Ring Modulation is the coolest sounding audio effect ever discovered, and it is suprisingly easy to implement in any electronic music setup. Synths, Guitars and Percussion all sound cool when put through a ring mod and the range of bizzare and twisted sounds that can be produced is truly limitless.

If you are a serious musician, then you will want to get your hands on one, or even better yet -- build your own! (very easy, as we shall see...)

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.

Here's an example where two sine wave oscillators were used, one remains at a fixed pitch while the other is swept from low to high back to low frequency: RealAudio G2


Build Your Own!!!

This simple schematic shows how to build a passive ringmod using 4 diodes and two small-signal centre tapped transformers. I've gotten best results using MOUSER TM018 transformers, and germanium diodes. The only other things you need are 3 1/4" phono jacks and a suitable case. The circuit reauires no batteries, although you wont get any sound out unless you have both IN's playing. (There is a slight signal leakage when one of the inputs is playing and the other is silent)

This is my first ringmod, built in an old plastic fishing tackle case with the three jacks conveniently located on the top of the unit. Note the stylish red over black.

Interestingly enough, any of the jacks can be used as the carrier, modulator, or output... It doesn't seem to matter which is which for this circuit! Now let's look at some interesting applications of the ringmod...


Applications

Using two synths, plug the respective outputs into the carrier and modulator inputs of the ringmod, and then plug the ringmod into your mixing board. Now play different notes on each synth, and experiment with mixing different pitches and waveforms. Try running a TB-303 with a sine wave on another synth, controlled with the pitchbend wheel. Instant coolness!

Using one synth fed into the ringmodulator, with the signal from the synth cloned and sent through a digital delay. Now when you play a sequence of notes, the ones you have just played will come back to 'haunt' you, and modulate your current note. This works well when the delay is synced to the BPM of your music, and is very spooky with pitchbender.