The Befaco Voltio is a 6 HP analog voltage source and precision adder for Eurorack. It sits somewhere between a musical tool and lab equipment. Modular players can use it to tune oscillators to known intervals and transpose sequences. DIY builders and anyone who maintains analog gear get a dependable reference voltage for calibrating oscillators and filters.
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Chromatic 1V/oct voltages: two controls dial in every note of the 12-tone equal-tempered scale across a ten-octave range.
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Octave and semitone controls: each octave step adds or subtracts 1 V, and a 12-position semitone switch moves in 83.3 mV steps.
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Unipolar or bipolar range: a switch selects 0 V to 10 V or -5 V to +5 V output.
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Precision Sum In: adds an incoming signal to the set voltage, to offset CV or transpose a sequence or arpeggio.
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Multimeter connectors: two 2 mm banana sockets, one carrying a copy of the output and one at ground, take standard test probes for hands-free measurement.
In a patch, Voltio is a simple way to set precise pitch relationships. Set two oscillators a fixed interval apart, or feed a sequencer or arpeggiator into Sum In and shift the whole phrase by octaves and semitones without reprogramming it. The adder also takes other external signals, such as an LFO, and places them at a chosen offset.
On the bench, the banana connectors take the multimeter leads while both hands stay free for trimming a VCO or filter. Retailers also suggest using them with an oscilloscope, or using the module as a voltage source when breadboarding. The circuit is fully analog, and Befaco recommends about 30 minutes of warm-up for best accuracy.
Voltio is designed in Barcelona, and Befaco publishes its schematic and build documentation. This listing is for the assembled module.