Overview
The Haverkamp is an electromechanical retrofit that can be installed on any acoustic piano to convert it into a player piano (self‑playing piano). Designed and built in the Netherlands in the 1980s and partly updated in the 1990s, the system uses 85 MIDI-controlled solenoids to actuate the piano keys. It has been donated to the Department of Musicology, which is preserving the unit in working condition.
Storage and Handling
The Haverkamp is stored in the Synthroom inside a wooden box. The wooden enclosure is clearly marked to show which side must be kept up at all times during storage or transport. Photographs show that the Haverkamp inside the enclosure must be kept with the solenoid plungers facing up.
To open the wooden enclosure, remove the four screws at the top‑right corner (Torx or Allen key required). The box also contains the Haverkamp power cable and several wooden spacers used to prevent the Haverkamp from moving inside the box and to mount it on top of a piano (these are painted pink).
A second, smaller flight case containing spare parts and the two safety clamps used to secure the Haverkamp to a piano is stored in Basement 2 of the Department of Musicology, ZEB building.
Because of its size, weight, fragility, and age, the Haverkamp must always be handled by at least two people. The Haverkamp has no handles. Handle it by the wooden frame at the short edges only — do not apply pressure to or lift by the solenoids, electronic boards, or any delicate brackets. Never tilt the storage box on its side or upside down when removing or returning the Haverkamp. Always keep the box upright with the solenoid plungers facing up during handling, transport, and storage.
Installation
The bottom of the Haverkamp (the side with the solenoids) has four rubber feet that rest on the piano’s key cheeks; because the Haverkamp is shorter than a standard 88‑key keyboard (it fits an 85‑key length), you must extend the left key cheek using the two pink wooden spacers stored in the Haverkamp box (as visible in the pictures below)
Always have at least two people lift the unit, with a third person acting as spotter and director to monitor solenoid alignment over the keys; lift only by the wooden short edges and never by the solenoids or electronic boards. Lower the unit slowly and vertically so the solenoid plungers sit squarely on the white and black keys—do not set it down while slanted, diagonal, or tilted, as improper placement can bend the plungers. Finally, install the two safety clamps (kept in the flight case in Basement 2) in front of the keyboard to secure the pink spacers and help prevent accidental movement or tipping; proceed slowly and communicate clearly throughout the process.
Power
Before powering the Haverkamp, ensure nothing obstructs the full travel of any solenoid; powering the unit while a plunger is blocked can damage the solenoid driver. Do not power or operate the Haverkamp while it is resting on the floor, as there is insufficient clearance for plunger movement.
Connect the five‑pin black power connector to the Haverkamp (it is keyed and will only seat correctly when oriented properly). The power cable contains five conductors with the following functions and minimum voltage/current requirements:
- the two black wires are ground (GND) and are shorted together inside the Haverkamp;
- the blue wire is +5 V providing at least 1.5 A for the digital electronics;
- the red wire is +12 V providing at least 15 A for the attack needed to initiate key strikes;
- the green wire is −30 V providing at least 8 A for sustaining notes (holding a plunger in the struck position).
With these supply ratings the system can drive up to about 20 keys simultaneously.
To provide the required voltages and currents you must use the three bench DC power supplies available in the Makerspace; the supplies are not identical and are not interchangeable. The TENMA supply (white, on the right in the photos) must be used for the +5 V; the MY‑K1520MF (black, in the middle) must be used for the +12 V; and the KUAIQU (black, on the left) must be used for the −30 V.
Place the three supplies on top of the piano and connect the cables as shown in the pictures: the blue cable to the + (positive, red) terminal of the TENMA, the red cable to the + (positive, red) terminal of the MY‑K1520MF, the green cable to the − (negative, black) terminal of the KUAIQU, and the two black cables (in any order) to the − (negative, black) terminals of the TENMA and the MY‑K1520MF. Also use the black wire with yellow connectors (stored in the Haverkamp box) to link the + (positive, red) terminal of the KUAIQU to the − (negative, black) terminal of the MY‑K1520MF.
Configure each supply to the required voltage and current limits before enabling its output. If you are uncertain about the voltages, disconnect the Haverkamp power connector and verify each supply with a multimeter before connecting the unit.
Operation
Connect the MIDI cable to the Haverkamp’s rear MIDI Input port; a MIDI Through port is also provided to forward received messages.
First turn on the power switch for the digital electronics to enable MIDI reception and forwarding, then turn on the solenoid power switch (the solenoid supply is indicated by a red LED).
If any solenoids are stuck or fail to move, power‑cycle the solenoid supply or the entire unit. The numeric display shows the current MIDI channel and the adjacent button was originally intended to change channels, but this function is no longer operational: the Haverkamp is fixed in Omni mode (MIDI channel 0) and responds to Note On/Off messages on any MIDI channel. Do not leave the Haverkamp operating unattended; if you observe voltage drops on the power supplies, turn everything off immediately, as that indicates excessive current draw which may damage electronic components.
The Haverkamp responds to MIDI Note On/Off messages in the pitch range 21–103.
Documentation
A ZIP file containing the original design files and schematics for the Haverkamp is available here.
Known Issues
Two diodes are missing and replacement diodes blow immediately because the unit draws a large current from the +12 V rail; this likely indicates either one or more shorted solenoids or additional failed diodes downstream. To troubleshoot, measure the DC resistance of individual solenoids — each should read approximately 16–18 Ω. The solenoids used in the Haverkamp are Shin‑Etsu (Shinengen) F25027L.8850.
The MIDI‑channel selection button is nonfunctional and its wiring is currently disconnected. This does not prevent operation because the Haverkamp is fixed in Omni mode (it responds to Note On/Off messages on any MIDI channel), but if single‑channel operation is required the button’s wiring should be reconnected; the exact connection point is unclear from the available schematics.
The wiring that supplies +12 V and −30 V to the solenoids is intermittent: sometimes the unit does not respond at all, and other times only the attack (driven by +12 V) works while the sustain (−30 V) does not draw current. Inspect and test the power wiring, connectors, and relevant PCB traces to locate any loose or corroded connections and repair or replace the faulty connector or board as needed.
Velocity response is inconsistent on several keys, which may be caused by aged or partially bent solenoid plungers. After verifying electrical integrity and connector stability, inspect and, if necessary, repair or replace suspect solenoids and ensure plungers move freely and return correctly to restore consistent velocity response.