Adding the latest Tube Screamer clone to your arsenal probably won’t make your sound more distinctive than it was yesterday. But if you’re looking for a pedal that will shock you out of a rut or get you noticed, look no further than the Sunsine Audio Harmonic Decoder.

The handmade Harmonic Decoder pedal is essentially a single-oscillator analog synth that can produce sounds ranging from 8-bit glitch and wah/filter to pitch shifting and fuzz. While it does a lot, it’s not a multi-effector. More accurately, it’s a phase-lock loop device, which means that a phase detector senses where your signal crosses a threshold and locks the oscillator onto the frequency and phase of the incoming signal.

I created mini conversations with myself where phrases would be answered by a totally different sound.

Decoding the Decoder
Considering the multitude of sounds you can extract from the Harmonic Decoder, its control set is relatively spare, and this encourages tweaking right off the bat. There are three knobs: Vol, Freq (which sweeps the internal clock of the oscillator and sync), and Depth (which sends a control voltage to the oscillator based on the envelope follower). There’s also a mini-toggle that lets you choose between Env (the envelope follower) and CV (control voltage). The latter’s toggle position also lets you use the 1/8" jack on the side of the pedal to accept a control voltage signal from devices like the Arturia MicroBrute synth and eurorack modular synthesizers, and expand the tonal palette available through alternate modulation sources.

Controlled Randomness
Depending on the extent to which you’re a control freak, the seemingly random way the Harmonic Decoder changes from one effect to another is either completely cool or totally frustrating. In an instant, your sound can go from a filtered Tom Morello effect to a Space Invaders blip. But spend some time with the Harmonic Decoder, and you’ll realize things aren’t as random as they seem.


Fresh new sounds.

Can take some time to figure out.


Ease of Use:




Sunsine Audio Harmonic Decoder

For instance, with Freq set at about 3 o’clock, Depth around 1 o’clock, and the mini-toggle switch set to Env, an odd but perceptible pattern emerges. All the notes I played between D and Bb on the 2nd string were pitch-shifted to a low octave, but as soon as I hit the 12th-fret B, the pitch-shifting effect jump to a higher octave. When I went lower than D, the device started glitching out and producing alien-like sounds. When I maneuvered the Freq knob, however, I was able to change the frequency at which the sidebands occurred. And when I knew what to expect, moments of befuddlement turned to inspiration. Using these timbral changes as unifying elements for composition took me in very interesting directions. And I created mini conversations with myself where phrases would be answered by a totally different sound, and to access such sounds all I had to do was play in a different register.

I also had fun playing two notes simultaneously because this forces the phase detector to choose between the pitches. You can hear the detector trying to jump between the two notes and it creates very striking tones at different intervals. Full chords, however, are a bit too much information for the pedal to handle.

The Verdict
In my time with the Harmonic Decoder, I only scratched the surface of what the pedal can do. But it made me venture beyond my comfort zone, and that gave me a completely new perspective on the guitar’s potential role in composing music. That’s not something a pedal can do every day. Factor in its power to reshape your tone in performance, and it becomes clear the Harmonic Decoder is a potent little package of controlled chaos.