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System A - 100
1. Introduction
Dual Ring Modulator A-114
A-114
RING MOD.
X IN
Y IN
X • Y OUT
X IN
Y IN
X • Y OUT
Module A-114 (Dual Ring Modulator) contains two
separate
ring modulators
.
A ring modulator outputs the product (Multiplication X •
Y) of the signals at inputs X and Y. It’s similar to a
VCA, but whereas a VCA only responds to positive
voltages at the inputs (2-quadrant multiplication), the
ring modulator responds to both positive and negative
voltages (4-quadrant multiplication).
The ring modulator thus provides a refinement of
amplitude modulation (AM). Ordinary amplitude modulation will output the original carrier frequency f
well as the two side bands (f
- fM, fC + fM) for each of
C
C
as
the spectral components of the carrier and modulation
signals - but ring modulation cancels out the carrier
frequencies, and just lets the side-bands pass to the
output (see Fig. 1).
A ring modulator is used for the production of bell-like
sounds, alien voices, or just to produce new timbres.
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A-114
Dual Ring Modulator
System A - 100
2. Dual Ring Modulator - Overview
A-114
RING MOD.
➊
X IN
In / Outputs:
! X In : Signal input
"
X*Y Out : Output
§
: Signal input
Y In
doepfer
➋
➌
2
Y IN
X • Y
OUT
RING MOD.
X IN
Y IN
X • Y
OUT
doepfer
System A - 100
Dual Ring Modulator A-114
3. In / Outputs
! X In • " Y In
Sockets ! and " are the
signal inputs for the
Patch the signals you would like to ring modulate into
these sockets.
The inputs need to have AC signals - so you should
use audio signals, not control voltages. For control
voltages, use a VCA.
§ X*Y Out
Socket § is the ring modulator Output.
A-114.
4. User examples
Basic ring modulation
Fig. 1 shows a basic form of ring modulation using two
sine waves. This patch can provide bell- and vibes -
like sounds.
A-114
RING MO D.
f = 440 Hz
C
f = 77.7 Hz
M
Fig. 1: Ring modulation with two sine waves
X IN
Y IN
X • Y OUT
f + f = 517.7 Hz
C
f + f = 362.3 Hz
CMM
fC - fM = 362.3 Hz
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A-114
Dual Ring Modulator
System A - 100
doepfer
Ring modulation of audio signals
A ring modulator is very good at doing weird things to
audio signals
The example at Fig. 2 shows an audio signal (input via
module A-119 "Ext. In") ring modulated with a sine
wave. The spectrum at the output contains the sum
and difference of the frequency of the sine wave with
every single one of the components of the audio
signal’s sound spectrum.
ext .
Audio In
: Ring modulation of an external audio signal.
Fig. 2
(for instance, voices, strings, sax).
A-114
VCO
Audio Out
A-119
Env. Out
RI N G M O D.
X IN
Y IN
X • Y OUT
VCA
In this patch, the A-119 performs two functions.
On the one hand, it’s bringing the level of the external
signal up to the A-100’s operating level (round about 5
).
V
SS
On the other hand, it’s also sending the envelope
follower output (the envelope generated by the external audio signal) to a VCA. This is necessary because
the ring modulator doesn’t completely shut off when
there’s 0V input. The VCO is still just audible, at
approximately -50 to -60dB, even when there’s no
external audio signal. The VCA gates it completely.
P Experiment with this set-up, for instance by
replacing the sine wave with other waveforms (eg. sawtooth, square wave, etc.)
The waveform you use can itself also be
modulated (for instance by PWM, AM, FM,
or audio signal).
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doepfer
System A - 100
Dual Ring Modulator A-114
“Glissando ring modulation”
The patch in Fig. 3. produces some interesting
sounds. Input two VCOs set to an exact harmonic
interval (eg. a fifth or octave) into the ring modulator.
Send the pitch CV direct to the first VCO, but run the
second oscillator’s CV through the upper section of the
slew limiter (A-170) first.
Whenever the pitch CV changes, the ring modulation
causes gradual changes in the sound spectrum.
ADSR
Gat e
A-170
CV
VCO 1
VCO 2
A-114
RI N G M O D.
X IN
Y IN
X • Y OU T
VCA
H Use the upper part of the A-170 for this,
because the diode offset in the lower part wlll
put the VCO out of tune.
: “Glissando ring modulation”
Fig. 3
5
A-114
Dual Ring Modulator
5. Patch-Sheet
System A - 100
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The following diagrams of the module can help
you recall your own Patches. They’re designed so
that a complete 19” rack of modules will fit onto an
A4 sheet of paper.
Photocopy this page, and cut out the pictures of
this and your other modules. You can then stick
them onto another piece of paper, and create a
diagram of your own system.
Make multiple copies of your composite diagram,
and use them for remembering good patches and
set-ups.
P • Draw in patchleads with colored
pens.
A-114
RING MOD.
X IN
Y IN
X • Y
OUT
X IN
Y IN
X • Y
OUT
A-114
RING MOD.
X IN
Y IN
X • Y
OUT
X IN
Y IN
X • Y
OUT
A-114
RING MOD.
X IN
Y IN
X • Y
OUT
X IN
Y IN
X • Y
OUT
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