Doepfer A-113 Subharmonic Generator

A sound source for generating subharmonic minor-chords like in the Trautonium. It contains four parallel frequency dividers with factor 1-24, which derive fixed partial frequencies - the so called subharmonics - out of the frequency of an external  master VCO. The module has 50 memory banks each for 4 mixtures, i.e. mixes of partial frequencies.

The term subharmonics was introduced by Oskar Sala in connection with his so-called Mixtur-Trautonium. A subharmonic means in this context a sawtooth wave (German: Kippschwinger) whose frequency is derived from a master frequency and the master frequency is an integer multiple in the range of 1 to 24 of the subharmonic - in other words: the master frequency is divided by an integer 1 to 24 to obtain the subharmonic.
Pay attention that the output waveform of a subharmonic is sawtooth (as also used in the original Trautonium) and not sine. The term subharmonics is somewhat misleading. The master frequency comes e.g. from an oscillator to the frequency input of the A-113. The frequency dividers of the 4 subharmonics is adjusted with up/down buttons as displayed with 2 character LED displays. The subharmonics are available as single outputs and as mix output with adjustable levels for the subharmonics.

Two gate type control inputs enable to select between 4 different mixtures, i.e. 4 different settings of the frequency dividers. In the original Trautonium these are controlled by foot switches to switch between 3 mixtures while playing (the original Trautonium has only 3 mixtures available but with the 2 gate inputs of the A-113 four different settings can be adressed).

Additionally the A-113 features a mixture memory with 50 presets. Each preset consists of 4 mixtures that can be selected with the gate inputs, each mixture contains the values of the 4 frequency dividers.