40xx Synth

Synthesizer exploring digital logic through 4000-series CMOS circuits

The 40xx Synth materializes our fascination with boolean logic and music. The instrument is based on a different set of ideas compared to most traditional synthesizers. Instead of scales and harmonies, it makes use of binary counters, multiplexers, and shift registers that can all work together to shape multilayered rhythmic structures.

All the logic operations are based on the division of its six basic oscillators. This approach can be thought of as an extremely primitive musical computer, and all of the internal circuitry would have been available in the 1970s.

The instrument is heavily inspired by so-called “Lunettas” named after the percussionist and sound artist Stanley Lunetta who created musical sculptures using simple CMOS circuits.

The circuits included in the instrument are as follows: six oscillators, four XOR gates, four AND gates, two 10-Bit ring counters, two 12-bit binary counters, one 8-bit shift register, two 8-bit multiplexers, and one 5 channel mixer.

Through this instrument, we are interested in exploring how the architecture of the circuit itself will shape the architecture of the music it creates.

State Machine - a Virtual CMOS Synth

To both further deepen our approach with computational logic and synthesis, we’ve put together a virtual online instrument called “State Machine” which acts very similarly to the original 40xx. You can create and patch on an infinite canvas of boolean logic modules, and listen to the result. The output is always a single bit-stream of ones and zeros with no additional process (so expect some artifacts from that too!).

You can save and load patches to your computer. Be careful when you turn on your audio - the instrument always plays at full volume.

Check it out and enjoy!

Audio Demos (Direct instrument signal)

For us, this logic approach is all about pushing the limits of what we can achieve from these simple rules, avoiding any traditional synthesis techniques when possible (voltage control of filters, oscillator pitch, etc.) Here’s same example sounds created with the raw output of the 40xx Synth, each represents a single patch turned on for one minute, with little to no intervention from the player.