The Befaco A*B+C V4 is a two-channel, 6HP Eurorack voltage processor that works on both audio and control voltage. Each channel multiplies two inputs and adds a third, so one compact module can cover ring modulation, VCA duties, mixing, offsets and CV shaping in a modular system.
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A × B + C per channel: two independent channels, each multiplying inputs A and B and adding signal C to the result
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Audio functions: four-quadrant amplitude modulation for ring modulation, linear VCA, signal mixer, 2x gain amplifier, phase inverter and attenuator
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CV functions: voltage-controlled attenuator, CV mixer, attenuator, inverter, VCA and DC generator
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Normalled inputs: B and C are normalled to 5V, so the module can generate fixed voltages and offsets with nothing patched
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DC coupled: handles slow modulation and static voltages as well as audio
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Signal LEDs: visual feedback on what each channel is doing
Because the same simple equation covers so many jobs, the A*B+C suits small cases and larger systems alike. Patch two oscillators into A and B for ring modulation, use an envelope on B to control the level of a signal on A, or rely on the normalled voltages to scale, invert and offset an LFO before it reaches a filter or oscillator. The V4 replaces the earlier version of the module.