Model 257 Dual CV Processor

Source of Uncertainty Model 257

The Source of Uncertainty Model 257 is a dual voltage processor, modeled after the 1970s Buchla Series 200 module that bears the same name. Enabling functionality such as control voltage mixing, crossfading, offset generation, and voltage-controlled amplitude scaling, it is a powerful and flexible processor that adds a significant degree of nuance and control to the 200 system's control voltage generation structures. Designed in the traditional 4U format, this module is compatible with Buchla-style 4U systems.

Each channel of the 257 is a sort of control voltage mixer with four sources. Both channels are identical in functionality. The first input for each channel features a dedicated attenuverter, allowing for signal scaling and inversion, if desired. The second and third inputs on each channel are balanced relative to one another using a crossfader-like control; this proportional balance may even be voltage-controlled. Naturally, when using only one of these inputs, it becomes possible to use the 257 as a VCA-like processor for your control voltages. One half of the crossfader may, if desired, be set to use an internal 5V reference rather than its dedicated input, useful for some offset generation scenarios. The final voltage source on each channel is a variable offset, ranging from 0 to 10V.

Each of these three processes—the attenuverter, crossfader, and offset generator—are summed together for each channel, executing the voltage processing equation shown on the front panel. While the equation might seem unfamiliar at first, it is just a description of the module's internal process, and can act as a handy reference in times of need.

The original 257 is a rare module that added a special touch of control voltage processing finesse to the original Buchla Series 200 system; the Source of Uncertainty recreation promises to add a similar level of finesse to modern 200-inspired systems.

Model 257 Features

• Dual-channel control voltage processor designed for use in modern Buchla 200-inspired modular systems
• Recreates the 1970s Buchla dual control voltage processor module
• Two identical channels
• Each channel features an attenuverter, voltage-controllable crossfader, and offset generator
• LED indication for output signal level on each channel