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Source Audio C4 Synth Pedal

Modular Synth Pedal for Guitar and Bass
$269.00

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Source Audio C4 Synth Pedal
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A Powerful Modular Synth Pedal for Your Guitar or Bass

Source Audio’s C4 Synth Pedal packs the power of a classic Eurorack modular synthesizer into a compact, rugged effects pedal for your guitar or bass. With four simple controls, a choice of three guitar/bass synth effects, and multiple methods of patch storage and recall, the C4 is remarkably easy to use and it boasts wicked-fast response, incredible tracking capability, and limitless sonic potential. Just plug and play to immerse your axe in an ocean of killer synth sounds. When you’re in the mood to dive deeper into sound design, connect the C4 to Source Audio’s Neuro Desktop Editor (free download for Mac and Windows) or Neuro Mobile App (free download for iOS and Android) and the sky’s the limit.

Dive deeper with Neuro Editor

In the desktop and mobile Neuro Editors, you have the tools to create retro-futuristic synth patches beyond your wildest dreams. Use the C4’s four parallel voices, three oscillator wave shapes, 10+ envelope followers, 20+ modulating filters; plus distortion, tremolo, pitch shifting, intelligent harmonization, programmable sequencing, and more to craft your sonic masterpieces. It’s all there — from classic synth tones you’ve always wanted to deploy from your guitar or bass to those ephemeral flashes of brilliance you’ve dreamed of, but never actually heard. On a tight deadline? If you need great sounds quickly, simply call up one of the countless presets curated by the Source Audio team or the growing legions of C4 users.

The C4 backstory

Source Audio’s Chief Engineer Bob Chidlaw, inspired by his own Eurorack system, wanted to share the wealth with guitarists and bassists by designing a powerful synthesizer in a Source Audio One Series pedal format. The C4 is a stunning accomplishment. This compact synth pedal has not only bewitched the legions of guitar and bass players at Sweetwater but it’s also captured the imaginations of serious synthesists, like our Director of Product Optimization Daniel Fisher, who are enthralled with all the sonic goodness Source Audio has been able to pack into this little gem. Design your sounds and burn them directly to the pedal in any of the C4 Synth’s 128 preset positions, save them to your own personal effects library, or share them with the C4 Neuro community. Trust us — you’ll be blown away by the C4.

Source Audio C4 Synth Pedal Features:

  • Unprecedented sound-sculpting options with modular-synth-inspired software editors for maximum sound exploration
  • Powerful Neuro Desktop Editor (free download for Mac, Windows)
  • Neuro Mobile App (free download for iOS, Android)
  • Create custom C4 Synth presets that can be stored on the pedal, saved to your private cloud library, or shared with the Neuro community
  • 128 MIDI-accessible factory presets via optional 3rd-party MIDI controller/USB host (sold separately)
  • Ever-growing preset library created by Source Audio and the C4 Neuro community
  • Plug and play using 3-position toggle switch to select from the C4’s three pre-loaded synth patches
  • Mix together any of the C4’s four independent voices
  • Assign any voice to oscillator wave shape, monophonic or polyphonic pitch shifter, intelligent harmonizer, and sequencers; or dry signal to distortion, tremolo, and filter effects
  • Mix and match any of the C4’s three oscillator wave shapes (sine, square, or saw) for pure synth tones
  • Select from 11 envelope followers with adjustable attack/decay and ADSR triggering envelopes
  • Choose from 24 filters, controllable with an envelope follower or independently modulating LFOs (Low Frequency Oscillators)
  • 14 onboard LFOs to control modulation of filter, vibrato, and tremolo
  • Eight available LFO wave shapes, including sine, square, sample and hold, sawtooth, and more
  • Run two, simultaneous 16-step sequencer patterns
  • Choose from pre-programmed sequencer patterns or create your own custom patterns
  • Two modes of operation: Standard Mode for classic stompbox operation; Preset Mode to save user presets (including all knob positions) to each of the three toggle switch positions
  • Stereo inputs and outputs: use Neuro Editor panning controls to route each voice to any location in the stereo field
  • Universal Bypass: switchable analog buffered or relay-based True Bypass
  • MIDI control connects to Neuro Hub (sold separately) for access to 128 presets with MIDI program change (PC) messages, control of pedal parameters with MIDI continuous controller (CC) messages, or assigning LFO speed with MIDI Clock
  • USB port (class-compliant USB-MIDI) for plug and play with Mac and Windows recording software; connectivity with Neuro Desktop Editor for deep editing and pedal firmware updates (USB cable not included)
  • Control input jack for external expression and tap tempo control: use with optional Source Audio Dual Expression Pedal (sold separately) for expression control for multiple parameters; or Tap Tempo Switch (sold separately) to adjust LFO rates on the fly
  • Durable, compact anodized aluminum housing with sturdy hardware
  • Includes 9V DC power supply (300mA, negative tip; pedal draws 165mA)

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Tech Specs

  • Pedal Type: Guitar Synth
  • Analog/Digital: Digital
  • Effects: Neuro Software: Modulating Filters, Distortion, Tremolo, Pitch Shift, Harmonization, Envelope Followers
  • Presets: 128 x MIDI presets, 6 x accessable
  • Inputs: 2 x 1/4"
  • Outputs: 2 x 1/4"
  • MIDI I/O: USB
  • USB: 1 x Mini-B
  • Other I/O: 1 x 1/8" (expression, tap tempo)
  • True Bypass: Yes, Switchable to Analog Buffered
  • Bypass Switching: Relay Based
  • Software: Neuro Desktop Editor/Mobile App (Mac, PC, iOS, Android)
  • Power Source: 9V DC power supply required (included)
  • Power Usage: 165mA
  • Height: 2.0"
  • Width: 2.75"
  • Depth: 4.5"
  • Manufacturer Part Number: SA249

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Customer Reviews

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Rated 5/5

Fun in a box!

I use the C4 mostly for bass. It's a blast to use. Range of tones is great. So flexible. From subtle grind or modulation to space invasion the C4 will set you up. Very glad I didn't get a limited function synth pedal. No noise. And no coloring of signal when bypassed. The app is easy to manage. Lots of resources within the community. I use both the IOS and desktop app. I plan to pick up a Disaster Area switch but have been too lazy to choose the unit. Get one. And spend a couple weeks getting familiar with the app and operation. It's wirth the effort.
Music background: Lifer
Rated 5/5

Leaves me with an open mouth

Ok. So this pedal might be the best value of any pedal...like ever. Just so you know what you're looking at, this is not a typical synth pedal. This is a MIDI interface in which you upload either community-created settings or your own settings directly to the pedal via a USB-to-Mini-A cable. This cable is not included and get one long enough to go from your computer to wherever your pedal board is (you can try out settings on the fly as you download them). It should be noted that a total of 6 presets can be uploaded to the C4, but in Source Audio's "Neuro Hub" app (where you create & download presets) you can have up to 128 presets stored and ready to go.

Go to the Source Audio site as well as YouTube tutorials to get a taste of what this can do (which is A LOT).
Rated 5/5

Just get one!

I just received the pedal today and plugged Helga my MTD 635-24 in and you're off! It's easy to connect to a small Bluetooth receiver and just plow through all of the community presets in the Neuro app! You'll honestly spend the whole first day there just seeing what folks have been able to do with it. I can't wait to get back on the road and set it up for live applications. If you're in the market for a synth/wah/octave/phaser/arpeggio/do it all pedal here it is! Have fun y'all, love!
Music background: Professional Bassist and Endorsed artist with MichaelTobias Designs USA, Bergantino Audio Systems, GHS Strings, Bartolini, and Tsunami Cables
Rated 5/5

A musical instrument in its own right - You need to invest some time to get more out of it

This is an incredible, cutting-edge device that instantly puts the 70's FM synthesis sound in your hands, and much much more. I have just barely gotten started with this thing, and I am very impressed with what I've seen so far. Here are my points, that no one else seems to be making:
1) It tracks insanely well for single-line playing. Good picking technique is a must. I've played for 40+ years so that's not a problem
2) Start by putting it in the front of your device chain, or at least only behind your compressor if you have one. I experimented with this first and found that while it still tracks really well, having signal-altering devices in front of it can cause off-note harmonies at random. Where I have it now? It never misses. Never. The performance of this thing is off the charts.
3) SA thoughtfully put six instrument patches into the six user-accessible presets, so you can explore the device right away. The little Alt button at the top lets you switch between the banks.
4) The Nero editor works flawlessly and the USB connectivity is perfect. My homebrew Windows system immediately detects it and the editor works well with it. I think the interface is actually quite straightforward. RTFM.
5) I have not gotten around to getting keyboard patches on it yet to test its polyphonic voicing (i.e., CHORDS, man). The six added patches do not track well in this area. No big deal. SA has a library of patches that you can download, and there are some thriving communities around this thing. I am gonna be nosediving into this thing, because it gives me capabilities I've never had before on my $3500 pedalboard that I've spent 4 years building.

A healthy curiosity will serve you well. Highest possible recommendation from me.
Music background: 40+ years, occasional playing out
Rated 5/5

C4 synth pedal

I did a lot of research on this pedal, it is pretty complex. I love that it contains the filters from the Spectrum pedal so your getting access to two pedals. Can't beat the price for what you get. This is a very large rabbit hole.
Music background: 52 years guitar in hand
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