Like the harmonium, the Harminium has a primary keyboard and two drones. The instrument is held in the left hand and played primarily with the right. The keyboard is composed of three keys on top, played with the first three fingers. These three keys, played in combinations, produce a diatonic scale. The thumb of the right hand can play either of two buttons on the left side of the instrument. The top button raises any note by one octave, the lower button lowers any note by one octave. On the right side of the instrument (out of view in this picture) is another button that can be pressed by the second finger of the left hand to raise any note by 1/2 step. This allows the 6-button instrument to have a 3 octave chromatic range.
Three brass knobs are visible on the left side of the instrument. The top one is on/off and volume. The bottom two allow you to tune the two drone notes to whatever harmony you prefer. The speaker is mounted behind the carved sound hole in the top, and a small red LED below that indicates power is applied. A panel on the bottom can be removed to install a 9 volt battery, so the instrument is self-contained and portable. An output jack allows you to plug it into a larger amplifier for miniature, ear shattering performances.
On the right side of the instrument are several other controls including:
On some versions a knob is added to the top that allows 10-turn tuning of the primary scale to any arbitrary pitch or key.
The instrument shown is made from figured koa with a red cedar face and ebony keys. My original instruments (made in the mid '70s) utilized digital square waves for all oscillators. This allowed precise tuning and a reedy sound that is not unlike bagpipes or the original Indian harmonium. I'm now experimenting with microprocessor controlled wave tables that produce more variety of timbre.