Abstract: Musical bellows instrument comprising an electro-pneumatic switching device, operated by the change in air pressure generated by the bellows movement to control a set of control gates for the registers, sets of registers or effect circuits of the musical instrument. The switching device comprises a fixed section secured to the instrument and a movable section secured to a flexible membrane sealing in an opening communicating with the interior of the bellows.

Abstract: An acoustic signal generator circuit produces electrical acoustic signals ose frequency spectrum and envelop curve respectively determine the acoustic parameters, pitch and timbre and, respectively, the change in amplitude with time and accordingly the volume, attack and decay phenomena and also quasi stationary behavior of the corresponding sound. There is a manually actuated control device for influencing at least one part of the acoustic parameters. The control device can be constructed in a manner similar to an accordion with a blow bellows and at least one keyboard.

Abstract: An electronic circuit connected to and operated by the bass buttons of an accordion to simulate a string bass instrument. The circuit can be disposed in the accordion or remote from the accordion. Each button has a switch associated therewith which couples to means for generating a fixed frequency signal indicative of the actuated button. Signals over a two octave range may be generated and logic circuitry is provided to effectively expand the single octave of available buttons to greater than the single octave such as by a half octave expansion. Output circuitry shapes the output audio signals to allow more or less of the harmonics to pass. A special bass pluck circuit is also provided.