|
What Is Ring Modulation?
First a basic definition:
| quote: | A ring modulator is a simple device that can be used to create unusual sounds from an instruments output. It effectively takes two signals (each with some frequency), and produces a signal containing the sum and differences of those frequencies. These frequencies will typically be non-harmonic, so the ring modulator can create some very dissonant sounds.
...Modulation means that we are changing some aspect of a tone, such as its amplitude, frequency, or phase. In the ring modulator, we are using amplitude modulation (more specifically, suppressed-carrier modulation) which is implemented simply by multiplying two signals.
http://www.harmony-central.com/Effe...ing_Modulation/ |
In the digital domain, "multiplying two signals" basically means taking a sample of each signal and multiplying together the instantaneous amplitude of the two signals within the time frame of that sample.
One way to think of ring modulation is as modulation of an audio signal with another audio rate (rather than "control rate") signal. "Audio rate," in the context of signals, refers to a signal that is fast enough to be audible as a "tone" by the human ear, generally from 20 Hz (wave cycles per second) to 20 kHz. "Control rate" refers to any signal slower than this; signals at control rate speed are used to control things like LFOs, which give you a "wavering" or "wobbling" effect in pitch, amplitude, or other characteristics of a synth sound.
It might sound a bit complicated, but the gist is just that amplitude modulation (like you can get with any old LFO) and ring modulation are part of the same continuum. When you are "ring-modulating" something, you are basically just amplitude-modulating it really fast.
So what does a digital implementation of ring modulation look like? Here is one simple example:
Obviously there is a lot more you could do here. You could, for example, modulate the amplitude of the modulating sine wave, which could give you either a "serial" ring modulation or a ring modulation plus wavering amplitude. Or you could split the signal from the sample and run it through multiple ring modulators, giving you "parallel" ring modulation. But here is an example using the simple patch above, ring modulating a dialogue sample with a sine wave (it's a bit quiet, sorry about that):
http://www.youtube.com/watch?v=rWi8EbMlEhM
If you've seen the movie A Scanner Darkly, you should recognize the effect on the vocal as the sine's frequency starts to shade from control rate into audio rate.
Ring modulation can also be fun as an effect on instruments or drum loops. If you have any tips or questions regarding ring modulation, feel free to post them in here.
Last edited by MrJiveBoJingles on Nov-24-2009 at 22:05
|
