Dual Voltage Processor (2025)

Dual Voltage Processor is a general-purpose control voltage signal scaler, combiner, and linear voltage range re-mapper for the [Nonlinear] Dynamics system. It features two distinct channels (A/B and C/D), each with an identical feature set. It is optimized for use with control voltages, and is not especially suitable as a processor for audio signals. It was inspired, in part, by Donald Buchla’s 256e Quad Control Voltage Processor and aspects of the 281 Quad Function Generator.

Functional Explanation

For the sake of explanation, we will focus on the first channel—however, keep in mind that each channel is identical in functionality. The first channel’s primary inputs are labeled A and B, respectively. The A Scale and B Scale knobs act as attenuators for the incoming signals. A +5V offset is applied to the normalled jack connections on both the A and B inputs; this connection may be broken by patching into the jack in question. The Scaled input signals are then passed to the Source Blend section.

The Source Blend parameter, the Select control voltage input & attenuverter, and the Mode Select switch act in tandem to define the behavior of the channel in question. In Linear Mix mode, the Source Blend parameter performs an inverse linear scaling for the A and B inputs, respectively—that is, as the Source Blend knob is rotated clockwise from its full counterclockwise position, A’s signal level will decrease as B’s increases, until only B is present at the output. The Source Blend parameter may be dynamically modulated using the Select (Sel) input and associated attenuverter. All together, these features enable even a single channel of Dual Voltage Processor to act as a crossfader, VCA, or as a simple control voltage mixer. Given that the two principal inputs for a given channel also offer normalled input connections from a +5V offset signal, it is also possible to use one channel as a combination scaler/offset generator.

Comparison mode behaves somewhat differently. The Source Blend and Select input act as before, determining inversely-correlated scaling factors for both principal inputs from a given channel. However, rather than passing the sum of the scaled signals to the output, it instead performs a “maximum” signal level comparison of the two channels—selecting between the two scaled signals and only producing the higher of the two signals.

Through this combination of features, Dual Voltage Processor may be used as a simple attenuator, an inverter, an attenuverter, an offset generator, a VCA, a crossfader, a multidirectional panner, an analog logic processor, and more.

Voltage Range Remapping

One especially interesting application involves its use as a voltage range re-mapper—which further enables the generation of tendency masks. The voltage range re-mapping is specifically inspired by the Buchla 256e, which offers an unusual approach to offset generation, attenuation, and inversion by allowing users to specify a “transfer function” in which input signals’ minimum possible level and maximum possible level may be linearly remapped to arbitrary output values.

This function can also be achieved with Dual Voltage Processor. Set the Mode to Linear Mix; ensure that no external signals are connected to the A or B signal inputs (enabled the internal connection from a +5V offset). Set the Source Blend knob fully counterclockwise. Set the Select attenuverter fully clockwise, and then send a control voltage to the Select input. The voltage range remapping function can now be achieved by adjusting the A Scale and B Scale controls; 0V at the Select input will “select” the voltage offset corresponding to the A Scale control, and 5V at the Select input will “select” the voltage offset corresponding to the B Scale control. Any intermediate voltage will produce the weighted average of the A Scale and B Scale knob settings.

One may use this patch to achieve offset functions: e.g., by turning A Scale to 50% and B Scale to 100%, an incoming voltage of 0–5V should be produced as ~2.5–5V, with its shape maintained. Likewise, if the A Scale control is higher than the B Scale control, the voltage range will be remapped and the outgoing signal’s phase will be inverted with respect to the input.

Tendency Mask Generation

This patch may be extended in order to facilitate tendency mask generation. For conventional tendency mask generation, you would send a relatively quickly-changing random signal to the Select input, and relatively slow-changing signals into the A Scale and B Scale inputs—performing dynamic voltage level remapping. This is the same process as described in the preceding paragraph, however, you are now “modulating” the upper and lower boundaries of the output voltage range. In the [Nonlinear] Dynamics system, it can be especially interesting to use the Trajectory Generator or Voltage Mapping Array to define the changing boundary levels for the tendency mask.

Version Changes

Dual Voltage Processor has gone through multiple prototype stages; it was originally 17HP in width, but more recent versions maintain the same feature set at only 14HP (with only relatively minor ergonomic drawbacks).

Dual Voltage Processor is a concept/prototype, developed primarily for personal use. It is not available for purchase.