A Simple Guide to Modulation: Ring Mod

Welcome back to A Simple Guide to Modulation, Sweetwater’s four-part series examining common modulation sources used for synthesizer sound design. So far in the series, we’ve discussed LFOs, envelope generators, and sample & hold. Now, we’ve arrived at our final modulator — ring modulation (ring mod). Ring mod differs from the previous modulators in that it doesn’t modulate parameters such as pitch, filter cutoff, pulse width, etc. Rather, ring mod is an amplitude-based sound-sculpting tool, which is used to create brash, metallic sounds. When pushed to the extreme, ring mod can be dissonant and harsh, and you may find it challenging to employ in a musical context. However, with the right settings, ring mod can create awesome textural patches that add excitement to your sonic creations. In this article, we’ll build four sounds using ring mod as our primary sound-design tool; but, before we dig into that, let’s first answer the question, “How does ring modulation work?”

How Does Ring Modulation Work?

For years, I thought the name “ring modulation” referred to the ringing tones that the effect produced. But, on my personal quest to wrap my mind around synthesis, I quickly discovered that it, in fact, refers to the ring-like shape of the diode circuit used to create a ring modulator. It’s just a happy coincidence that this diode ring also happens to create ringing, metallic sounds!

So, what is ring mod? Essentially, it’s an audio mixer that combines two signals and outputs their sum and difference while subtracting the original frequencies. As an example, if you send one 100Hz sine wave and one 400Hz sine wave to a ring mod, then it will output two frequencies: the difference signal of 300Hz (400 minus 100) and the sum signal of 500Hz (400 plus 100). When you apply ring mod to more harmonically rich waveforms, such as sawtooth or pulse waves, it generates clangorous sounds due to the shifting and often discordant harmonic relationships between frequencies.

Ring mod has had a presence in popular culture for nearly 70 years, from its heavy use on the electronic score for the 1956 film Forbidden Planet to creating the voice of the Daleks on Dr. Who. It was also a go-to effect for Deep Purple’s keyboardist Jon Lord and a favorite of Chick Corea, who both used it to treat their electric keyboards and organs.

To best illustrate ring mod, we’re going to create four simple, ring mod–based patches from scratch: a gritty organ, an accelerating-spaceship effect, a steel drum, and church bells.

For a deeper look into ring modulation, check out Synth Clips episode 21 — “Ring Modulation” from Sweetwater’s synth guru Daniel Fisher.

Creating a Gritty Organ Patch

Up first, we’ll design a gritty organ patch using the Behringer Odyssey analog synthesizer. The Odyssey has two fat-sounding oscillators and a ring mod available in its audio mixer section. But, most importantly for this patch, the Behringer Odyssey is a duophonic synth, capable of playing two notes at a time — one note per oscillator. This patch is extremely straightforward. The oscillators are set to sawtooth and in tune with one another, which is performed manually on the Odyssey just like tuning a guitar. In the example, I’m playing dyads (two-note chords) comprising a first and a third with a fourth sneaking in at one point. Here’s what it sounds like sans ring mod:

Playing dyads on the Behringer Odyssey with both oscillators set to sawtooth.

Now, let’s hear what the ring mod sounds like on its own:

The ring modulator amplifies the sum and difference of the two notes being played and emits dissonant tones.

In isolation, the ring mod has a snarling, discordant growl, but the magic really happens when you blend the ring mod with the original, unaffected sound, like so:

Blending ring mod with the original signal produces a thick and aggressive organ patch.

By mixing in roughly 75% of the ring mod signal with the straight oscillators, we’ve created a thick, aggressive organ sound with a ton of attitude. The combination of ring mod with the Odyssey’s duophonic capability is, in part, why the Odyssey is sometimes referred to as the first “punk rock synthesizer!”

Blast Off with an Accelerating-Spaceship Patch

For the next patch, we’ll design a signature ring mod effect — an accelerating-spaceship sound — on the Novation Bass Station II analog synthesizer. Like the organ patch, this is fairly easy to accomplish. I set both of the Bass Station’s oscillators to sawtooth, but I routed an envelope generator to dramatically modulate the pitch of Oscillator 2. Listen to the two clips below to hear the difference.

Raw sawtooth tone from the Novation Bass Station II.

An envelope generator is routed to the pitch-modulation input of Oscillator 2.

Now, the ring mod goes to work, generating a sweeping amplification of the sums and differences of the static and pitch-modulated oscillators. To get the most out of this effect, the oscillators are completely turned down in the Bass Station II’s mixer section, and the ring mod is turned up all the way.

The ring mod exaggerates the contrast between the static oscillator and the pitch-modulated oscillator, producing a stellar sci-fi effect.

Hammering Out a Steel-Drum Patch

As we’ve discussed, ring mod excels at creating metallic sounds. So, for our next patch, we’ll use ring mod to create a synthesized steel drum. The Arturia Modular V software synthesizer is an excellent platform for this type of ring mod–based sound. Based on a legendary vintage modular system, Modular V’s ring mod is a discrete module that uses its own oscillator to set the frequency of the modulation, giving you detailed control over the timbre of the ring mod effect. To set up this patch, load the “2 OSC Mono” preset from Modular V’s template menu and select a ring mod module to fill an empty slot on the top row. Next, route the VCF output to the ring-mod input and the ring-mod output to the VCA input. To further shape the sound, route the output from an envelope generator to the ring mod depth control. The patch is illustrated in the image below.

Dialing in the steel-drum sound took some tweaking, focusing on the ring mod frequency, ring mod depth envelope, as well as the VCA’s ADSR envelope. However, it didn’t take long to stir up some “Under the Sea” vibes! Compare the following clips.

Arturia Modular V steel-drum patch without ring mod.

Arturia Modular V steel-drum patch with ring mod.

Casting a Clangorous Church-Bell Patch

While we’re at it, we might as well make a church-bell patch, which is just a hop, skip, and a jump away from the steel-drum patch we created. To transform the steel-drum patch’s bright island timbre into a gloomy, clangorous church bell, I dropped the range of Oscillator 1 from 16 to 32 feet, lowered the ring mod frequency, and cranked the depth of the effect while increasing the release time on the mod depth envelope.

Hit it with some large hall reverb, and you have instant tintinnabulation!

With some minor parameter changes, we can transform a steel-drum patch into a church-bell patch.

Put a Ring on It!

Once again, we’ll end this Simple Guide to Modulation with a musical example employing the four patches we created using ring mod as our primary sound-design tool. The track comprises six elements: drums created from a sampled Oberheim DMX drum machine programmed in Native Instruments Battery 4 (available in Native Instruments Komplete 13), a bass line, the gritty organ patch on the Behringer Odyssey, the spaceship effect from the Novation Bass Station II, and the steel drums and church bells from the Arturia Modular V.

A short musical piece employing the four ring mod–based patches we created in the examples above.

Conclusion

There we have it — a very simple guide to modulation with ring mod. Hopefully, this article shows that, even though ring mods are generally regarded as “weirding” devices, they can also be used to make musically useful patches that work well in a melodic context. Of course, when it is time to get strange, ring mod is a great place to start!

If you want to know more about modulation, then check out the other articles in this series.

“A Simple Guide to Modulation: LFO”“A Simple Guide to Modulation: Envelope Generators”“A Simple Guide to Modulation: Sample & Hold”
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