Vitruvian Mod – Ring Modulator old version

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A ring modulator with the soul of a synthesizer

A ring modulator that is easy to use, even live.



A ring modulator with a synthesizer soul. Prepare yourself for the Vitruvian Mod. Inspired by additive synthesis and set apart from other ring modulators by its pitch detection capabilities and the ability to be tuned by site, the Vitruvian Mod is a ring modulator you can love.

What is ring modulation?

Ring Modulators multiply two signals (input and carrier.) The end result is the sum and difference of the two frequencies. While the math is simple the results are often dissonant and unmusical.

Most ring modulators are simply hard to use. There are interesting sounds to be created, but controlling the effect is often a chore, especially dialing it in live. It’s not the type of effect which can haphazardly set and expect predictable results. Sometimes you just want to plug in and play.

We set out to solve the usability issues, but not limit the range of the effect. This is where the entropy switch comes in. It is an ‘ease of use’ toggle. Set to either order or chaos this switch alters the functionality of the carrier and fine tune knobs.

Pitch detection

One of the interesting ways to use a ring modulator is to tune it to add harmonic tones. With a traditional ring modulator this only works with a few notes. Other notes will render varying levels of unmusical dissonance. We added pitch detection and the ability to offset the carrier from the input. The offsets are based on harmonic ratios, creating interesting harmonic structures to everything you play.

Fixed Carrier modulation

Classic ring modulation sounds are available as well by setting the tracking switch to null 0. Unlike the typical coarse/fine tune arangement, the Vitruvian Mod’s carrier knob has seven fixed steps. When the entropy switch is set to order the carrier knob steps through the notes E A D G B E A. Perfect for guitar! The fine tune knob can detune the carrier up or down by a minor third. With the entropy set to Chaos there are eight octaves of range from ~19Hz to ~2.5kHz.

We designed the effect so that even if you don’t understand what it does the controls feel natural and intuitive.

For best results:

We recommend using the Vitruvian Mod early in your signal chain. Running overdrives and fuzzes after the Vitruvian Mod can really bring out the effect’s harmonic structure. Add a wah pedal after the Vitruvian Mod for synthesizer like effects. For leads try adding delay and modulation.

Using a compressor in front of the Vitruvian Mod will add sustain.

Control Matrix

Entropy switch – Set to order for ease of use. Set to chaos for wider range.

Tracking switch – Set to HI or LO for tracking modes. Set to null (0) for fixed carrier mode.

Carrier – Controls the internal carrier in seven fixed steps dependant on entropy and tracking settings.

Fine – Used to fine tune internal carrier dependant on entropy and tracking settings.

Modulation – Adjust the amount of ring modulation. Turn to the left for fully clean. Turn to the right for fully modulated.

Volume – Overall output of the effect


* Based on Just intonation.


Design- Brian Marshall, Tom Eddleman

Code- Tom Eddleman

Artwork- Greg Schober

Original pitch tracking algorithm developed by Don Stavely.


Notes from the design team:

Brian’s notes-

One of the first things we discovered in designing the Vitruvian Mod was that equal temperament intonation (chromatic scale) was not always useful for tuning tracking modes. The chromatic scale is an invention that largely sounds good to us because we are used to hearing it. We used just intonation which is based on harmonic overtones. While the fourth and fifth are the same, the major 3rd in just tuning slightly flat, the minor third is slightly sharp, etc. Using Just tuning to track the carrier renders sum and difference frequencies that are related to the original note played. The close attention to frequency ratios inspired the name Vitruvian Mod.

While the basic idea can be traced back to post WWII ring modulation synthesizers the inspirations for this pedal are wide and varied. Synthesizers and old school sci fi soundtracks for sure. Korg and Roland included ring modulator on many of their dual oscillator mono-synths. For me it can all be traced back to the Commodore 64 and the MOS Technology SID Chip. The SID chip was designed by Bob Yannes who later went on to found Ensoniq.

By today’s standards the SID chip sound engine found in the C64 is rudimentary and simplistic. 3 oscillators, a few different waveforms, multimode filters and the ability to RING MODULATE two of the oscillators. At the time it was light years ahead of anything in a consumer level device. A couple decades later these chips were being harvested to build synthesizer modules and the chips still often sell for more than the old computers themselves.

The remarkable thing about the ring modulation in the C64 is that the two oscillators can be controlled separately. It’s not a typical fixed carrier modulator. You could modulate two completely different melodies. There were certainly interesting, if not terrible sounds to be made. One of the things that I found most interesting was to use the same melody, with one transposed. At the time I had no idea of how ring modulation worked, but through experimentation found things that worked musically.

Back in the early 1990′s, I finally got a chance to try a ring modulation pedal at Portland Music. I was disappointed. It seemed all I could really do is create the “bad” sounds. The sounds I spent all that time trying to work around and away from.

Tom’s notes-

Ive always thought an ideal compositional tool would be a device that translated the source sound into a controllable sound medium., like sampling street sounds, organizing them, then pitch tracking them to control a synth. A direct method of music translation that bypasses the performer, or musician translation; to remove the abstraction of the sound from the music, if that makes sense.

For my senior project i made a synth that had a freq to cv input that controlled 4 oscillators. the oscillators went to a multiplexer that sequenced them. So anyways, the Vitruvian Mod kind of work towards that goal of composing music with sounds in a music concrete type of fashion. I used to be really fascinated by the works of composers in the 50′s. There were a few records at my school from some of those people: Milton Babbitt, Otto Luening, Vladimir Ussachevsky, Pril Smiley, Edgar Varese, Morton Subotnik, Stockhausen. The Columbia Princeton releases were really great, they had the first electronic music center with one of the first RCA synthesizers. and they sound incredible! Really creative as well because there was no precedence, and the composers were really inspired by the technology. and, despite the fact that there were only a handful of instruments at the time, it’s really difficult to figure out how the music was made. There were even a couple of Quadraphonic Lps.!!, but my school didn’t have playback for them, you could only hear 2 channels with a normal record player.

Anyways, where was I going with that… ring modulators, one of my favorite effects, and to be able to use that works with the input signal is awesome.; i think Mario Davidovsky would be proud.

I think you should do a video with a cellist!! in an empty cathedral.

About The Vitruvian Mod:

Powered by a regulated 9VDC to 18VDC adaptor with a negative center 2.1mm barrel style plug.

If using a “daisy chain” power supply, all other pedals MUST be negative ground.

Current draw is less than 100mA.

Length 4.4″ X Width 2.3″ X Height 1.0″

Input impedance- 500K.

Output impedance- ~5K.

The Vitruvian Mod is hand made in Oregon.

Die cast metal enclosures for durability.

3PDT switches for true bypass switching.

Red LED indicator.

Three-year limited warranty.

Weight12 oz
Dimensions4.375 x 2.375 x 2.25 in