — actually makes it more approachable and more genre-flexible than its hard rock pedigree might initially suggest. If you want a phase pedal that sounds magnificent, behaves reliably under pressure, and does not require a manual to operate, the WA90 is a deeply satisfying choice regardless of what music you play.
Value Proposition: Is the WA90 Worth $125.99?
At $125.99, the WA90 occupies the mid-tier of the phase pedal market — meaningfully above budget options but well below the pricing of boutique and custom-shop alternatives. For what it delivers across every relevant dimension, this price point represents genuine and defensible value. You are investing in an all-analog circuit with proven lineage, a true bypass footswitch that respects your base tone, stereo output capability that most competing pedals lack at this price, a heavy-duty touring-grade enclosure built to survive professional use, and the credibility of a signature design that has been worn and endorsed by one of rock’s most formidable and authentic guitarists.
Comparable analog phase pedals from respected manufacturers frequently approach or exceed this price without offering the same combination of build quality, sonic character, stereo capability, and heritage. The WA90’s closest relatives within the MXR family — the Phase 90 and the EVH Phase 90 — are less expensive, but they also lack the stereo output and the specific, broader voicing that makes the WA90 feel slightly more present and full-bodied in a dense mix.
For a gigging guitarist who wants a phase pedal that will last years of hard use, sound authentically and consistently great, and make an impression on and off the stage, the WA90 is money exceptionally well spent.
The Legacy of a Collaboration
It is worth stepping back to appreciate what the 20th anniversary WA90 represents beyond its circuit and its enclosure. Sustained, authentic artist partnerships in the guitar industry are rarer than they might appear from the outside. Equipment companies and artists come together regularly for commercial reasons, but enduring collaborations — ones where the artist genuinely uses and actively shapes the products, where the gear reflects real artistic experience rather than brand strategy — belong to a different and rarer category entirely. The two-decade relationship between Dunlop and Zakk Wylde belongs unambiguously in that second category.
Every piece of gear that emerges from this partnership carries with it the implicit endorsement not of a brand ambassador delivering prepared lines, but of a guitarist who has played these products on the biggest stages in rock and metal for twenty consecutive years. That authenticity is woven into the WA90 in ways that are difficult to quantify through a spec sheet but immediately apparent when you plug in, step on the switch, and let the sweep do its work.
Final Thoughts
The MXR Wylde Audio WA90 Phase Shifter is, at its core, a masterclass in purposeful and confident design. It takes a celebrated analog circuit, voices it with genuine care and experience, houses it in a bomber-proof enclosure built to professional standards, and offers it to the world at a price that respects the working guitarist’s budget and judgment. Its single Rate knob is not a compromise — it is a statement of priorities. Its striking orange finish is not mere vanity — it is an identity worn openly and proudly. And its analog soul is not nostalgia for nostalgia’s sake — it is a commitment to the kind of tone that has moved people for fifty years and will continue to do so for fifty more.
Whether you are stepping onto a stage in front of thousands or tracking guitar quietly in a home studio at midnight, the WA90 will serve you with distinction and consistency. It is the kind of pedal that eventually disappears into your playing — not because it is subtle, but because it becomes so integral to your sound that performing without it feels like playing without a piece of yourself. Wylde Audio’s WA90 is more than a 20th anniversary commemoration of a great collaboration. It is proof, delivered through twelve square inches of orange aluminum and analog circuitry, that the best gear is always born when authentic artistry meets disciplined engineering — and the result, in this case, swirls beautifully.
