The A-117 is a versatile digital niose generator. It has two parts: an „808 Sound Source“ whith a 6-oscillator output (cymbals) and a 2-oscillator output (cowbell) for percussive sounds known from an 808-style rhythm machine as well as a digital noise output.

The sound example here starts with the 6 oscillators output (through an A-132-3 VCA, controlled by a sequencer-triggered A-140 ADSR) and blends over to the 2 oscillators output (same patch). Quite a nice thing, if you like that kind of machines.

Then, we crossfade to the digital noise, which is  a kind of „Geiger-Counter“, here tempo-synced to the sequencer (i.e. the random clicks stay within the rhythm – just randomly switched on or off, which makes it quite usable in a musical context). Tempo / tuning of the digital noise can either be controlled manually or with an external clock source (sequencer, square LFO/VCO waveform). Later, the tempo is increased, until we have something that reminds of „normal“ white noise:

http://www.andreaskrebs.de/assets/media/A-117.mp3

Detailed information can be found on Doepfer’s Homepage:

http://www.doepfer.de/a117.htm

Andreas