Electro-Harmonix Electric Mistress Flanger/Filter Matrix

The Electro-Harmonix Electric Mistress is an analog flanger pedal from the mid-1970s, and the original 1976 design was the first time this wobbly effect was housed in a pedal enclosure, according to Guitar World¹². Alongside the MXR Flanger and the Boss BF-1, it was among the first flanger pedals ever released, arriving by the mid-1970s as pedal makers began putting the studio tape-flanging effect into stompboxes². Premier Guitar calls the 1976 original the first commercially available flanger³.

What set the Electric Mistress apart from other flangers was its Filter Matrix mode, which stops the sweep and turns the pedal into a manually tunable bank of filters. Vintage units are no longer available new, and the pedal's later descendants, including the Deluxe Electric Mistress and the Andy Summers signature model, have themselves been discontinued⁴⁵⁶.

The controls: Color, Range, Rate and Filter Matrix

The Electric Mistress control set is small and consistent across its versions. Guitar World lists the Deluxe Electric Mistress controls as Color, Range, Rate and Filter Matrix¹, and MusicRadar reported that the Deluxe Electric Mistress XO packed the same color, range and rate controls plus the Filter Matrix switch⁹.

On the Stereo Electric Mistress, the depth knob controls the amount of flange mixed with the direct signal¹⁰. Premier Guitar's review of the Stereo Electric Mistress noted that Electro-Harmonix found a clever way to combine the Filter Matrix with a normal rate control sweep into one pot¹¹.

What Filter Matrix mode does

Filter Matrix is the Electric Mistress's signature trick. As Guitar World explains it¹²⁵⁴:

In Filter Matrix mode, the pedal stops the LFO and holds the flanger's frequency cancellations where they are, mid-sweep, instead of sweeping them. The result is a set of static, metallic resonances rather than the usual moving jet sweep, and because the cancellations are frozen rather than moving, the Range knob lets you tune where those resonances sit⁴. Players use it less as a traditional flanger and more as a fixed filter bank, sitting somewhere between a resonant wah parked in one spot and a ring-modulator texture.

Guitar World's modulation history describes the setting as one that deactivates the delay modulation. Premier Guitar's press coverage of the Deluxe Electric Mistress XO put it in circuit terms: in Filter Matrix mode the modulation waveform is disconnected from the flanger circuit, freezing the flanger and creating a matrix of filters¹³. Electro-Harmonix's own description of the Stereo Electric Mistress says Filter Matrix mode lets you manually flange your sound or select a flange point, allowing what the maker calls musically frozen tonalities¹⁰.

The sound of the mode is distinctive enough that MusicRadar's reviewer of the Mooer Eleclady, a compact take on the Mistress circuit, singled out "even that signature metallic whine you get when switching a Mistress to Filter Matrix mode"¹².

Flanger or chorus?

The Electric Mistress is a flanger, but its range overlaps with chorus. MusicRadar's Alex Lynham, reviewing the Andy Summers signature pedal, wrote¹⁴¹⁵:

Electro-Harmonix leans into this on the Stereo Electric Mistress, listing it as a Flanger/Chorus and describing lush stereo flange and chorus working together¹⁰. Andy Summers himself, interviewed about his signature pedal, said he would have called it a chorus¹⁵.

A 1970s flanger and its later versions

The Electric Mistress arrived in 1976 as the first flanger in a pedal enclosure¹⁸. Electro-Harmonix delved into time-based effects in the mid-seventies with the Electric Mistress flanger, as Mike Matthews recalled to Premier Guitar¹⁶. A later "V2" version ran on 18 volts in the late '70s, the circuit that PastFx used as the basis for its Elastic Mattress flanger¹⁷.

The originals have a mixed reputation for reliability. Premier Guitar's review of the Hartman Analog Flanger, a modern pedal based on the Mistress, was blunt⁸:

JHS Pedals calls the Electric Mistress a classic and absurdly expensive analog flanger of the past¹⁸. Pedal of the Day describes it as an extremely coveted piece of flanger history, in all of its iterations¹⁹.

The line continued in several forms:

• Electric Mistress: Electro-Harmonix's flanger with a Filter Matrix mode, released in the mid-seventies; the original 1976 design was the first time this wobbly effect was housed in a pedal enclosure¹¹⁶
• Electric Mistress V2: based on Electro-Harmonix's late '70s 18-volt Electric Mistress flanger¹⁷
• Stereo Electric Mistress: an updated version of the company's classic from 1976, the first commercially available flanger³
• Deluxe Electric Mistress: the Filter Matrix switch was one of a number of mods developed for the Deluxe Mistress over the earliest '70s and '80s years²⁰

Electro-Harmonix closed its doors in the 1980s, as PastFx notes on its own Deluxe Elastic Mattress page, before the brand returned and carried the Mistress line forward²¹.

On video

That Pedal Show compared six flangers in a 2016 episode, with the Electro-Harmonix Electric Mistress Flanger/Filter Matrix as loop 4, its discussion and sounds starting at 5:25, where Daniel Steinhardt and Mick Taylor demonstrate the unmistakable sound of a 1970s Electric Mistress⁶²².

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