Source of Uncertainty modules are typically based on the Buchla 266, and usually have the following sections:
- Three different colors of noise: pink, white, and blue.
- Two ‘fluctuating random voltages’ – smoothly wandering outputs – with voltage controlled ‘rate of change’.
- Two different ‘quantized random voltages’ – stepped outputs – that could either take on 1 of 7 different voltage levels (the ‘n+1’ output), or 1 of 64 different voltage levels (the ‘2n’ output). A new trigger selected a new value.
- Two different ‘stored random voltages’ that shared their own trigger input. The first one was a set of completely random stepped voltages; the second one allowed you to choose the ‘probability distribution’ of whether the voltages tended to be low, high, or in the middle of the range.
- An ‘integrator’ (slew) to smooth out changes in voltage.
- A sample & hold, with the extra feature that both the trigger in and voltage output could be alternated between two different jacks.
- One of the most celebrated random source modules is the Buchla 266 Source of Uncertainty. A significant evolution of the original Model 265, this packed module includes:
Several variations on this theme exist in the Eurorack format. The most faithful to the original Buchla is the Sputnik Modular West Coast Random Source. A close cousin is the Verbos Electronics Random Sampling, which replaces the integrator and S&H with an analog shift register. It also swaps the white noise with a ‘metallic’ output for simulating TR-808 cymbals.
The Frap Tools SAPÈL is a particularly nice evolution of the idea; its n+1 output has been quantized to octaves, and the 2n output to semitones. It offers a shared probability control to optionally affect any or all of the outputs. All of the functions also share a central clock, which may be internal, external, voltage controlled, or manually triggered. There are also random clock outputs. And, there are two of these sections in one module; their clocks can be cross-linked.« Back to Glossary Index