Phaser Pedals and the Psychedelic Revival

Here is the thing nobody wants to admit about the psychedelic revival: it did not happen because guitarists rediscovered acid, or vinyl, or some lost mystical wisdom about consciousness and sound. It happened because a handful of young players discovered the phaser pedal — specifically, two analog circuits that were already fifty years old when they found them — and realized those circuits were doing something that no amount of digital processing could replicate. The swirling, three-dimensional sweep of a four-stage OTA phaser running slow through a clean amp is one of the most immediately evocative sounds in all of electric guitar. It does not sound vintage. It sounds like the inside of a different universe.

The irony is that psychedelia has never really left. It went underground in the '80s when chorus and digital reverb took over, retreated into shoegaze and post-rock in the '90s, and re-emerged as a legitimate commercial force in the 2010s when Tame Impala and King Gizzard and the Lizard Wizard started pulling massive festival crowds with music that owed more to Syd Barrett than to anything on a contemporary alternative radio playlist. What fueled the revival aesthetically — more than any cultural nostalgia, more than any broader retro trend — was the phaser. Specifically, the analog phaser. And specifically, the two pedals that defined it from the beginning.

What a Phaser Actually Does

Understanding why the phaser is so central to psychedelic sound requires understanding what it actually does to an audio signal, because “swooshing” does not get the job done as a description. At the heart of a phase shifter is a circuit that splits the incoming signal in two and reverses the phase of one strand. A low-frequency oscillator is then applied to both signals, causing them to intersect at varying points along the frequency spectrum. As the oscillator sweeps those notches up and down the audio spectrum, it produces the characteristic swooshing effect that these pedals are famous for.

The result is not just a tremolo or a wobble. It is a moving comb filter — a series of peaks and nulls that travel slowly through your frequency range, making the guitar sound simultaneously present and distant, as if it is moving through three-dimensional space. Set slow, a phaser makes chords breathe. Set medium, it gives single notes a sense of organic motion that no static tone can produce. The effect triggers something in the ear that reads as “other,” as alien, as just slightly removed from physical reality. That quality is precisely what psychedelic music has always been reaching for. The phaser delivers it reliably, with one knob, every time you engage it.

The number of phasing stages matters enormously. A two-stage phaser produces one moving notch and sounds subtle — the MXR Phase 45 operates this way. Four stages produce two notches, which is where you get the deeper, more complex sweep that defines the Phase 90 and the Small Stone. Six stages go further still, producing a lusher, more enveloping effect with three simultaneous notches. The sonic difference between two and four stages is substantial enough that players who know what they want can hear it instantly.

The Orange Box That Started Everything: MXR Phase 90

The MXR Phase 90 was invented by engineer Keith Barr as the inaugural product of MXR Innovations, Inc., which was co-founded by Barr and Terry Sherwood in 1972 in Rochester, New York. The company emerged from the founders' audio repair shop, where they had identified a market gap: most commercial effects pedals were unreliable, bulky, and noisy. The Phase 90 — released in 1974 — was their answer to all three problems simultaneously. MXR's contribution to phase-shift effects was the high-quality, small size, and reliability of the stompbox, in sharp contrast with previous models that tended to be dodgy, bulky, and noisy.

The original version came in a bright orange die-cast aluminum enclosure with a cursive script MXR logo and a single knob for speed. That was it. No depth control, no feedback, no multiple modes — just rate and the circuit itself, priced at approximately $30 to $40 at launch. The “90” in the name references the 90-degree phase shift in its four-stage phasing circuit. Initially hand-built in small batches at their facility in Rochester, these early Script Logo units would become the most coveted version of the pedal — something no one at MXR could have predicted in 1974, because the demand was for any phaser that worked, not for a specific vintage character.

By 1977, MXR changed to a block-style logo, and subtle circuit differences between the Script and Block versions became the subject of audiophile debate that has never fully settled. The Block version is generally described as having a more pronounced midrange and sweep; the Script version as warmer and smoother. MXR went bankrupt in 1984, and Jim Dunlop later bought the brand and resumed production, adding an LED indicator and a DC power jack that the original lacked. Dunlop now offers several variants, including the standard M101 Phase 90 (Reverb) and the EVH signature model, which includes a switch to toggle between Script and Block voicings.

Eddie Van Halen famously used the Phase 90 on the first Van Halen album, cementing its legendary status in rock history. Set at a low speed it is especially effective with rhythmic chords or arpeggios, delivering a shifting, wave-motion sound that is immediately evocative of psychedelic tones — which is why you can hear something like it on almost any Pink Floyd record from the mid-'70s. David Gilmour used an MXR Phase 90 in 1974–75, most notably for the recording of “Shine On You Crazy Diamond” and “Have a Cigar.” The specific application — Colorsound Power Boost into the Phase 90, playing the bridge pickup — is one of the most studied tones in all of classic rock.

The Rival: Electro-Harmonix Small Stone

While MXR was building Phase 90s in Rochester, Electro-Harmonix was developing a direct rival in New York. The origin of the Small Stone dates back to 1974, when EHX president Mike Matthews hired former EMS engineer David Cockerell, whose first design for EH was the Small Stone phaser. The design was based on Cockerell's previous work on the EMS Synthi Hi-Fli from 1971 — and it used a fundamentally different circuit topology than the Phase 90. Rather than field-effect transistors, the Small Stone used Operational Transconductance Amplifiers, which give the pedal its own unique sonic fingerprint.

The Small Stone Phaser, created in 1974, has a unique sound that differs from other phasers thanks to EHX's use of Operational Transconductance Amplifiers, which adds a flavorful distinction from the Phase 90. The OTA-based phaser produces a stronger third harmonic distortion character, giving it a warmer, slightly more organic quality than the FET-based Phase 90. The Small Stone also has a “Color” switch that engages an additional feedback stage, taking the effect from subtle to dramatically pronounced — effectively giving you two different pedals in one enclosure. Electro-Harmonix scored a major success with the Small Stone, and it ended up outselling even the Big Muff Pi during the company's peak years.

The Small Stone went through numerous versions over its history, all OTA-based, but with variations in component values that affect the sound. The current Small Stone Nano (Reverb) maintains the core OTA circuit in a smaller enclosure. Vintage units, particularly the early '70s versions, are sought after by tone chasers willing to pay considerably more for the specific character of the original CA3094 OTA chips. That specificity — a particular vintage of a particular integrated circuit inside a particular revision of a 50-year-old pedal — is exactly the kind of obsession the psychedelic revival has generated.

Kevin Parker and the Small Stone Manifesto

If one person is responsible for putting the phaser back at the center of contemporary guitar culture, it is Kevin Parker of Tame Impala. Parker has been described as one of the primary forces behind the psychedelic renaissance of the past decade — a multi-instrumentalist whose unique ability to meld vintage tone and vanguard production has made him one of the most influential guitar figures of his generation. His approach to the pedalboard is as eclectic as his music, ranging from boutique staples like Empress to old-school legends like Ace Tone.

The phaser is central to his palette. Kevin Parker's phaser pedal of choice is the Electro-Harmonix Small Stone — specifically, a vintage version from the '90s (the Small Stone V4). His pedalboard around the time of Lonerism(2012) included a classic Boss Chorus, a Diamond Vibrato, a Small Stone Phaser, and a Moogerfooger — a modulation section that would define the neo-psychedelic guitar sound for the better part of a decade. Parker's unconventional pedal positioning is also worth noting: he sometimes placed a Blues Driver after a reverb and a phaser, routing signal in ways that violate standard pedalboard logic but produce textures that conventional chains cannot.

The result is audible across the Tame Impala catalog. The phaser appears on “Solitude Is Bliss,” “Endors Toi,” “It Is Not Meant to Be,” “Alter Ego,” and “Sundown Syndrome,” among others — not as a special effect deployed for a single moment, but as a persistent atmospheric texture that defines the entire sonic environment. On InnerSpeaker, the electric guitar tracks have a phaser on them starting at the very beginning. This is not a phaser as accent. It is a phaser as identity. Parker understood that the Small Stone, running slow, transforms a guitar from a physical string instrument into something that sounds genuinely spatial — something that exists in three dimensions rather than two.

King Gizzard and the Psych-Metal Dimension

Tame Impala made the phaser pop-accessible. King Gizzard and the Lizard Wizard made it dangerous. Formed in Melbourne in 2010, the group comprises Stu Mackenzie, Ambrose Kenny-Smith, Cook Craig, Joey Walker, Lucas Harwood, and Michael Cavanagh — a band whose expansive catalog navigates through progressive rock, psychedelic rock, garage rock, thrash metal, and jazz rock, among others. Their sound is often driven by fuzz-laden guitars and microtonal melodies. They have spread their adventures over more than two dozen LPs — five of them released in 2022 alone — which means the phaser and modulation effects in their music are not a style choice so much as a structural necessity.

When you are making records that move between heavy psych and garage thrash and microtonal Turkish psychedelia in the span of a single album, you need effects that can travel between registers without sounding ridiculous in any of them. The phaser can do this because its character is defined by its rate, not by its genre context. Run slow, it sounds like Pink Floyd. Run medium, it sounds like Hendrix. Run fast into a fuzz, it sounds like something from a science fiction score. King Gizzard exploits this range constantly, and their use of phaser and modulation helps give their music its uncanny sense of being simultaneously rooted in classic rock tradition and located somewhere completely alien.

The broader psych revival that Tame Impala and King Gizzard helped anchor also includes bands like Allah-Las, whose 2012 debut was described as a staple in surf-rock and '60s revival, and Thee Oh Sees — now known as Osees — whose live intensity is matched by an equally intense commitment to modulation-heavy guitar tones. The 2010s were, by almost any measure, the richest decade for psychedelic rock since the '70s, and at the center of that richness was the swirling, sweeping, fifty-year-old phaser circuit.

The Boutique Response: EQD, Walrus, and the Modern Phaser Market

The psychedelic revival did not just send players back to vintage Small Stones and script-logo Phase 90s. It also generated demand for boutique phaser pedals that could do more than a single rate knob allowed. The boutique market responded with a generation of phaser pedals that kept the analog OTA topology but added the controls that players increasingly wanted: resonance, blend, vibrato mode, multiple stage counts, and tap tempo.

EarthQuaker Devices' Grand Orbiter is one of the most significant of these. It is a four-stage OTA-based phaser that can go from stationary and resonant to slow and mellow and on through fast and swirly — a range that covers virtually every phaser application you can imagine. The Grand Orbiter has a three-way toggle to select between ranges of modulation, a Rate control for fine-tuning within those ranges, Depth, Sweep, and Resonance controls, and a Phase/Vibrato mode that cuts the dry signal entirely for a true pitch-wobble effect. The Grand Orbiter V3 (Reverb) is handbuilt in Akron, Ohio — exactly the kind of provenance that matters to the market segment that the psychedelic revival created.

Walrus Audio's Lillian Phaser operates on similar principles, offering four-or-six stage switching alongside controls for Rate, Width, Feedback, and a Blend knob that can sweep between dry signal, phased signal, and pure vibrato. The ability to choose between four and six phasing stages in a single pedal is a significant feature — it means the Lillian can genuinely approximate both the Phase 90 character and a lusher, more enveloping six-stage sound. These boutique options represent the market acknowledging that the vintage pedals are increasingly expensive, increasingly hard to find in reliable condition, and not always the best solution for players who need more control.

The Counterargument: Is the Phaser Actually Overused?

Let's be honest about the other side of this. The psychedelic revival has also produced a generation of guitarists who use the phaser as a shortcut — a way to make indifferent playing sound interesting, a way to paper over weak songwriting with hypnotic texture. The phaser is, by its nature, a seductive effect. It makes almost anything sound better on first listen. This is not a feature; it is a trap. A phaser running constantly does not sound psychedelic after ninety seconds. It sounds like wallpaper.

Gilmour understood this. He used the Phase 90 on specific songs, for specific moments, as a deliberate compositional choice. Parker understands it too, even though he uses phasing more aggressively — because on Tame Impala records, the phaser is part of the production architecture, not a substitute for it. The difference between those two approaches and what you hear from second-tier psych-revival bands is the difference between a tool used with intention and a safety blanket. The phaser does not make music psychedelic. It amplifies psychedelia that is already there. If the psychedelia is not there, no amount of slow-rate swooshing will create it.

There is also the question of whether the “psychedelic revival” label is even accurate, or whether it flattens something more complex into a convenient marketing category. The bands most associated with it — Tame Impala, King Gizzard, Allah-Las, Osees — are doing genuinely different things under the same umbrella. What they share is a commitment to modulation-heavy analog texture and a rejection of the digital production aesthetic that dominated the '00s. The phaser is central to that rejection, but it is a means, not an end.

Why Analog Still Wins

Digital phasers have existed since the 1980s, and they have gotten genuinely good. Sophisticated multi-effect units can model the Phase 90 and Small Stone with high accuracy. So why do players who care about psychedelic guitar consistently reach for the analog originals — or for boutique analog alternatives — rather than digital recreations? The answer is partly philosophical and partly sonic, and the two are harder to separate than either camp typically acknowledges.

The philosophical argument goes like this: digital phasers model the output of an analog circuit but do not replicate the behavior of the underlying components. An OTA-based analog phaser responds to the dynamics of your playing in ways that a digital model of that phaser's output cannot, because the dynamics are embedded in the circuit behavior, not in the measured waveform the circuit produces. Whether this distinction is audible in a mix is debatable. Whether it is audible when you are standing in front of an amp with your hands on the strings is much less debatable. Players consistently report that analog phasers feel different to play through — more responsive, more alive, more connected.

The sonic argument is easier to quantify. Many guitarists still prefer the warm, analog sound of vintage phaser models to digital alternatives — a preference that has only grown as the boutique analog market has matured. The resurgence of vintage gear and the rise of boutique pedal manufacturers brought a renewed interest in analog phasers from the 1990s onward, and that trend has only accelerated. The psychedelic revival did not create this preference; it amplified it, gave it cultural currency, and introduced a new generation of players to circuits that had been sitting on vintage pedal shelves for decades, waiting to be rediscovered.

The phaser is fifty years old. The circuits that define it — Keith Barr's FET-based Phase 90, David Cockerell's OTA-based Small Stone — were designed in 1974 by engineers who were solving practical problems, not trying to build psychedelic instruments. What they built turned out to be both. The psychedelic revival of the 2010s and '20s is the third or fourth time these circuits have defined the sound of a genre, and there is no particular reason to think it will be the last.

If you are building a pedalboard for this kind of music, the decision tree is not complicated. Start with the Small Stone if you want warmth, complexity, and a slightly more textured response. Start with the Phase 90 if you want that specific mid-forward sweep that cuts through a dense arrangement without drowning it. Add a boutique option like the Grand Orbiter if you need the flexibility of multiple stages and vibrato mode. Then set the rate slow, turn your amp up, and remember that the phaser is not the music. It is just the most beautiful way to let the music breathe.