Fairfield Circuitry Randy’s Revenge Review

Review of: Fairfield Circuitry Randy’s Revenge

Reviewed by: Rating:4.5On December 15, 2017Last modified:December 15, 2017


Ring modulation… that clangy, metallic, atonal effect that recalls the mechanical sounds of an industrial assembly line or a sci-fi robot gone haywire. It takes the harmonious melodies and chords you feed it and spits out a gurgling, disassembled juxtaposition of your initial riffage. If you can manage to tune the ring mod effect to harmonize with a chord, it’ll add richness and texture to your base chord, but anything played beyond that will most likely be a cacophony of beautiful bell-like tones and/or harsh dissonance. While these rules – or lack thereof – may apply to many ring modulators, I’m not describing the sounds of just any ring mod. This is the Randy’s Revenge by Fairfield Circuitry, and your audio signals will soon know its sweet wrathful embrace.

Ring Mod’s Relevant Roots

Ring modulation has been used in music since at least as early as the late 1940’s. In the 60’s Robert Moog licensed patented ring modulation circuitry to be used in Moog’s modular synthesizers. And Maestro, famous for their iconic Fuzz-Tone, made some of the first ring modulation effects for guitarists. Go listen to the solo in Black Sabbath’s Paranoid on headphones (we’ll wait); that mangled guitar sound you’re hearing panned to the right opposite the solo? Yep, that’s ring modulation in action.

But ring modulation has come a long way since its inception and earliest use in music, and there have been many incarnations of the classic effect in various hardware forms. The effect can be achieved digitally, and many such ring mod algorithms do exist, but Randy’s Revenge is a glorious all-analog ring modulator with a few other tricks up its precarious sleeve.

Three Quick Maths

By multipling your signal with either a square or sine wave VCO, the ring modulation effect is achieved. The new tones generated are the sum and difference of the source audio and VCO as they’re eaten and regurgitated by the four-quadrant multiplier. So your input signal × VCO = a whole lotta crazy harmonious and dissonant tones.

Here’s a quick feature rundown before we go face-to-face with Randy. Don’t be nervous. He’s actually quite nice once you get to know him.



  • All analog signal path
  • Knobs for output Volume, wet/dry Mix, LPF (Low Pass Filter), and Freq (VCO Frequency)
  • Waveform flip-switch selects between Square & Sine wave options
  • Frequency Range flip-switch selects between Lo (0.5Hz – 45Hz) and Hi (18Hz – 2.4Hz) options
  • Internal dip-switches allow custom CV functionality


  • True bypass switching
  • 1/4” mono input/output jacks
  • 1/4” stereo CV jack
  • 2.1mm DC connector
  • 4.7” x 3.8” enclosure dimensions


  • Input impedance 1 MΩ
  • Output impedance 1 kΩ
  • Power supply 9 to 9.6 VDC
  • Current draw 85 mA

Visit Fairfield Circuitry for more info about Randy’s Revenge.

Sound & Performance:

Randy’s Revenge is pretty easy to come to grips with. Setting the Volume knob at just above noon starts you off with a signal at around unity gain. There’s plenty of volume boost on tap if you need it. With the Mix knob fully counter-clockwise, you’ll be hearing just your dry signal. Turning up the Mix is where things start getting interesting.

With both of the pedal’s flip-swiches set to the right (to Sine & Lo, respectively), a pulsing vibe-ish sounding tremolo effect will be heard when the Freq knob is set towards to the left of 1 o’clock. The rate can get incredibly slow when Freq is turned to the far left. Pushing it up past 1 o’clock brings in some of Randy’s signature ring moduation, a hint at what kinds of crazy sounds are in store.

The pedal’s Lo setting sets the operating range of the VCO between 0.5Hz – 45Hz to produce these “trem-vibe” style effects. If you push the Mix all the way up, it’s more like a fully wet tremolo. The test unit I played had an almost slightly offset sine wave sound that gave it a unique feel that I really enjoyed. With the Mix around the middle the throbbing fluxuation of tonality blended with the dry signal made it sound more vibe-like. This mode is already very playable, and using an expression pedal to control the Freq parameter can create a dramatic shift in speed of the modulation effects. It’s also worth noting here that if you flip the Waveshape toggle switch to Square, you can get some very cool choppy trem sounds with the Mix cranked up. Push the pedal to toe down for some very fast rate speeds and cool sub-oscillating tones.

Flipping the Frequency flip-switch to Hi cranks up the speed range to between 18Hz – 2.4kHz. From here I recommend starting out with the milder Sine waveform setting. Sweeping through the Freq knob produces an incredibly wide range of pitched sounds as your audio signal is consumed by Randy’s lust for Revenge. This is probably my favorite setting as the sounds aren’t too intense, and you can find plenty of sweet spots for tuning the ring modulation to a note or chord. You can often find a Freq setting where a few chords will create musical harmonies while other chords produce chaos… beautiful twisted chaos.

From here it’s worth mentioning the LPF knob. This controls a Low-Pass Filter on the wet signal that’s useful for taming the high frequencies. It’s a full range filter, not a generic tone knob, so with the Mix set fully wet, you can potentially cut the sound all the way down to inaudible. You’ll most likely use the LPF along with the Mix to careful dial in the amount of ring modulation in your signal path and tame any excessively bright frequencies when pushing the Freq knob up into insanely fast speeds with higher pitched tones.

If you flip the Waveform toggle over to Square, the ring modulation gets even more intense. This is great for all kinds of expression pedal insanity. Try sending the effect into a delay and/or reverb for screaming sci-fi laser sounds and ascending UFO risers that echo in the distance. Since the Square setting is more intense and abrasive (in a very good way, mind you), the LPF will come in handy to reap the benefits of the Square wave’s impact on the ring mod sound. I’ll often keep the LPF as low as around 11 o’clock when using the Square waveform.

CV Expression Control

One of the most interesting aspects of Randy’s Revenge is it’s unique programmable CV (control voltage) jack that affords a wealth of cool possibilities for integrating the pedal within a pedalboard setup or modular rig. At it’s most basic, you can plug in an expression pedal to control the VCO frequency (Freq knob) for real-time ring mod pitch control. Accessing the dip-switch panel inside the pedal will let you, say, switch to controlling the Low Pass Filter, a cool option for sweeping into the ring mod effect when a specific pitched tone is already set via the Freq knob. You could also split functions across the Tip & Ring of a TRS CV cable to control the oscillator frequency and filter frequency simultaneously. You can even turn Randy’s Revenge into an unassuming little low pass filter by connecting the reference voltage to the oscillator output by shorting the tip and sleeve. (We’ll discuss the CV possibilities more in an upcoming article.)

As for where to place Randy’s Revenge in your signal chain, there are no rules really. It’ll scramble anything you feed it, so experiment to find the best results for your rig. I often treat it like a pitch effect and place it after a compressor but before overdrive and distortion effects. This will generally yield smoother results overall. But you can also use it after a distortion effect. When using those Square-Waveform-plus-Lo-Frequency tremolo settings, it’ll really chop up a heavily distorted sound nicely. In the faster Hi speeds, the ring modulated pitch sweeps with have additional harmonic content that can be interesting to explore.

There’s not much to complain about really. If you like ring mod effects, this one sounds amazing. The only technical improvement I’d like to see would be a Fine control for easier tuning of the ring modulation when trying to set it to a stationary pitch. It’s not really an issue in the studio as you can still get the knob set just right, but on stage it might help if you want to keep the pedal as in tune as possible. Other than that, Randy’s Revenge is hard to top when it comes to quality analog ring modulation.

The Fairfield Circuitry Randy’s Revenge is one of the most musical, accessible, and versatile analog ring modulation pedals ever devised. From it’s signature ring mod effects to brooding vibe sounds, hard chopping tremolo, and warm low-pass filtering possibilities, this pedal extends its usability well beyond the novel and obscure rind modulators that came before it. Real time expression pedal control adds to the fun, and modular synth users will surely enjoy discovering clever ways to interface Randy’s Revenge with their CV compatible gear.

That concludes our Fairfield Circuitry Randy’s Revenge review. Thanks for reading.

Gabriel Tanaka

Similar Posts

Leave a Reply

Your email address will not be published.