Musitronics Mu-Tron Flanger

The Mu-Tron Flanger is a flanger pedal made by Musitronics in the late 1970s. Mike Beigel invented it in 1977, according to Dave Hunter's GuitarPlayer history of the company, and the production unit was manufactured in 1978 as a pedal-controlled unit¹²³. What sets it apart from most flangers of any era is that it carries its own built-in foot control: Musitronics called it the Pedal Flanger, and its Opti-Pot treadle sweeps the effect's parameters after you dial in their initial settings²⁴.

The pedal is long out of production, and vintage examples now change hands at high prices. GuitarPlayer's Dave Hunter wrote that Musitronics products "both of which now fetch major bucks on the collectors' market"¹.

The controls and the treadle

The Flanger's Sweep Start control sets the amount of delay at the start of an LFO sweep, which determines where the flanging effect begins its travel². The sweep rate runs from .05Hz to 20Hz, and the delay time covers 0.6 mS to 24 mS².

The distinctive part is the treadle. Premier Guitar's history of modulation effects noted that "the Flanger has parameters that are manipulated, after their initial settings, by a treadle"⁴. In practice that means you set the sound with the panel controls, then rock the built-in pedal to sweep the effect live, the way a player might use a wah pedal.

The Opti-Pot pedal

Musitronics built the foot control into the pedal itself rather than expecting players to attach a separate expression pedal. The maker described the Opti-Pot as "smooth and reliable," and said it "stays free of hum and noise under all types of lighting and environmental conditions"². Optical pedal control of this kind avoids the wear and noise that a mechanical potentiometer treadle can pick up over time.

Power and specifications

The Mu-Tron Flanger is not a battery or standard pedalboard supply pedal. The maker describes it as AC powered, with low-noise circuitry, and claimed it "delivers the cleanest studio quality flanging on the market, at any price"². The published specifications also give an input impedance of 390k ohms unbalanced, an output impedance of 600 ohms unbalanced, a dynamic range of 100db, and a sweep rate of .05Hz to 20Hz².

Where it came from

The production Flanger followed a series of Musitronics prototypes. A flanger built in an Octave Divider package dates from 1977-78, and the maker's history notes that "The Mu-Tron Flanger was manufactured in 1978 as a pedal-controlled unit, not this package style"³. The company had also experimented with flanging in earlier prototype units before settling on the pedal format³.

What it does to a sound

Musitronics advertised the Flanger as covering more than jet-style flanging alone. The maker claimed "a wide variety of effects like slap-back echo, card-board tube, hard reverb, vibrato, and double tracking"². With 24 mS of maximum delay time available, the sweep range reaches into territory that shorter-delay flangers cannot, which is what makes effects like slap-back echo and pseudo-reverb possible from a modulation circuit.

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