The Befaco Slew is a 4 HP Eurorack lag processor and slope detector, supplied here as a DIY kit you assemble yourself. It limits how fast a control voltage can change, which turns stepped sequences into glides. It also outputs gates that show whether the voltage is rising or falling. It suits patchers who want portamento, acid-style slides, smoother modulation or simple envelopes from gates, and builders who like to solder their own modules.
-
Separate rise and fall faders: set upward and downward slew independently. A higher fader gives a longer slew.
-
Shape control: runs from a linear response to a curve that speeds up the further the input is from the output, for time-compensated portamento.
-
Three speed ranges: a range switch selects fast, medium or slow slew times.
-
CV over slew time: a three-way selector routes the CV input to rise, fall or both, and the faders then act as attenuators.
-
Slope detector: dedicated RISE and FALL gate outputs follow the direction of the output voltage.
-
Accurate pitch tracking: tracking error is stated as under 1 mV, so glides stay in tune.
On a sequencer pitch line, the Slew adds glide with independent up and down times. With the shape control turned clockwise, long jumps take roughly as long as short ones. Patch a gate into the signal input and it becomes an attack-sustain-release envelope. The rise and fall faders set the attack and release. The signal input accepts −10 V to +10 V, so it also works on bipolar modulation.
The slope detector's sensitivity follows the slew time. At the fastest settings it reacts to very small movements. If ripple produces unwanted gates, Befaco recommends increasing the slew time.