Author: Roland Kuit
Like other components of an electronic studio, the Ring Modulator comes out a different field. This device made it possible to have more telephones on one line. It works with a carrier signal and a modulator (equalized modulator or carrier suppression modulator). The term 'Ringmodulator' is the most common name in sound synthesis, and comes from the original analog method for creating this effect: a ring with four paired diodes accompanied by precision transformers. Both the Ring- and Amplitude modulator modules are very similar. The only difference is that there is no carrier signal present at the output of the Ring Modulator. This can therefore create special application for signal processing as we will see. There is no distinction between the two input signals on the Ring Modulator: they are both carrier and modulator. With Amplitude Modulation, there is a distinction as we will see as well.
So, let's look at some examples.
While Nord Modular users have all the knobs available, some of these examples require that Micro users use the knob floater.
First, you hear both signals, carrier and modulator. This is Amplitude Modulation. Turn Knob 4 and you will hear the carrier signal disappear. Now it is Ring Modulation. Turn knob 4 back. When you turn the knobs 2 and 3, you will notice that the 'sidebands' change. Experiment with different frequency's of the Oscillators and knob 4. Notice , there is no difference which signal is carrier or modulator.
Like the real thing, the Modular has a leaky Ring Modulator. This means that it's letting through sound, when there's no constant value of +1 or more on the modulator input.
You see only one signal present at the input of the Ring Modulator. And yes, you hear a sinewave. Now, connect a cable from the 'voltage processor' (constant module) to the Modulation depth input of the Ring Modulator and away is the unwanted breakthrough of the sinewave sound.
When you add and subtract two signals in the Ring Modulator, the outcome signals are called sidebands.
If you now turn Knob 2 you will hear the sound one octave higher. This is because since both the carrier and the modulator are at the same frequency, X + X = 2X which gives us one sideband in which the original sound, being doubled, is raised by one octave; and another sideband in which, since X - X = 0, the original sound is left unchanged. When the carrier signal and modulator signal have the same frequency, it becomes an octavider:
The Ring Modulator will add and subtract the frequency's of the carrier- and modulator signal. In this case: carrier signal 200 Hz and Modulator 100 Hz. will result in an outcome of 100 Hz. and 300 Hz. Turn knob 3 and hear the 300 Hz. fading in and out on the Lfo's frequency rate.
A majeur fifth as side band:
Turning knob 3 will cause the majeur fifth above the octave fading in and out. Because 400 Hz and 600 Hz create a side band of 200Hz. And 1000Hz.
To create a perfect fifth above the octave:
The sum and the difference are 440 and 1320, which is exactly the interval we require.
The most known sounds produced by the Ring Modulator are bell/metallic sounds. For this we need different frequency settings of the Oscillators, creating side bands on each side of the carrier wave and the resulting ring modulation wave phase-shifts 180 degrees every half modulator period.
Ring Modulation and metallic sounds:
Play with different frequency settings (knobs 2 and 3) for different timbres. Knobs 13 and 14 shifts the carrier and modulator's sinewave to a triangular wave. Now things become more interesting, because sinewaves doesn't have harmonics and the triangular waves have harmonics which will create sidebands as well.
The Ring Modulator module not only affects the pitch and timbre of sounds, it can also be used for all kinds of amplitude effects like echoes, gating, tremolos, etc.
The Ring Modulator as an echo creator
To create an echo you must understand that if there's no signal present at one of the inputs of the RM, there's no sound (except the unwanted breakthrough, see above). In this gater patch a triggered Envelope Generator will say 'on/off'. You can easily change the Envelope Generator by an external signal like piano or drums (Audio In Module) to 'trigger' one of the RM inputs.
The echo:
You hear a sustaining carrier signal, but if you connect the Mod.-Env's modulation out to the Carrier-Env modulation in, this problem is solved.
Somewhat more complex timbral examples:
Wrapped sinewaves
In the next patch we add signals with a more harmonic content. From sine waves to more complex waves.
With knobs 3 and 6, you can add more timbral complexity.
The Ring Modulators and filters:
In this example the two Oscillators are cross modulated. And the Modulator's signal is first filtered before entering the Ring Modulator. Now you can play with this harmonic content and the Ring Modulator will react on that.
Filtered Ring Modulator Feedback:
Carrier and Ring Modulator's output are both filtered and then fed back to the Ring Modulators Mod input. The other Oscillator (called 'Harmonics' in this patch) is modulating the filter from its output. Changing its frequency will result is a different timbral feedback.
Coloring Noise with the Ring Modulator:
In electronic music, there is not only spoken of Pink- or White Noise. But also about Brown- or Yellow Noise. This is the way you can produce another noise color spectrum.
More control by the Ring Modulator:
Spectral and panorama control.
Colored echo with the Ring Modulator:
In this case the Sample and Hold (see Sample & Hold workshop) is determining the amount of modulation between Ring- and Amplitude modulation. NB. This patch has to be connected to an external (midi) clock, or Int Clock of the Nord Modular.
Pitch control by Ring Modulation:
The LFO's pulse output will cause a jump in the tonal pattern created by the Pattern Generator and key quantizer.
Other timbral Ring Modulation:
Putting a level multiplier between the source and the Ring Modulator gives more 'fine' control (knob 6) .
Because of the Envelope Modulation on the Filter and the LFO Modulation on the Ring Modulator you can get sort of fading effects.
Creating subtle tremolos. Knob 3 for timbre, knob 3 for tremolo setting.
Play with filter settings and discover new timbres.
In this case Phase Modulated Oscillators are used.
But here, what happens if we use Low Pass Filters, instead of Band Reject Filters.
Very nice 'ringy' sounds are produced. And for the last example, see what happens with more extraordinary filtering.
Shift the Oscillator's pitch up with knob 2.
Attachment:
And thanks to Rob Hordijk:
Again, experiment with Audio In signals as well.
This concludes the Ring- and Amplitude Modulation examples.
I hope you will have a lot of fun with them. And much of my gratitude towards Kofi Busha for helping me out in this text.
