Maestro MPF-1

The Maestro MPF-1 is a parametric filter pedal with a mild overdrive stage, designed by Bob Moog for Gibson in the 1970s and sold under Gibson's Maestro line¹. Its most distinctive feature is a wheel-driven EQ section rather than conventional knobs: MusicRadar describes it as having "a hugely expressive, wheel-driven EQ"¹, while gearnews notes that the wheel layout "allowed for all manner of great tones, but it wasn't exactly an easy to use control interface, especially with your foot"².

The pedal is best known today for its association with Josh Homme: MusicRadar calls the MPF-1 "a favourite of Josh Homme"¹. It sits in a family of 1970s Maestro filter pedals that also includes the Maestro Filter Sample/Hold and the Maestro Parametric Filter, and its spirit lives on in the wider world of filter pedals.

The controls: frequency, height and the wheel-driven EQ

The MPF-1's control set is built around a band-pass filter whose center point, amount of boost and width are all adjustable. Godlyke Distributing, which listed the reissue, describes the three controls this way⁴:

The Filter Bandwidth switch ties the filter to the pedal's two personalities: tighter bandwidth settings (Sharp and Med) sit alongside the overdrive mode, while the Natural setting opens the filter up to a broad band. The wheel-driven interface that carries these controls is the pedal's signature, and its awkwardness underfoot is part of why players tend to set it and leave it, or adjust it by hand mid-song⁴²¹.

Filter or overdrive?

Both, in unequal measure. The technical analysis at Guitar FX Layouts, working from the service manual schematic, treats the MPF-1 as a parametric filter with an overdrive stage³. On the overdrive side, the discussion is clear about its intent:

That places the MPF-1 after dirt in the signal chain, where its filter shapes an already-driven or fuzzed signal rather than adding grit of its own. One builder in the same discussion reported that it pairs especially well with heavy fuzz: "It really takes my Fuzz Factory to a new level..."³. Players looking for a dirt pedal to feed it can read more on overdrive pedals and fuzz pedals.

From Bob Moog to the Gibson Maestro line

MusicRadar's Jonathan Horsley credits the design to Bob Moog, writing that "the MPF-1 was designed by Bob Moog for Gibson in the 1970s"¹. That puts the pedal among the handful of foot-pedal designs associated with Moog's work for Gibson's Maestro brand.

Building one: the stripboard layout

For players who want the circuit without hunting a vintage unit, Guitar FX Layouts published a stripboard (vero) layout for the MPF-1³. The layout was updated on 17 October 2015, when the IC was specified as a CD4007UBE rather than the CD4007N, with the note that the original schematic calls for a CD4007AE and the CD4007UBE is the easier part to find³. Builders have also shared a mod for the overdrive side: replacing the 5k6 resistor with a 20kb pot in series with a low ohm resistor to ground acts as a usable gain control³.

Builders in the layout's comments have documented a few practical points worth knowing before starting:

• The height control uses a 10k linear pot in the layout, where the original schematic called for an S-taper pot, which changes the control's response³.
• The frequency pot is misnumbered and backwards compared to the offboard wiring guide; swapping terminals 1 and 3 and 4 and 6 fixes it³.
• The switches are wired 1-4, 2-5, 3-6 and 1-4-7, 2-5-8, 3-6-9 with the holes facing up³.
• A usable gain control for the overdrive side can be added by replacing the 5k6 resistor with a 20kb pot in series with a low ohm resistor to ground³.

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