Rane MPE-28 (c. 1989)
Twenty-eight bands of analog EQ with a MIDI brain. A one-channel, 1/3-octave curve machine that was doing preset recall before most studios had a computer.
Overview
The MPE-28 is a single-channel, 28-band, 1/3-octave programmable equalizer from Rane Corporation. It sat at the top of the company's MPE series of MIDI-programmable graphics. The MPE-14 packed two channels of 14 bands at 2/3-octave, and the MPE-47 spread four channels of 7 bands at full octave. The MPE-28 went narrow and deep: 28 bands at 1/3-octave spacing on one channel, the tightest resolution in the family. Rane's own literature framed the series as the beginning of "a generation of automated signal processing" from the company. That reads like a line to take with a raised eyebrow, until you remember this was 1989 and an EQ with recallable memory was new territory.
Collectors like the MPE-28 for mixing old and new thinking. The filters are analog. They use Rane's "interpolating constant-Q" design, which held a consistent Q as bands were boosted or cut, rather than the broad, smearing response you got from cheaper graphics. The control layer is digital: 128 storable memory locations, each curve recallable via MIDI program change commands, with editing done through MIDI system-exclusive messages. Each band adjusts from +12 dB to -15 dB in 1 dB steps, and there's an overall level trim of ±12 dB in 2 dB steps. The unit is digitally programmable end to end, which was a serious thing for a 1989 single-rack graphic EQ.
Documentation is thin. Most of what survives is trade-press coverage from the launch window, and even that is sparse. Recording Engineer (April 1989, p.51) covered the MPE series when Rane exhibited it at a pro-audio booth, and that report remains the best single description of what the MPE-28 actually did. Rane's own advertising ran through 1990 and 1991. The source material references an EQ (July) ad but is truncated there, so no usable content survives from it. The MPE-28 is better documented in a couple of trade-show writeups and a service manual than in any consumer-facing literature.
Key Features
28 Bands at 1/3-Octave Spacing
Twenty-eight bands in a single channel is a lot of resolution. At 1/3-octave spacing the MPE-28 gives you the kind of granular control usually reserved for a dedicated monitor or FOH graphic, and it's the reason the model sat at the top of the MPE line. The MPE-14 traded band count for a second channel. The MPE-47 traded everything for four channels of octave-band control. If you wanted to carve a single source with precision, the MPE-28 was the pick.
Interpolating Constant-Q Filters
Rane's "interpolating constant-Q" filter topology is the technical core of the unit. Constant-Q means the filter's bandwidth stays consistent as you push a band up or down, so a deep cut doesn't turn into a vague, wide scoop the way it does on lesser graphics. The "interpolating" part of the name is Rane's own terminology from the period, and whatever the exact mechanism, the design intent is clear: keep the EQ surgical rather than smeared. Collectors who've used both the MPE-28 and generic 1/3-octave graphics tend to describe the Rane as the more precise tool. Period owner reports on sound quality are essentially absent from the surviving record.
128 Memory Locations with MIDI Recall
The MPE-28 stores 128 EQ curves, and each one is recallable via MIDI program change commands. That was the feature that made the unit interesting in 1989, and it's the one that keeps it useful in a MIDI rig today. An EQ that can switch curves on cue, driven by a sequencer, a foot controller, or a rack brain, was a different proposition from a knob-and-slider graphic. Curves are edited via MIDI system-exclusive messages. The speed at which the unit changes between curves is user-definable, which helps if you're switching mid-performance and don't want an audible jump.
Curve Combining
Two stored curves can be combined into a new curve using a built-in program. It reads like a footnote until you use it: layer a room-correction curve over an instrument curve, or build a hybrid from two presets you already trust, without starting over.
Analog Signal Path, Digital Control
The MPE-28 keeps its audio path analog while putting the memory and recall under digital control. That split is the whole appeal of the MPE series, and it's why the unit shows up in rigs where a purely digital EQ would have been the wrong tool. The Recording Engineer (April 1989, p.51) coverage describes the series' programmable gain control and full MIDI mapping alongside the analog filter design.
Historical Context
The MPE series launched into a market that was just beginning to take MIDI seriously as a control protocol for signal processing. Recording Engineer (April 1989, p.51) reported the MPE-28 alongside the MPE-14 and MPE-47 as a three-model family, with the MPE-28 as the 28-band, 1/3-octave flagship. Rane positioned the series as the start of automated signal processing from the company. The timing lines up with a broader industry push toward recallable, MIDI-addressable outboard gear.
The MPE-28's afterlife is more interesting than its launch. It turns up in Def Leppard guitarist Phil Collen's documented effects list, alongside a DigiTech GSP 21, Rockman XPR, TC Electronic 1128 EQ, and BBE 442 Sonic Maximizers — a rig that reads like a snapshot of late-'80s rock guitar processing. It also appears in a NASA technical report test setup, listed as "Rane MPE-28 Programmable Equalizer" alongside a QSC 1700 power amplifier, which is the kind of placement that tells you the unit was trusted for measurement-grade work and not just stage rigs. And it's listed as a supported device in MOTU's Unisyn MIDI librarian, which means someone at MOTU thought enough of the MPE-28 to build a device profile for it.
Production years are not documented beyond the "c. 1989" reference and the April 1989 trade-press citation. The end of production is unknown.
Collectibility & Value
The MPE-28 is not a hot collectible, and the market reflects that. No exact listings were live on eBay at the time of research. A Reverb Canada listing described a used-good unit as "Originally C$4,800, now C$3,500". That original figure is ambiguous and may reflect a prior listing price rather than the unit's actual retail, so treat it with caution. A Spanish classifieds listing offered two MPE-28s at €125 each, which is closer to the realistic street range for a working unit. Service manuals are available in English from at least one Russian vendor, and user manuals run five pages (or 34 pages for the combined MPE manual), which helps anyone doing a repair.
No common failures, repair notes, or maintenance warnings surfaced in the research. The unanswered Harmony Central forum inquiry, asking whether preset switching causes signal dropout, is the closest thing to a user concern in the surviving record, and no owner response was captured. Buyers should verify preset-switching behavior on any unit they're considering, since that's the one operational question the documentation doesn't answer.
eBay Listings
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