4ms Phaseur Fleur ()
It hums when you're not even playing - some call it a glitch, others call it alive.
Overview
The 4ms Phaseur Fleur is not a standard phaser pedal. It's an optical-based boutique stompbox. 4ms is the same outfit known for dense, knob-covered noise and drone machines, so a guitar pedal from them is a rare detour from modular synthesis. It's officially discontinued now. If you want one, you're hunting a used unit or building your own from the DIY layouts once shared on the Commonsound/4ms website.
It's packed into a 4″ square box. It's marketed mainly as a phaser, but it's also been labeled a "vibe pedal" and even a "ring modulator pedal" in some corners. Owners report a "smallstone-ish flavor," like the thick, organic swirl of vintage phase shifters, but with a wider, more experimental range. It's capable of "wavering phase shifting, fluttering vibrato," and sounds that sit somewhere between musical and uncanny. It's been praised as "beautiful on guitars" and "absolutely gorgeous with s..." (the quote cuts off there), and it works on guitar, synth, or bass.
This isn't a plug-and-play effect. One builder wrote, "It did take some major tweaking of the trimpots to get some nice phasing." That's part of the design. It's "incredibly tweakable," and you coax the sound out by dialing in the sweet spot where it breathes without screaming.
Specifications
| Manufacturer | 4ms / Commonsound |
| Product Type | Phaser pedal |
| Number of Stages | 6 stage phaser |
| Phase Shift Capability | one thousand eighty degrees of phase shift |
| Power Requirement | standard 9V |
| Enclosure Size | 4″ square box |
| Number of Pots | 5 pots |
| Blend Control Pot Value | B10K pot |
| Other Pots Value | B100K (suggested) |
| Bypass Type | True-bypass circuit with LED indicator |
Key Features
Optical 6-Stage Phaser with Deep Control
The Phaseur Fleur is a 6-stage optical phaser. It uses light-dependent resistors (LDRs) and LEDs to create the sweeping phase effect, rather than voltage-controlled amplifiers or transistors. That gives it a smoother, more organic response, with a natural lag and bloom that many describe as more "musical" than solid-state designs. The "one thousand eighty degrees of phase shift" translates to a wide sweep that goes from subtle shimmer to full-on jet-plane whoosh. There are five front-panel pots, though the exact labeling isn't specified in the fact sheet. The blend control needs a B10K pot, and the others are suggested to be B100K. That level of detail in the DIY documentation suggests the circuit is sensitive to component values.
True Bypass (With a Caveat)
According to Reverb listings and user observations, the commercial Phaseur Fleur has a true-bypass circuit with an LED indicator, so when the effect is off, your signal passes through untouched. Guitar FX Layouts disagrees. It describes the DIY layout as buffered, not true bypass. Since 4ms released both commercial units and DIY designs, the bypass type likely varied between versions: true bypass in the retail pedal, buffered in some DIY builds. If you're buying used, check it, especially if you're sensitive to tone-sucking in your signal chain.
Rate LED as Status Indicator
One small but telling detail: the layout includes a rate LED that doubles as a status indicator. It’s not just there to show the LFO speed; it also tells you at a glance whether the pedal is engaged. This kind of thoughtful integration—utility baked into function—is typical of 4ms’s design ethos. It’s the kind of thing you don’t miss until you’ve used pedals that make you guess.
Mod and Custom Variants Exist
The open design has spawned modifications. One known custom version adds an extra control for output volume. That's useful, given one builder's observation that "the ring is insanely loud!" when the trimmer is turned up. The stock unit can hit high output levels in extreme settings, so a dedicated output knob is a logical upgrade for live use.
Sound and Application: From Guitars to Synths
Though marketed to guitarists, the Phaseur Fleur works on synth and bass as well. Its "smallstone-ish flavor" gives it a vintage sound, and its tweakability pushes it into more experimental territory. It's "great for guitar, synth, or bass," and it handles classic phase washes, fluttering vibrato and modulated textures that border on ring modulation. It's been categorized as both a vibe and a ring mod pedal.
Collectibility & Value
The Phaseur Fleur is discontinued and had limited production, and it has quietly gained cult status. Specific market prices aren't documented in the available research, so current value is hard to pin down. Units occasionally surface on the used market, sometimes with notes about condition, like one listing that mentions "the switch seems to be a little tired," which suggests the mechanical parts may wear over time. One builder also reported a "strange siren sound oscillating with or without any audio source," a behavior that appears tied to potentiometer values and trimpot settings. It isn't universal, but some users have had to troubleshoot it.
Schematics and build information were historically available on the Commonsound/4ms website, which makes repair feasible for the DIY-inclined. The pedal is no longer in production, so replacement parts or factory support are unlikely. Collectors should treat it as a niche item, valued more for its 4ms pedigree than as a mainstream collectible.
Builders who assembled the pedal report mixed but generally positive experiences. "The phaseur works and sounds great," one says, and another confirms "I get a good range of sounds."
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