How a Typical Electronic Player-Piano System Works

EPSBasic player systems consist of:

  • a solenoid (electromechanical actuator) rail installed in a slot cut in the piano keybed (the structural part of the piano that supports the keys and action)
  • a processor unit and other electronics mounted under the piano
  • a control box that plays floppy disks and/or CDs (depending on the model), and is either mounted under the keybed at the front of the piano, or sits on or near the piano. In some models, the control box contains no disk drives and is hidden away under the piano, depending instead on your own CD player, MP3 player, or other device for the musical input.
  • a remote-control device for operating the control box from a distance
  • one or more amplified speakers, unless you choose a system configuration that uses your own speakers

On the solenoid rail, there is one solenoid for each key. There is also a solenoid for the damper pedal and, sometimes, one for the una corda (soft) pedal. Each solenoid contains a mechanical plunger that, when activated by an electronic signal, pushes against a key or against the pedal trapwork. When playing compatible specialized software, one track contains the MIDI signal that drives the piano solenoids; the other tracks provide an instrumental and/or vocal accompaniment that plays through a stereo system or through amplified speakers that come with the player system. The accompaniment may be in the form of synthesized or sampled sounds, or actual recordings of live musicians.

For recording, keystroke and pedaling information are recorded in MIDI format by a sensor strip installed beneath the keys and sensors attached to the pedals. Some systems also record hammer motion. This information can be stored for later playback on the same piano, stored on other media, or sent to other MIDI-compatible devices.

The same sensors used for recording can turn the piano into a MIDI controller. Add headphones, a device for mechanically silencing the acoustic piano, and a sound card or other tone generator, and you essentially have a hybrid acoustic/digital piano you can play late at night without disturbing anyone. Because this feature can be used independently of the player piano, most manufacturers of these systems make it available separately under such names as Silent Piano (Yamaha), QuietTime (PianoDisc), and SilentPNO (QRS). Of course, the MIDI controller can also be used with or without a tone generator to send a MIDI datastream to a computer for use with composing and editing software, among other applications. (See the article "Hybrid Pianos" in this issue for more information.)