modDemix
Limited WARRANTY:
Make Noise warrants this product to be free of defects in materials or construction for a period of one year
from the date of purchase (proof of purchase/invoice required).
Malfunction resulting from wrong power supply voltages, backwards power cable connection, abuse of the
product or any other causes determined by Make Noise to be the fault of the user are not covered by this
warranty, and normal service rates will apply.
During the warranty period, any defective products will be repaired or replaced, at the option of Make Noise,
on a return-to-Make Noise basis, with the customer paying the transit cost to Make Noise. Please contact
Make Noise for Return To Manufacturer Authorization.
Make Noise implies and accepts no responsibility for harm to person orapparatus caused through operation
of this product.
Please contact technical@makenoisemusic.com with any questions, needs & comments, otherwise...
go MAKE NOISE.
http://www.makenoisemusic.com
Thanx to Surachai for his help in beta testing, and to the electronic music pioneers who reclaimed radio
communications tech for musical purposes.
Installation:
The Make Noise modDemix is an analog electronic signal processor requiring 28mA of
+/-12V regulated power and properly formatted distribution receptacle to operate. It is
designed for use within the euro format modular synthesizer system.
Visit http://www.doepfer.de/a100_man/a100t_e.htm for the details of this format.
To install, find 6HP of space in your euro-rack synthesizer system, plug the 16pin power
cable into the euro-rack style power distribution board, minding the polarity so that the RED
stripe on the cable is oriented to the NEGATIVE12 volt supply line. This is USUALLY at the
bottom.
Please refer to your case manufacturers’ specifications for location of the negative supply.
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modDemix Panel Controls
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Signal 1 IN: signal to be processed.
Carrier/ CV 1 IN: determines amplitude & phase of Signal 1 IN. Normalled to Carrier/ CV.
Signal 1 OUT.
Signal 2 IN: signal to be processed. Normalled to Signal 1 OUT.
Signal 2 OUT.
SUM OUT: mix of Signal 1 OUT, Signal 2 OUT & AUX. IN v
Carrier/ CV 1 Strength: attenuator for Carrier/ CV IN.
AUXiliary INput to Summing stage: chain multiple units for larger mixes.
Carrier/ CV 2 IN: determines amplitude & phase of Signal 2 IN. Normalled to Signal 2 IN.
Carrier/ CV 2 Strength: attenuator for Carrier/ CV IN.
Getting to Know modDemix:
Standard AM, Balanced Modulation, Signal Multiplication, Frequency Mixing, Single Sideband, Double Sideband and even XOR (as in Boolean logic) have all been used to implement “Ring Modulators” for musical
purposes in the last 50 years. In a way, Ring Modulation has become a catch-all term for music technology
that results in a complex, clangorous, modulated sound.
The modDemix consist of 2 identical direct coupled circuits that may be used together or independently to
process audio or control signals by means of amplitude modulation and the many derivatives of AM such as
double/ single-sideband, voltage controlled amplification/ attenuation, voltage controlled polarization or
multiplication and of course, ring modulation. The modDemix is a specialized amplitude modulation circuit
that could be thought of as a “Thru-Zero VCA,” meaning that in addition to the AM, when the Carrier signal
(called Carrier/ CV) changes phase, the resulting signal’s phase will flip as well. What makes the modDemix
unique when compared to other Balanced Modulators, is that because it is Direct Coupled, it will perform
wonderfully both as an Audio Rate modulator to implement Ring-Modulation, and as a Control Rate modulator to implement multiplication of control voltages. Additionally, the circuit used within the modDemix will, with
ease, turn OFF around zero volts at the Carrier/ CV INput, a characteristic that makes the circuit behave very
well as a VCA. Both of the circuits feed a SUMming stage, which thus allows the module to be used as a
voltage controlled mixer. An AUXiliary IN allows for the chaining of multiple modDemix units to create larger
mixes. An attenuator at the Carrier/ Control INput allows for setting the Strength or level of the incoming
signal. When performing ring modulation, adjusting the strength of the Carrier will alter the integrity of the
resulting modulated and/ or demodulated signal, thus affecting the timbre as well as the amplitude. When
using the modDemix in most other ways, the Strength control will be directly related to the amplitude of the
resulting signal.
To better understand the concepts of AM and it’s derivatives, patch a DC offset from CH. 2 of Make Noise
MATHS (using associated panel control to set the level) to Signal IN of modDemix. Patch a DC offset from
CH. 3 of MATHS to Carrier/ CV IN of the modDemix. Set modDemix Strength to full CW. Take output from
Signal OUT on modDemix, patch to an Oscilloscope, DVM for visual feedback, or patch to the 1V/ Octave
input on a VCO and listen to the results. Setting a +3V offset at the Signal in, and +5V offset at Carrier/ CV
IN would result in a +3V Signal OUT. A +3V Signal IN and a -5V signal OUT would result in a -3V Signal
OUT. Please note that because it is designed for musical purposes, the modDemix Carrier/ CV IN is scaled
so as to operate with voltages typical of the euro format modular synthesizer, which is why it takes +5V at
Carrier to generate the +3V Program Signal at the OUT.
Now replace the DC Offset signal patched to the Signal IN on modDemix, with that of a VCO, preferably a
SINE waveform, at audio rate. Leave MATHS CH. 3 patched to Carrier/ CV IN. Patch modDemix Signal
OUT to your monitoring system. Adjust MATHS CH. 3 from full CCW to full CW and observe the change in
amplitude and phase. Listen for the point at which the sound goes “Thru-Zero.”
Now remove the DC Offset signal patched to the Carrier/ CV IN, and replace with the MATHS SUM OUT. Be
sure to set MATHS CH. 2 and 3 to 50% (NULL). Leave the VCO patched to modDemix Signal IN. Initiate the
CYCLE behavior on CH. 1 MATHS. Adjust the MATHS CH. 1 attenuvertor to around 3 o’ Clock. Observe
standard Amplitude Modulation. Listen for the presence of Sidebands, and “Carrier Feed-Through.” Experiment with the rate of MATHS cycling, and the Strength control.
Using same patch as above, add a negative offset to the Cycling CH. 1 of MATHS, by adjusting CH. 2 panel
control to full CCW. Observe Balanced Modulation. Observe the low amount of Carrier Feed-Thorough.
Depending upon the Negative Offset added, the Carrier all but vanishes, making the resulting Sidebands
more audible. This is the sound most commonly associated with Ring Modulation. Experiment with different
amounts of negative offset, which could said to control the Depth of the Ring Modulation. Also experiment
with different Carrier Strengths and observe the resulting timbre and amplitude changes.
Return the CH. 2 panel control to 50% (NULL). Set CH. 4 of MATHS for a slow Rise and Fall, and set the
corresponding attenuvertor to about 10 o’ Clock. Initiate the cycling behavior at CH. 4. Observe voltage
control over Ring Modulation Depth. Experiment with combinations of DC Offsets (MATHS CH. 2), triggered
or Cycling Offsets (CH. 4 MATHS) added to the Carrier (MATHS CH. 1). Patch a sequencer from Pressure
Points to CH. 3 MATHS and add that to the Carrier (as generated by CH. 1 MATHS). Experiment.
Patch Ideas:
VCA
Patch signal to be processed (audio or control) to Signal IN. Patch uni-polar control signal such as Envelope,
LFO, Pressure Points CV or gates, to the corresponding Carrier/ CV IN. Take output from Signal OUT. Use
Strength to set the level of the resulting signal. If the Carrier/ CV Signal is oscillating at audio rate, you will
achieve. Amplitude Modulation. Like Ring-Modulation, AM produces audible sidebands. The main difference
is that the Carrier signal is not suppressed, so along with those sidebands, you hear the Carrier. Musically
speaking, this sound is quite useful when a complex timbre is desired, but not at the loss of a strong root
note.
Balanced Modulation, aka “Ring Modulation,” aka Frequency Mixing
Patch audio signal to be processed to Signal IN. This will be the Program. The Carrier signal should be a
bi-polar Audio Rate Signal such as a VCO (so it needs to swing from positive to negative). The resulting
signal, at Signal OUT, will be the result of the Signal IN having both amplitude and phase directly related to
that of the Carrier/ CV IN. To achieve single or double sideband, the balanced modulator is followed by filters
tuned so as to eliminate all but one or two sidebands. Obviously, this is not entirely possible within the
current synthesizer system, since it requires filters designed exclusively for the job, still many interesting
timbres may be heard by using two band pass filters in parallel after the modDemix, for “Stereo-QuasiDouble-Sideband.” Modulating the filter cutoff will animate the sidebands.
Control Signal Multiplication or Voltage Controlled Polarization
Same as Balanced Modulator patch, only both the Signal IN and Carrier IN are both Control Signals as
opposed to Audio Signals. Use the signal patched to Carrier/ CV IN to multiply the Signal patched to Signal
IN. Take output from Signal OUT. Remember the “Thru-Zero VCA” concept when trying to understand how to
use this patch.
Voltage Controlled Mixer
Use the VCA patch, apply control signals such as the CV outs from Pressure Points, to the Carrier/ CV Ins of
both channels. Take output from SUM out. Create larger mixes by chaining several modDemix together. To
do this patch the SUM out from one into the Aux. IN on the next one in the chain, and so on, to create 2, 4, 6,
8 channel mixes.
Mod-Demod
To ease the patching of modDemod effects, Signal 2 IN is normalled to Signal 1 OUT, thus connecting the two
circuits in series. Carrier/ CV 1 IN is normalled to Carrier CV 2 IN, so that in patching the desired Carrier Signal to
Carrier/ CV 2 IN, the modulation and demodulation processes share a single Carrier Signal. Patch Signal to be
processed to Signal 1 IN. Patch Carrier to Carrier/ CV 2 IN. Take output from Signal 2 OUT. The variation from circuit to
circuit will introduce demodulation errors that sound as distortions. Using the Strength controls, it is possible to
introduce more errors and to greatly reduce the integrity of the resulting signal. A nice variation on this patch uses a
pair of independent Carrier VCOs, which are tuned to same frequency, but not synced. Variations in waveshape and
Phase inaccuracies between the two VCOs will introduce more demodulation errors and distortions.
Octave UP
To ease the patching of octave UP effects. Carrier/ CV 2 IN is normalled to Signal 2 IN. Patch your signal to be
processed to Signal 2 IN. Patch the Signal 2 OUT into Signal 1 IN, take the output from SUM OUT. Use the Strength
controls to adjust timbre and blend of octaves.
DPO Supersaw
This patch uses voltage controlled inversion to derive a sawtooth wave from the DPO’s Final Output. Mixing it with
the VCOA Sawtooth produces a slightly unconventional, but nonetheless classic, supersaw.
Turn off all modulation to Final output parameters and the MOD BUS. Adjust FOLD panel control to ~9:00 so the
output is full amplitude but with no folds yet. Adjust ANGLE panel control to 12:00, listening for the fullest sound
available. Adjust SHAPE panel control full CW (100%) to “glitched triangle”.
DPO Final OUT -> ModDemix Ch1 Input
DPO Square -> ModDemix Ch1 Carrier/Mod Input
ModDemix Ch1 OUTput -> Mixer
DPO Sawtooth -> Mixer
Mix and detune the two sawtooths to taste. The sawtooth derived from the FINAL output will be one octave above
its original pitch, and it will also contain a slight “spike” at its peaks and troughs (because of its origins as a “glitched”
triangle, as well as varying slightly in amplitude every other period (because of the DC offset in the DPO’s square
wave). Combined with the unusual sawtooth shape on VCOA, which has a stronger-than-usual fundamental, this
patch produces a supersaw with character!
Voltage Controlled Crossfading and Panning with ModDemix and MATHS
Crossfading
Send two signals of your choice to the ModDemix Ch1 and Ch2 INputs. Select a positive-going Control Signal such
as a MATHS/Function envelope or a sequence from Rene.
Set up a Voltage Mirror with MATHS
(Apply Control Signal to be mirrored to CH. 2 Signal IN. Set CH. 2 Attenuvertor to Full CCW. With nothing inserted at
CH. 3 Signal IN (so as to generate an offset), set CH. 3 Attenuvertor to full CW. Take output from SUM OUT.) Note that
if your Control Signal is from Ch1 or 4 of the same MATHS, use the variable (rather than Unity) Output to avoid
having the original signal show up in the SUM again.
Using a multiple, patch the original Control Signal to ModDemix Ch1 Carrier/CV IN, and the mirrored version from
MATHS SUM to Ch2 Carrier/CV IN. Monitor ModDemix SUM Out. Some adjustment of the MATHS Ch2 and Ch3 panel
controls may be necessary to fine-tune the crossfader.
Panning
For panning, patch identically to the crossfading patch, except instead of two signals, mult the same signal to Ch1
and Ch2 on the ModDemix. Instead of monitoring the SUM Output, send the Ch1 and Ch2 outputs to Left and Right
inputs on your monitor, or to whatever further signal processing stages you prefer.