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The OWL is an open source, open hardware, reprogrammable effects pedal designed for musicians, coders, and hackers. Read more

London, UK Hardware
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This project was successfully funded on July 1, 2013.

The OWL is an open source, open hardware, reprogrammable effects pedal designed for musicians, coders, and hackers.

London, UK Hardware
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About this project

With some coding and DSP knowledge, the OWL can become any kind of audio effect that you can imagine. Effects can be combined in any number of ways by chaining or switching between them.

Using a provided C++ framework, effects can be developed, compiled and loaded to the on-board ARM Cortex M4 chip with no proprietary tools or hardware-specific knowledge.

The OWL gives coders the chance to implement their own effects and become part of an open-source audio developer community. For those who don’t write code there is a growing collection of patches available for immediate download and use in the patch library.

With a strong emphasis on open-source hardware and software, the OWL is perfect starting point for anyone wanting to experiment with embedded audio, or for those wanting to to learn more about audio programming and Digital Signal Processing in general.

For musicians:

  • Load patches from your computer via USB
  • Collection of sample patches available and growing
  • Standard guitar pedal inputs/outputs

For developers:

  • Write code for a hardware DSP architecture in plain C/C++
  • no hardware specific coding required
  • Open source platform and tool chain
  • Access to all low level ARM functions

Patch class

Implement this class to create your own Patch. Call getParameterValue() to get a knob position. The processAudio() method is called on each audio block.

Example Patch

A simple Gain patch that multiplies each sample by a value between 0 and 1.

Test your patches with the Owl Simulator

We developed a C++ project called the Owl Simulator (OwlSim), that makes it easy to test your patch. The OwlSim uses the Juce library and is cross-platform (Mac / Windows / Linux). Put your patch in the OwlSim and you will be able to run it as a VST/VSTi/AU in your favorite DAW (Reaper, Logic, Live, Nuendo, Ardour...). The OwlSim allows easy testing, debugging, or just being able to run your favorite patches on your computer for a home studio session !

  • 168MHz 32bit ARM Cortex M4
  • 1mb RAM, 1Mb Flash memory
  • Integrated DSP, FPU, DMA
  • 12bit / 96kHz codec
  • 4 assignable control knobs
  • Bypass switch
  • Indicator led
  • Mono Jack input (6.35mm = 1/4 inch), unbalanced, Z=1MΩ
  • Mono Jack output (6.35mm = 1/4 inch), unbalanced, Z=1kΩ
  • 9V DC power socket
  • mini USB for patch upload

As we've hit all our stretch goals, all OWLs also include

  • Expression pedal or switch input jack
  • MIDI control via USB
  • Hardware codec
  • Push button bi-colour LED
  • Stereo Input/Output
  • 1mb of RAM 

+ £12,000 Expression Pedal / External Switch - funded

We will add an input jack to connect an expression pedal or an external switch. Control moving filters, wah effects, or tap tempo by foot!

+ £16,000 USB MIDI - funded

We will implement MIDI over USB functionality. This will allow you to control patch parameters from external MIDI controllers, or send MIDI signals from the Owl to other devices.

+ £20,000 24bit Codec - funded

A high-resolution 16/24 bit 96kHz hardware codec will be integrated for input and output processing.

+ £24,000 Push button bi-colour LED - funded

An extra push button mounted on the surface to allow more control. The switch will contain a bi-colour light emitting diode for visual feedback. 

+ £28,000 Stereo Input / Output - funded

Another input and output will be added to allow stereo and dual mono effects. Great for delays, reverbs, dual effects and advanced signal routing!

+ £30,000 Memory Extension - funded

If we reach this target we will increase the amount of available memory to 1Mb RAM.

We believe in open source and open hardware, and hope that publishing the OWL source code and hardware designs will encourage you to get involved with the process of creating awesome technology. All our source and documentation is published under the Gnu GPL and is available here on github. Pull requests welcome!

Tom, Martin, Guillaume and Sasha.

The OWL is being made by Rebel Technology, a well respected and established synthesiser manufacturer on the modular scene.

Risks and challenges

Having already developed electronics and software products, and having designed a working prototype of the Owl, we know that we will be able to deliver the project as planned. We will produce the Owl at a rate of 100 units per month for the first batches. The following problems could occur after the campaign:

- Parts availability and sourcing the necessary parts and custom components.We have developed great relationships with all our providers, most of whom are local, but shortages and delays may still happen. For critical components we have several sourcing options, and smaller delays will be absorbed in our time margins.
- Although we allowed plenty of time for pre-production, unexpected hardware design issues might delay the production by a couple of weeks.

Learn about accountability on Kickstarter



  • You selected
    Pledge £1 or more

    30 backers

    Interested parties. Keep up-to-date on the OWL Kickstarter with this reward level. You'll get a mention on the product website when it's done, and every penny is gratefully received.

    Estimated delivery:
  • You selected
    Pledge £25 or more

    8 backers

    The OWLs are not what they seem. For discerning fans, we are offering the OWL t-shirt. If you want add a t-shirt to other rewards, just add £25 to your pledge.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge £165 or more

    50 backers All gone!

    Early adopter. Get the very first OWLs after the Saints have had theirs sent out. You'll receive your OWL and access to all the forums as fast as we can make it happen.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge £195 or more

    84 backers Limited (16 left of 100)

    Early Owl. OWLs from the next batch after OWL Saints and Early Adopters will be sent out to funders of this level. You won't have to wait for access to the forums and will be able to start writing and testing patches with the OWL Sim immediately.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge £220 or more

    3 backers

    OWL Unlimited. You receive the OWL pedal from the main unlimited production run, which will mean you get it long before and more cheaply than from shops and resellers.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge £250 or more

    24 backers Limited (76 left of 100)

    OWL Saint. This reward level is for our well wishers and most generous supporters. You'll get an OWL from the very first batch we make and a special mention in our hall of fame, along with our undying gratitude.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge £500 or more

    0 backers Limited (3 left of 3)

    OWL Workshop. You and a friend can come and spend a day with members of the OWL team in the London, UK office, learning about programming your own effects. The reward includes one OWL pedal to work on and take home. If you want two OWLS add £165 to your pledge. You'll need to pay for transport and accommodation yourself, but we'll provide lunch.

    Estimated delivery:

Funding period

- (32 days)