Multi fx Stomp Box

I am looking to build a modular 'pedalboard in a box'.
It's so crazy it just might work...

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I am a trombone & guitar player, and have recently been messing around with guitar effects while playing in the studio, and would love to build a custom device that can act as an effects box with some real flexibility.
The setup I have recently used has been a bit bulky; with most guitar pedals being line level I have been using an 8 channel mixer to plug my mic in, then taking the aux out of that channel through the pedals and back into another channel on the mixer. This was handy as it gave me a wet and dry signal out of the setup. The pedals I was running through was a Yamaha Magicstomp (a great programmable multi fx unit) and a line6 floorpod (great for amp sims and other additional delays, plus the volume pedal was fantastic for controlling the level of wet signal).

I'd like to create a single pedal that I can use to do all of the above.

After a few rehashes, the plan currently is:

An all-in-one multi fx pedal based on the Raspberry Pi.

A usb interface will handle the sound input and output, and an Arduino based footswitch will control the parameters of the software running on the Pi.

Used to make first basic images of test board

ms-publisher - 1.85 MB - 11/03/2018 at 01:52


  • 1 × Raspberry Pi To process audio
  • 1 × Wah Pedal To remove internal circuitry and replace with the Pro Micro
  • 1 × AudioInjector Soundcard ADC / DAC conversion. Replaces the USB interface required previously
  • 5 × Footswitches
  • 1 × bundle of wires for connecting it all together

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  • Audioinjector working

    Craig Hissett03/31/2019 at 00:45 0 comments

    My test build is almost ready to rock!

    I've updated the software to use the new audio interface, and it works brilliantly. There's scope to really improve then latency and overall performance once finished.

    All i need to do is still out back panel holes, wire up my ins and outs, then test it.

    If it all fits nicely I'll be building a proper case for it :)

  • Building | Test casing

    Craig Hissett03/20/2019 at 01:02 0 comments

    Putting together a test enclosure to see how my estimates work out. It Is looking though a 5cm height at the back and 3cm at the front will in fact leave enough space inside for the Pi and hat. I may add 1cm to each height for comfort.

    Just need to rewire my switches, adjust my code for the new audio interface and it should be ready to test. Once testing is complete it'll be rehomed in a much better case.

  • New Arrival | Audioinjector HAT

    Craig Hissett03/19/2019 at 12:09 0 comments

    Ah, isn't it beautiful?!

    Now, to crack on with assembling the test case.

  • Enclosure v1

    Craig Hissett03/11/2019 at 01:03 0 comments

    Here is the first iteration of my case:

    Tomorrow I will get this cut out at work and stick together; I have added a cut out for the Pi ports on the back, but will need to drill out the sockets for the xlr/Jack inputs x2 and the jack sockets  out x2 and a headphone jack out.

    The analog expander chips I have ordered won't work with the Pi (I need an analog pin to expand of course) so a new chop will need to be ordered.

    Not to worry though, as my expander chips will be getting put to use with an Arduino Pro Micro to make a simple electronic drum brain.

  • Finally, a build update

    Craig Hissett03/01/2019 at 01:27 0 comments

    Sorry for the long delay between updates folks.

    Build update :- I am currently working on building a little enclosure to house my Pi and the 5 switches. I have a few analog expander chips on the way, which I will use to add a potentiometer to my inputs to simulate an expression pedal.

    Today i have also ordered an audioinjector soundcard for my Pi:

    I really wanted to make my pedal all inclusive, and plugging in a USB interface to handle audio, well, it sucked.

    This soundcard will go onto my Pi, connects via SPI (leaving all my gpio pins used fornbutton handling completely free for that job) and is already supported in the Linux kernel so it shouldn't take a while lot of work to have it working with JACK.

    I'm feeling good about this build ; once my parts arrive Ibshould be able to finally build it, and for once it'll actually match what I had in my head when I first set out to build it.

  • It's alive!

    Craig Hissett02/18/2019 at 01:56 0 comments

    It's 1:55am, but I finally have some good progress to report!

    I've managed to get a few buttons connected directly to the Pi to pass MIDI instructions to the MODEP software.

    This is handled by a Python script on startup, opening a virtual MIDI port for the script to send commands.

    It works great with the software, and it's really easy to set up a control to be handled by the physical buttons.

    I've also tweaked the Jack server running on the device, reducing the issues ideas having with sound quality dramatically.

    Next step is to add a few more buttons and an encoder or two into the script, and prepare for an analog expander chip that's on its way. This will read potentiometer values from expression pedals.

    I also want to build a nice case to put this in too :)


  • Progress

    Craig Hissett01/29/2019 at 23:35 0 comments

    It's been a while, but I have finally got around to doing a little more on this project.

    Hardware - I have decided to switch out my footswitch for an off the shelf Line6 FB4. It looks smarter, is smaller, and will be more reliable in the long run.

    Tomorrow I will solder up an Ethernet breakout cable to allow me to use the FB4 with the Arduino Pro Micro.

    Software - I did a bit of tweaking to the jack config, and it already seems a whole lot more reliable!


  • Hmmm... Noisy

    Craig Hissett12/04/2018 at 21:17 0 comments

    I got to give my board a go today  and had mixed results.

    The board worked, however there appeared to be a lot of digital noise in my headphones.

    I'm going to do some trouble shooting and see if I can isolate the problem, as it could be an issue with my interface.

    The footswitch is an old project that I'm hoping to use as a stopgap while testing my board. Hopefully it'll be working over the next few days too.

  • A Case for the pedal

    Craig Hissett11/24/2018 at 01:37 0 comments

    I have an old Stagg case that I used to keep a some guitar stuff in.

    Its ideal for this build; the hinges separate, meaning I can build my project into the lid and just remove the rest of the case for use.

    This pic shows the Pi and interface in there, with an Arduino Pro Micro breadboard set up to test a 5 button, 2 potentiometer midi interface.

    Once I've got a script that will work with the software I'll build a footswitch into the case.

    The Pi and Arduino will be inside the footswitch, and the interface with be countersunk into the top of the angled switch. The space on the right of the picture will be where I build an expression pedal.

  • Software Success!

    Craig Hissett11/23/2018 at 00:53 0 comments

    Tonight I managed to get my Pi software configured and loading with my audio interface. Good times!

    Tomorrow at a more appropriate hour I shall put together a sample effects chain and test out latency and adjust following testing.

    After that - footswitch building and mounting in its case.

    Until then, here's the interface on my phone:)

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castvee8 wrote 04/04/2019 at 15:30 point

Nice project Craig! got one going myself again this year. hope you do well.

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Craig Hissett wrote 04/04/2019 at 19:59 point

Thanks mate! The project is shaping up nicely; just a few cables to solder, holes to cut, then a new case to be built :)

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