Doepfer A-113 User Manual
doepfer
System A - 100
1. Introduction
Subharmonic Generator
A-113
A-113
Subharmonic Generator
1
Up
8.8.
Down
2
Up
8.8.
Down
3
Up
8.8.
Down
4
Up
8.8.
Down
Foot
Freq.
Ctr. 1
In
Attention ! The A-113 module requires an additional
+5V power supply with 100mA (e.g. the separate +5V
power supply or the +5V low-cost adapter)
Foot
Ctr. 2
Level
Out 1
Leve l
Out 2
Level
Out 3
Store
Level
Out 4
Preset
Mix
Out
Module A-113 (Subharmonic Generator) is an additional sound source that derives four independend
so-called Subharmonics from an incoming pulse signal. The module represents the sound generation
core of the
Sala (ref. chapter 6).
Subharmonic means in this context a sawtooth wave
whose frequency is derived from a master frequency.
The master frequency is divided by an integer 1...24 to
obtain the subharmonic. The subharmonics are available as 4 single outputs as well as mix output with
adjustable level for each subharmonic.
The integer
up/down buttons. The current divisors are displayed
with four 2-digit LED displays.
The combination of 4 divisors is called
mixtures form a preset. 50 presets can be stored and
called up within the module.
Two gate inputs are available to switch between the
4 mixtures within one preset (controlled by any gate
signals, e.g. from foot controllers).
Mixtur-Trautonium
divisor
for each subharmonic is set with
introduced by
mixture
Oskar
. 4
1
A-113
Subharmonic Generator
System A - 100
2. Basic principles
The Subharmonic Generator A-113 contains four times the following elements (see fig. 1)
• digital frequency divider (rectangle outputs) with
2-digit display and up/down buttons for divisor adjustment
• rectangle/sawtooth converter (with single output)
• attenuator controlling the amount (i.e. the ampli-
tude) of the subharmonic in the mix output
The incoming signal (preferably the rectangle ouput of
a VCO) is fed into the four frequency dividers. The
frequencies of the rectangle signals generated by the
frequency dividers are determined by the current divisors (1...24).
The rectangle outputs are converted to sawtooth waveforms by means of the rectangle/sawtooth converters.
doepfer
Fig. 1: Basic layout of the A-113
2
doepfer
System A - 100
Subharmonic Generator
A-113
Subharmonics
The
subharmonics
the frequency of the input signal.
The table in fig. 2 shows the frequencies and corresponding tone pitches of the resulting subharmonics
derived from an input signal with the tone pitch C
523,2 Hz).
Divisor Freq. [Hz]
1523,2C
2261,6C
3174,6F
4130,8C
5103,8As
687,3F
773,4D
865,4C
Fig. 2: Subharmonics of a signal with tone pitch C
result from
Note
5
4
3
3
2
2
2
2
integer division of
5
(i.e.
5
It becomes apparent that the subharmonics are equivalent to the tones of the
By way of contrast the
minor chord scale
harmonics
are equivalent to
.
the tones of the major chord scale. Harmonics are
integer multiples of the basic frequency (see fig. 3).
The undertone series (i.e. subharmonics) are the
mirror image of the overtone series (i.e. harmonics).
Factor Freq. [Hz]
165,4C
2130,8C
3196,0G
4261,6C
5329,6E
6392,0G
7466,1B
8523,2C
Fig. 3: Harmonics of a signal with tone pitch C
Note
2
3
3
4
4
4
4
5
2
3
A-113
H
Subharmonic Generator
The term "subharmonic" is not quite correct as
the A-113 outputs are sawtooth waveforms in
contrast to the sine waves used in the harmonics theory. A sawtooth wave has a marked
harmonic spectrum with odd and even overtones in contrast to the sine wave which is a
“pure” wave without overtones. For details concerning harmonic contents of different waveforms please refer to the A-110 or A-111
manual (VCO´s).
We wanted to use the same terms as Oscar
Sala in his Mixtur Trautonium and this is why
we call the outputs of the A-113 subharmonics
though they are sawtooth outputs.
System A - 100
Mixture
The combination of four subharmonics is called a
mixture. Four different mixtures ("00", "01", "10" und
"11") are available but only one mixture is active at a
time. The original Mixtur-Trautonium had only three
mixtures available but due to the binary structure of the
A-113 we introduced 4 mixtures.
doepfer
the volume foot controller are used to switch between
the 3 mixtures.
Preset
A preset consists of 4 mixtures with 4 divisors each
(see fig. 4). 50 presets can be stored and called up
within the A-113 module. The original MixturTrautonium had no presets available. Each mixture
had to be changed manually.
T1 T1 T1 T1
divisor
(display)
mixture
Fig. 4: Structure of a preset
T2 T2 T2 T2
T3 T3 T3 T3
T4 T4 T4 T4
"00" "01" "10" "11"
The active mixture is selected by the current state of
the two
Trautonium 2 foot switches mounted left and right of
4
gate control inputs
. In the original Mixtur-
doepfer
System A - 100
Subharmonic Generator
A-113
2. Overview
➃
➂
➁
➀
8.8
8.8
8.8
8.8
➅
➄
.
.
.
.
Divisor
Divisor
Divisor
Divisor
Store
Preset
A-113
Subharmonic Generator
Level
1
10
0
Level
2
10
0
Level
3
10
0
Level
4
10
0
SHG
Single
Out
Single
Out
Single
Out
Single
Out
Foot Ctr.
Foot Ctr.
Mix Out
In 1
In 2
Controls:
1 Display : displays the current divisor
Up
2
: button to increase the divisor
data
3 Down : same to decrease
Level : output level control (mix out-
4
➍
In
➊
➋
➌
➎
Preset
5
6 Store : preset store button
: preset selection button
In / Outputs:
! In : common audio input
Foot Ctr. 1
"
Foot Ctr. 2 : gate input 2 to switch bet-
§
Mix Out
%
$ Single Out : audio single output
put)
(rectangle input)
: gate input 1 to switch bet-
ween the mixtures
ween the mixtures
: audio mix output
5
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