Roland RD-100
Eighty-eight weighted keys, a black stage finish, and twenty-four kilograms of late-nineties digital piano that the used market still hasn't decided what to do with.
Overview
The RD-100 is a stage piano, and it makes no secret of it. Roland's own documentation calls the finish a "black stage look" - no wood veneer, no furniture styling, nothing that pretends this thing belongs in a living room. It measures 1360 x 121 x 346 mm and weighs 24.0 kg. That's heavy enough that one person can move it, and light enough that two people will still argue about who carries the ends. The keyboard is a full 88 keys with a hammer action mechanism, and the sound source runs 64-voice polyphonic. For a late-nineties digital piano, that polyphony figure is the headline. With 64 voices, sustained piano passages with the pedal down don't start stealing notes from each other the way earlier generations did.
The tone list is narrow. Piano1, Piano2, Harpsichord, Vibraphone, El. Piano1, El. Piano2, Pipe Organ, Strings, and Honky Tonk - the last of which is only available in Dual mode. That's nine sounds. There's no expansion, no card slot documented in the manual, and no sample library to chase. What you get is what's in the wave ROM, and the machine is built around the first two entries on that list. The keyboard action offers three touch levels - Light, Medium, and Heavy. A heavy setting on a hammer-action board is what makes the thing feel like an instrument rather than a controller.
Roland gave the RD-100 an unusual tuning section for a stage piano of this class. Alongside standard Equal Temperament, the manual documents Pythagorean, Just (Major/minor), Mean Tone, Werckmeister, and Kirnberger temperaments, plus two types of Stretch Tuning. On a gigging board aimed at pop and rock players, that's an odd amount of historical tuning theory. It suits players who came from a classical background and wanted something that didn't sound wrong on early music. Key transpose runs -6 to +5 semitones, adjustable either by keyboard entry or button entry.
The onboard sequencer is a two-track affair with a track muting function and roughly 5,000 notes of capacity. Two tracks is not a workstation. It's a sketchpad, or a way to lay down a bass part and a piano part for a solo gig without dragging a second keyboard along. The metronome covers 0/4, 2/4, 3/4, 4/4, 5/4, 6/4, 7/4, 3/8, 6/8, 9/8, and 12/8, with seven volume levels and a tempo range of 20 to 250 BPM. That range is wider than most players will ever need.
Digital effects are Chorus with seven types and Reverb with seven types. That's not the usual three or four presets, and it's not a full parameter-editable effects engine. The display is a 7-segment LED, three characters. That's minimal, and it means every function on this board is reached by button combinations rather than menus.
The jack complement is practical and nothing more: two stereo headphone jacks, stereo/mono output jacks, MIDI In and Out, and a pedal jack. The pedal jack is stereo, and the damper pedal is standard while Soft is only available via a special break-out cable. Know that before buying used. The RD-100 ships with a pedal and cable, and finding a replacement break-out cable for the Soft function is not necessarily straightforward. Power consumption is listed at 8W across all voltage variants - 100V, 117V, 230V, and 240V - which is low and means the board runs cool and can be powered from almost anything.
Roland's service documentation for the RD-100 is dated February 1999, and it's thorough. Test Mode is entered by pressing Transpose, Play, and Track 2 simultaneously after power-on. The 7-segment display then shows "JIG" and the CPU runs a device check covering ROM, SRAM, Wave ROM, and DRAM. If everything passes, the display shows the ROM version - 1.0.5 in the documented example. The test routine walks through button and LED checks, effect checks, an A/D check for the damper and soft pedals (with values from 0 to 10 displayed and a sine wave or bell sound confirming each), and a MIDI check that requires physically looping MIDI Out back to MIDI In with a cable.
On the repair side, the manual is blunt about the power supply: the SWM18N switching power supply is replaced as a unit, with no individual parts available. That's a common late-nineties approach. A failed PSU is a module swap rather than a component-level repair. The main PCB assembly carries part number 7700903000, the jack board is 7700902000, and the control board is 7699401000.
The RD-100 isn't a workstation, a sampler, or a synth. It's a piano that happens to have MIDI and a two-track sketchpad. The 64-voice polyphony and hammer action put it up against the digital pianos of its era, and the nine-sound palette keeps it focused. Players who want a stage piano that does one job will find a lot to like. Players who want a do-everything board will find the three-character display and button-combination interface maddening.
The RD-100 shares its engine lineage with the MKS20 rack module. Period classified listings in the UK press described the MKS20 as an "RD 100 in a rack" (Sound on Sound UK, November 1996, p.260). That means the RD-100's sound is the same sound that showed up in a lot of studios in rack form, just with keys attached.
The hammer action mechanism is the wear point on any weighted-key digital piano, and the RD-100 is no exception. Key weights, contact strips, and the felt and grease in the action degrade with age and use. The 7-segment display is a simple part and rarely fails. The switching power supply is the single most likely failure point on a 25-year-old board, and since it's a unit-replacement item, a working spare is worth more than its weight in scrap. The stereo pedal jack and the special break-out cable for Soft are the two accessories most likely to be missing from a used example.
The RD-100 sits in an awkward spot in the used market. It's not a vintage analog classic, so it doesn't command collector prices. It's not a current-production stage piano, so it doesn't have modern sample libraries or USB audio. What it has is a good hammer action, 64-voice polyphony, a nine-sound palette, and a build that Roland expected to be serviced rather than discarded. It suits a player who wants a weighted 88-key board for home practice or a quiet gig and doesn't need a thousand sounds.
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