Module A-119 is used to integrate external audio signals into the system A-100, and includes the components pre-amplifiers, envelope follower and a comparator. The preamplifier has two inputs: the unbalanced input with a gain factor of 0 ... 20 is mainly used for line-level signals, while the balanced input has a gain factor of 0 ... 500 for the integration of low-level signals (microphone , Electric guitar).
The envelope follower generates an envelope at its output, corresponding to the signal profile of the external audio signal. The comparator generates a gate signal corresponding to the level of an adjustable trigger threshold. Three LEDs are used to control the amplification (overdrive), the envelope and the gate signal.