ringmod~

A type of audio mixer combining two audio signals, and outputting their sum and difference. The frequencies found in the original signals are not passed through to the output. For example, if two sine waves (single frequency waveforms containing no overtones) are inputted, one with a frequency of 1000 Hz, and the second at 400 Hz, the ring modulator will output two frequencies: 600 Hz and 1400 Hz. With more complex waveforms (which contain many more overtone frequencies) ring modulators produce a clangorous, "metallic" result often used for special effects, in synth programming, and so on. One popular use has been to process vocals, which produces sci-fi sounding "robotic" voices. [sw]

version

v1.0: built 12/04/2007 with Pd v0.40-2 [pd][pdf]

interface

Input 1: the (mono) audio signal input
Input 2: the modulation frequency, it's got no real boundaries but typical values are presented in the image on top.
Input 3: a reset inlet. When this is banged, the modulating wave is reset to it's beginning. Look at the documentation of the waves block.

Output1: the ring-modulated output audio signal

Controls:
MIDI commands for choosing different oscillators for modulation. View the documentation of the waves block.

implementation

Digital ring modulation is nothing more than a multiplication of a signal with another signal. The modulating signals' frequency is very low when one wants to hear the modulating envelope. For ring modulation it's faster. The multiplication is an arbitrary scaling of the modulation frequency input and can be left away. The outlet is high pass filtered to forbid the lowest frequencies (inaudible 5Hz and less) to slip through.