English: The Synthesizer control unit of the Disklavier Mark III.

This picture (looking up from the floor) shows one component of the Yamaha Disklavier player piano. The unit mounted under the left side of the piano keyboard controls the audio output of the acoustic piano and the synthesizer.

From left to right are:
Silence button; silencer indicator; knob for volume control; two headphone sockets; knob for reverb control.

When the silence button is pressed, the hammers will not hit the acoustic piano strings. The music will then be played by the synthesizer. The audio will come out on the two speakers under the piano, or the headphones if plugged in, or via the AUX line-out port to an external stereo sound system.

Most components of the system are out of sight. Other components include a row of solenoids and optical sensors mounted behind each and every piano key, the synthesizer for other non-piano MIDI voices, amplifier and two speakers mounted under the sound board.