The IN socket is the input for signals to be processed. Gate and Trigger signals at the TRIG input cause the module to produce one rise/fall cycle what can be considered an Attack/Decay or Attack/Hold/Release envelope.
The time parameters "up" and "down" (or rise and fall) can be set manually and by control voltages (with polarizer type attenuators). The Up-CV input is normalized to the Down-CV input. Additionally there is the exp-CV socket controlling both parameters, which has a voltage characteristic of almost 1V/octave. The curve characteristics can be switched from linear to non-linear separately for each time constant; the characteristic of nonlinear settings can be set from exponential over linear to logarithmic with potentiometers. This makes it possible to set a certain punch of an envelope, for instance.
The END output generates a gate when the output signal drops below 20mV. Connecting this out with the trigger output makes the A-171-2 oscillate, therefore it can be used as an LFO or audio oscillator. You don´t need to patch, though - just activate the Cycle switch!
CV inputs for rise and fall (normalized), exp-CV input
Signal input, signal output, trigger input, end-of-cycle output
3U Eurorack module, 8 HP wide, 60 mm deep