At first, people employed the ring modulator for analog telephony. Specifically, they used it for frequency-division multiplexing. Its target was to carry a variety of voice signals over phone cables. Since this start, ring modulators were part of voice inversions, radio transceivers, and several electronic music effects.
Ring Modulator: Its Context
Ring modulators began to gain popularity with the use of diodes. The Melo-chord was one of the first synthesizers to use this effect. After the Melo-chord became popular, Harald Bord, its creator, designed a stand-alone ring modulator. This new modulator has been part of many synthesizers since then. Buchla, Yamaha, EMS, and Oberheim, just to mention a few, began using these modulators in all their synths. Nowadays, practically all analog and digital synthesizers include one.
The Sound
The sound of the ring modulator is unique and it mimics a metallic or robotic sound. However, this modulator offers overtones that tend to be inharmonic—it’s part of its essence. The resulting effect is quite useful for sounding out tones and for music that doesn’t seem to have a particular tone center. The carrier signal and the input signal multiply, and, as a consequence, the effect changes. When the frequency drops at a level that becomes imperceptible to the human ear, it transforms into tremolo effect.
The ring modulation process generates a signal with many partials. When this happens, neither the carrier nor the incoming signal is prominent in the outputs. On the one hand, oscillators, whose frequencies are harmonically related and ring-modulated against each other, generate sounds that are essential to the harmonic partials of the notes. Regardless, they involve a very mismatched spectral makeup. On the other, when the oscillator’s frequencies are not harmonically related, the ring modulator generates an inharmonic effect. This effect mimics the metallic sound of a bell.
Ring Modulator: How It Works
A ring modulator has an input stage, an output stage, and a ring of four diodes. A carrier signal impulses these diodes. In addition, the input and output stages usually involve transformers with center taps that directed towards the diode ring. All the diodes in a ring modulator face in the same direction.
Ring modulators are bidirectional, which means that you can reverse the signal. This process allows the the same carrier to be used as a modulator or as a demodulator.
