The Tetrazzi Organus was the precursor to Ciat-Lonbarde's current Tetrax. The Tetrazzi is a four voice "organ" with a sound that ranges from string-like to noisy breath-like sounds. It is an extremely expressive and gestural instrument, something to continually interact with and explore. I've had it for 15 years now, and I still find new subtlies every time I play it. Play and control: Each voice is controlled by pressure on a touch sensitive "barre" - the four strips of wood that make up the top surface of the instrument. Pressure on Each barre opens and closes an envelope for each voice as well as controlling the stereo pan of the voice, pressure on the barre triggering the rise of its envelope and leftward pan of the voice, release of pressure on the barre triggering the release of its envelope and rigtward pan of the voice. The barres are very sensitive for exceptionally expressive playing. The central pitch of each barre is set by pressing the four buttons at the front of the instrument. Tapping a button sets the pitch of it's barre to the current pitch of a cluster of oscillators in a feedback loop, pressing each button in succession will result in a random but related series of pitches for each voice. there are four finger wheels, two on each side of the instrument that interactively effect both pitch and waveform of the four voices. the voices themselves range from almost sub-bass to above audio range, depending on the current settings of all of the controls. Each barre also has several brass screw touchpoints with which you can control intermodulation between the four voices. Modifications: on the tetrazzi's circuit board are several points where optional capacitors or resistors can be added to change it's four voices. Instead of adding fixed values to these points, I've connected them to the pins of a DB-25 connector so that parts can be swapped out externally if desired. Components can be insreted into the corresponding holes in the connector loosely (which can make for intermittent changes since they are not soldered in) or they can be soldered into a corresponding DB-25 connector to create a cartridge of sorts for more stable connections. No additional parts or DB-25 connectors are included, you will need to obtain these yourself and experiment! This Tetrazzi was assembled by me from a kit from Ciat-Lonbarde. the PCB was pre-assembled and tested by them, and the final assembly, finish, and modification was done by myself. The barres are made of Yew, and the body is made of various other woods. All of the wood components are finished with tung oil. The audio output is a single stereo 1/4 jack Power is either by 9v battery or 12v DC 200ma tip positive 2.5mm plug wall wart (not included)