Ring modulation is an audio effect performed by multiplying two audio signals, where one is typically a sine-wave or another simple waveform. It is referred to as "ring" modulation because the analog circuit of diodes originally used to implement this effect took the shape of a ring. Sound effects or audio effects are artificially created or enhanced sounds, or sound processes used to emphasize artistic or other content of movies, video games, music, or other media. ... A sine wave or sinusoid is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C is the vertical offset. ... An analog circuit (or analogue circuit) is an electric circuit that operates on analog signals. ... Types of diodes A diode can be thought of as the electronic version of a one-way valve. ...

Ring modulators are mostly used in synthesizers. They combine or heterodyne two waveforms, and output the sum and difference between the two. This process of ring modulation, also called amplitude modulation, produces a signal rich in overtones, suitable for producing bell-like or otherwise metallic sounds. Ring modulators were used by the BBC Radiophonic Workshop to produce the distinctive voice of the Daleks in the television series Doctor Who. A ring modulator effect is added to the guitar solo in the song Paranoid by Black Sabbath. Modern ring modulators are implemented using digital signal processing techniques by simply multiplying the time domain signals. A classic FM synthesizer, the Yamaha DX7. ... In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode mixer. ... Waveform quite literally means the shape and form of a signal, such as a wave moving across the surface of water, or the vibration of a plucked string. ... An overtone is a sinusoidal component of a waveform, of greater frequency than its fundamental frequency. ... The BBC Radiophonic Workshop, the sound special effects unit of the BBC was created in 1958 to produce sound effects for radio and was closed around 1996. ... The Daleks (pronounced DAH-lecks; IPA: ) are a fictional extraterrestrial race of mutants from the British science fiction television series Doctor Who. ... A television program is the content of television broadcasting. ... Main article: History of Doctor Who Doctor Who first appeared on BBC television on November 23, 1963. ... Clockwise starting from the left, Bill Ward, Tony Iommi, Geezer Butler, Ozzy Osbourne This article is about the British heavy metal band. ... Digital signal processing (DSP) is the study of signals in a digital representation and the processing methods of these signals. ... Time-domain is a term used to describe the analysis of mathematical functions, or real-life signals, with respect to time. ...

Multiplication in the time domain is the same as convolution in the frequency domain, so the output waveform contains the sum and difference of the input frequencies. Thus, in the basic case where two sine waves of frequencies f₁ and f₂ (f₂ > f₁) are multiplied, two new sine waves are created, with one at f₁ + f₂ and the other at f₂ − f₁. Two points to note are that firstly the two new waves are unlikely to be harmonically related and secondly that (in a well designed ring modulator) the original signals are not present. It is this that gives the ring modulator its unique tones. Time-domain is a term used to describe the analysis of mathematical functions, or real-life signals, with respect to time. ... This article is about the mathematical concept of convolution. ... Frequency domain is a term used to describe the analysis of mathematical functions with respect to frequency. ...

Interesting harmonics can be generated by carefully selecting and changing the frequency of the two input waveforms. If the signals are wideband, it is likely that the circular convolution will cause aliasing distortion, so it is common to oversample the operation or filter the signals prior to ring modulation. In acoustics and telecommunication, the harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Waveform quite literally means the shape and form of a signal, such as a wave moving across the surface of water, or the vibration of a plucked string. ... Wideband is a relative term used to describe a wide range of frequencies in a spectrum. ... In statistics, signal processing, and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. ... In information theory, oversampling is the process of sampling a signal with a sampling frequency higher than the nyquist frequency. ...

On the C64 SID chip, ring modulation multiplies a triangle wave with a square wave. A ring modulator module was a common feature on early modular Moog synthesizers. The ring modulator went out of fashion with the advent of all-in-one synthesizers and sampled-based synthesizers, but has returned as a feature in digital modelling and software synthesizers. Close_up of C64 Commodore 64 (C64, CBM 64) was a popular home computer of the 1980s. ... MOS Technology SIDs: The right image shows a 6581 from MOS Technology, at the time they were known as the Commodore Semiconductor Group (CSG) and the left image shows an 8580 from MOS Technology. ... A triangle wave is a waveform named for its triangular shape. ... A square wave is a kind of basic waveform. ... Bob Moog Dr Robert A. Moog (born May 23, 1934) is the inventor of the Moog synthesizer. ... // Software synthesizers A software synthesizer or virtual instrument is a computer program for digital audio generation. ...

See also: Heterodyne In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode mixer. ...

External link

• Harmony Central: Effects Explained: Ring Modulation by Scott Lehman