System Architecture

System Organization

The installation will be setup as a standalone playable instrument. It will feature user inputs through the form of buttons, knobs, gestural control, and even allow users to take control of the instrument via the internet. Through a small microcontroller and a mini-computer, the user input will be processed and sent out to the analog circuity consisting of oscillators, waveshapers, filters, and amplifiers. The signal will then be fed to speakers on the installation. Based on the pitch and timbre of the sound, the lighting of the sculpture will react accordingly, based on researched sound and light harmonic relationships. A big inspiration of the technical side of this system comes from the 1978 classic polyphonic synthesizer, the Sequential Circuits Prophet 5. It was one of the first analog polyphonic synthesizers with a digital microcontroller controlling the analog circuitry. Due to its early microcontroller implementation, it is a fairly simple and well documented system. It is also robust and well designed, there are many thousands of these instruments still working and preforming 40 years after they were built. Figure 3 and Figure 4 show block diagrams from the technical manual of the Prophet 5 depicting how the system was implemented.

Figure 1. Overview of the system

Figure 2. Overview of the processor subsystem

Figure 3. Overview of a Prophet 5 polyphonic synthesizer

Figure 4. Overview of a Prophet 5 processor subsystem

Interface Subsystem

The interface subsystem will be the digital 'brain' of the operation. It will take input, process it and send output. This system is concerned with generating and manipulating control voltages which will be fed into the analog sound generating circuity, and digital lighting control signal which will be fed into the lighting control system.

List of signal processing tasks for computer + microcontroller

Outputs

auto playing of chordal patterns when installation is inactive
autotuning of oscillators
control of led lighting

Inputs

live parameter editing
- pots, switches, knobs, gestural + sensor control
patch recall
MIDI to control voltage
external patch bay for control via new interfaces
sequencer // note storage

Potential future microcontroller tasks

software envelopes for timbre or amplitude modulation
low frequency oscillators

Sources

Jungleib, Stanley. Prophet 5 Service Manual https://medias.audiofanzine.com/files/sequentialcircuitsprophet-5servicemanual-text-470674.pdf