Brownian Drift

Designed with a focus on Pitch CV yet useful for any control voltage, this module adapts Brownian motion for adding drift to polyphonic (!) and monophonic throughput signals. Flip the upper-right switch outlined in red to replace mono jacks with poly jacks (they must be disconnected) and send your 1V/oct (pitch cv) signal through this device to imbue it with slow & subtle or quick & drastic wavering, from small analog-like variations to tape-like warble and further.

In polyphonic mode, each voice wavers independently, so some notes can run a little sharp while others run a tad flat, and together, harmonies sound thicker and more interesting. Adding drift to a 2nd oscillator can be a great way to thicken the sound. A secondary output (in both mono- and polyphonic modes) isolates the drift signal for use with other modulation destinations, so you could have filter frequencies or delay times wander with their counterpart throughput signals. A dial allows you to bias the secondary output with a -5 to +5 voltage to recenter the drift. A noise source is included so that you can add another type of randomness to the mix. Modulatable controls for rate and range allow you to set how quickly the signal wanders and how far it wanders respectively. Modulate these controls to vary the nature of the drift and add complexity. Range modulation also has a knob to vary the response from ideal for an LFO to ideal for an envelope. The “recenter” jack accepts trigger pulses to push the drift back to zero and give you control to “undrift” when desired. A second recentering mode (bottom left switch) sets the “recenter” jack to accommodate clock pulses from which the rate of drift is calculated.

It’s great for pitch cv, but it can also add complexity to LFOs and amplifiers, and the secondary drift output can be used with no input at all. Put the Brownian Drift between any modulation source and its destination to add organic, natural variation or to replicate the imperfections of various analog formats.