Web Sources

Frequency Chart


Good Source for different types of Ring Modulation/Amplitude Modulation (good visuals)


Amplitude Modulation

Guitar players will be familiar with the tremelo pedal, which rhythmicly fades the signal from the guitar in and out using a low frequency sine wave. Ring Modulation is just a form of tremelo except that the frequency of the VOLUME change is up in the audible range of frequencies. Normally two signals are simply ADDED together, such as in a mixing board. But in ring modulation, the amplitude of a carrier signal (X) is changed by the amplitude of the modulator signal (y) so that the two signals are actually MULTIPLIED together. This produces sideband frequencies that are the sum and difference of the frequencies present in the two signals.

FM modulation synthesis




Sound On Sound article on John Chowning and Frequency Modulation


Mix article on John Chowning -the creator of FM synthesis


Paul Lansky mp3 page


Paul Lansky "fun fact"

The Radiohead song "Idioteque," from its 2000 album Kid A, features a prominent sample from Lansky's computer tape piece "Mild und Leise" (1973), which itself interpolates Richard Wagner's "Tristan und Isolde"s opening motif. The sample, four looping chords taken from a few seconds of Lansky's piece, provides the entire harmony for the song. Lansky has written an essay about Radiohead that appears in The Music and Art of Radiohead, as well as online.

Paul Lansky interview


Ring Modulation

This instrument alters (modulates) the amplitude of one waveform (the carrier) by the sample values of a second (the modulator). Ring modulation is a simple multiplication of one waveform amplitude values by another. In ring modulation the modulator output is applied directly to the input of the carrier, without any DC offset to remove negative values as done in ‘classic’ ring modulation.

Ring modulation creates a somewhat unpredictable sound, often clangourous, because neither the frequency of the carrier or modulator appear in the final output, instead sidebands (overtones) at the sum and difference frequencies appear. In this example sine waves are used. You can imagine that when more complex sounds are used the resulting timbre is even more complex.

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