Source Audio C4 Synth review (short and thorough)

I tested the C4 with guitar and not bass, though I probably should have done both. Synth pedals like the C4 sound really good with bass, but I also like being able to draw out some of the higher register notes on an electric guitar, which helps with the testing process.

The C4 is a synth pedal with a lot of aggression, and just a few settings that were truly tame. It's more comfortable putting out almost a distorted synth tone, which sounds great as a melody line, chord progression, or underlying bass line.

To truly understand how these synth effects work, there's some technical research you might need to do.

But for my Source Audio C4 review, I'm focusing on the basics and out of the box tone quality.

If you have questions along the way, leave them in the comments section.

Compare to other Source Audio pedals

This table lets you compare live pricing and some basic specs between the C4 and a few other pedals in the same category.

Source Audio C4 Price Guide

This table keeps track of live pricing for the C4 from major retailers. Note that we don't post used options, though you can check places like Reverb and eBay for those.

Pricing updated Thu, March 30th, 2023.

Pricing from Major Retailers

Price Alert Tool (lowest price among listed retailers)

Price History (lowest price among listed retailers)

IDEAL FOR: Modern styles, recording, anyone who doesn't mind fooling with software for their pedals, bass/guitar

Overall sound and tone quality

A synth sound, especially in a guitar context, is very unique and difficult to compare. I've reviewed the Pigtronix Space Rip, which I found to be a little more guitar focused, while the C4 strikes me as more bass focused. Again, both pedals are branded to handle either instrument.

Read the full review: Pigtronix Space Rip

A lot of the C4's tones are deep and muddy, with the "frizz" of the synth sound resting over top.

I liked leaning on the mix knob and removing more of my clean signal. 

Per the bass-focus observation, I liked low notes better than high notes, just because on the higher register it seemed like I kept having to adjust the input. Though, nothing sounded bad.

If I were to compare to the Space Rip, the C4 is just a lot more wah-like - more of a filter pedal - while the Space Rip is far more aggressive and more of a buzz saw. I clipped together a really simple demo highlighting a few of the sounds.

You can't call this pedal subdued, because none of these synth stompboxes really are. But it's definitely a little more settled than some of the others ones I've messed with. It has a lot of use cases, especially if you go digging into the software, which I did not.

Does it cover up my guitar's clean/dry signal?

Synth pedals are a very saturating type of effect that's difficult to tame, so you will lose a lot of your dry signal on most settings. However, that's what the mix knob is for. You can dial in (or out) any amount of clean signal you want.

It's also worth considering that the synth sound on a guitar is better-served without much from your clean signal. It's supposed to sound futuristic and less like a guitar.

I found myself intentionally pushing the mix knob all the way up for a wet-only sound.

Don't by a synth pedal without a mix knob.

Control and tone variety

Not including the added flexibility that comes with the Neuro editor, the C4's control core is the three-wave shape selector in the middle.

If this means anything to you, they're as follows:

• Sine
• Square
• Saw

The three shapes are the three presets, though Source Audio doesn't make it clear which is which, and I don't know enough about the sounds to be able to tell. They're very distinctive from one another, with varying emphasis on filters, pitch shifting, and even some ambience.

Each preset responds differently to the two controls, which are simply labeled "Control 1" and "Control 2."

I do wish there was a little more clarity here for doofuses like me, but that didn't matter a ton.

When I only had two controls to worry about and three presets, I got more sounds than I knew what to do with. If I had never known about the software, I would be happy with the pedal as-is. 

There's plenty of variety and functionality with the two tweaking controls.

What musical styles are these used for?

So what are the use cases for a pedal like this? Let's go through some of the situations and styles where you might need a synth pedal:

Real synthesizers (not just guitar mimics) have been used in a ton of different music over the decades, so it's not possible to list everything. That said, here are some of the most notable:

1. Electronic music: Synths are a backbone in this style of music
2. Dubstep and electronic metal: Modernized, new wave rock and metal and more often making use of synth sounds, both for bass and guitar players. Tool, Three Days Grace, and Nothing More are just a few rock/metal bands off the top of my head that have used this sound.
3. Pop music: Pop and synths have been getting along since the 1980s, for better or for worse.
4. Rock music: This could probably be a sub-genre of number two, but progressive rock would certainly qualify as a synth genre. The Cure, Depeche Mode, and Rush are just a few examples.
5. Jazz music: Less commonly you'll see synths in jazz, particularly jazz fusion.
6. Film and video game scores: It gets away from bands and music genres, but film and video game scores are a major use case for synth tones and instruments.

Frequently asked questions

Source Audio C4 Review Conclusion

There's a learning curve if you really want to master this pedal, and synth effects in general, just because pedals like the C4 incorporate a lot of effects and signal processing technicalities. 

But the Source Audio C4 is also good out of the box if you just want to work with the three presets.

Try each preset and then tweak the two controls.

You'll get a lot of usable sounds and wah-like tones.

If you have questions about my Source Audio C4 review, drop them in the comments section below.

I'll do my best to help out.

Related Articles