Review: Source Audio C4 Synth Pedal – Taking Guitar Synth FX To New Heights

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Source Audio have recently started to majorly turn heads in the effects pedal market for all the right reasons. This year alone we have seen the arrival of a number of groundbreaking units from the Boston pedal makers and these inclusions have really boosted the prestige of the company. The C4, Spectrum and Collider pedals have all received critical acclaim from the tough to-please-effects crowd, and for good reason.

The team at Source Audio are responsible for the technology we find in Nintendo Wii controllers, so it’s no surprise one of the first units on the market under the Source Audio name was the ‘Hot Hand’ expression controller. This wireless controller is worn like a ring on the user’s hand and through distance manipulation you can effect drive levels, modulation, bit crushing and much more. Pretty neat.  

But it’s the recent ‘One Series’ pedal range that has really catapulted the company into the forefront of the guitar market. Utilizing 56 bit processing power, stereo ins and outs, MIDI functionality and the massive editing power of their Neuro application, each pedal in this line is packed with features. I recently got my hands on the C4 Synth pedal and -spoiler alert- it’s incredible.

The C4 harnesses 4 independent voices, each can be assigned to an oscillator wave shape, monophonic or polyphonic pitch shifter, intelligent harmonizer, sequencers, or dry signal to distortion, tremolo, and filter effects. Stack these voices to create truly unique and out-of-this-world synth-effects.

One of the biggest selling points for any pedal in the One Series range is the ease of use, and functionality of their Neuro editing software — available on desktop or mobile. This also acts as an online hub where users can upload their favorite settings and tweak factory presets. Here’s the thing – it actually works. How many times have companies pursued this concept? To me, they’ve always fallen over because they’re too time consuming or there’s not enough presets or the software is clunky. Source Audio’s Neuro has resolved those issues and absolutely nails it on all fronts. You can tweak parameters to your hearts content and find new presets daily for each pedal uploaded from users all over the world. 

Being a bassist, my first question with synth and pitch effect pedals is always – ‘Yeah that sounds great, but how does it track?’ Synth pedals are notoriously laggy when it comes to bass-land. Well, I don’t know what voodoo Source Audio have got going on under the hood of the C4, but apparently, that’s no longer something I need to worry about. With an additional control for ‘Input Sensitivity’ you can really dial in that perfect dynamic control (which varies differently for each of my basses). I can say with complete honestly, the C4 has the best pitch tracking I’ve ever encountered on a synth pedal. 

I’d highly recommend the C4 to anybody interested in synth pedals. Players who are familiar with how to use synthesisers will likely get more use out of the in-depth editing functionality, but with the enormous library of presets available for free via Neuro, I wouldn’t call it essential. Hell, I only have a rudimentary understanding, and I’m having a ball tinkering with filter types and oscillator wave shapes.


We’ll have a demo coming soon, in the meantime, here’s an official video:

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