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

View all 8 components

  • MkII Underway

    Craig Hissett12/18/2020 at 21:16 0 comments

    So, the next version is being built :-)

    The first one was great, but my setup would suit more buttons and inputs than the first allowed.

    The new plan is to use a Pisound soundcard on a Pi4 4gb, and to create a midi controller separately in a modular build in a small pedalboard.

    So far the Pisound has been acquired, as has some Arduino midi bits and bobs to try some plans out.

    My IO needs need to be thought out fully, but so far I know I need:

    Minimum 5 footswitches - for controlling 5 effects.

    2-3 encoders per footswitch - to assign parameters to.

    2 footswitches for cycling up and down patches.

    I2c display for information (I'm feeling a Nextion display)

    Two tea jack sockets for expression pedal inputs.

    The Pisound has MIDI ports on it so I could use either a midi shield on a normal Arduino, or use a Due/Leonardo/Pro Micro w/expander for a native USB MIDI input.

    Enclosure plans are still up in the air; I have a standalone case for the Pi and Pisound, and I'm split between going for a large enclosure to house them all, a medium enclosure for just the MIDI controller, or a few small stompox pedal boxes daisychained together to look like an old school pedalboard.

    Either way, this is going to be fun!

  • Boom! Wired up and ready to test!

    Craig Hissett09/16/2020 at 20:45 0 comments

    It's taken a lot longer than I thought, but it's is now ready to test.

    There has been some issues to address in the assembly:

    Power supply - the power supply I had for this simply didn't fit one the buttons were in place. A 5V 3A phone charger was shelled and used instead.

    Pi orientation - the aim was to have the usb ports poking out the back of the case, with the board munted upside down, but the dimensions of the hat made this undoable. The usb ports aren't needed, so it's not a huge loss.

    Lastly I'd imagine some shielding will be needed to reduce interference, so on the lookout for some pretty shielding suggestions ha ha!

  • Wiring is underway

    Craig Hissett02/17/2020 at 17:11 0 comments

    Finally! The beast is being wired up!

  • Enclosure Update

    Craig Hissett10/10/2019 at 20:14 0 comments

    Case assembled, sockets in place.

    Next step is to mount the 50w power supply, add the Pi on standoffs and then wire this little beauty up.

  • Another piece of the acrylic puzzle

    Craig Hissett10/03/2019 at 21:36 0 comments

    The top panel has now been machined 😎

  • Enclosure

    Craig Hissett06/23/2019 at 06:49 0 comments

  • Progress update

    Craig Hissett06/10/2019 at 16:31 0 comments

    Apologies for the lack of updates on this bad boy - progress is still slowly ticking away in the background!

    I'm currently fixing some issues in the software at present; upgrading everything to allow the use of the AudioInjector card has broken my WiFi, unfortunately. I've slowly getting to the the bottom of it, but it has been a time consuming and frustrating affair.

    I have also been doing some work on the Wah/Expression Pedal input; rather than sticking an arduino in and plugging it in I am tempted to experiment with an ESP8266 to send data wirelessly.

    I already have a python script translating GPIO pin button presses into MIDI, so adding some further code in there to translate incoming data is entirely plausible.

  • 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.

View all 27 project logs

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Tim wrote 02/04/2020 at 13:47 point

Is the alesis io2 required for this project or is there a cheaper way to make it?

  Are you sure? yes | no

Craig Hissett wrote 02/17/2020 at 17:02 point

Sorry for the late reply buddy, didn't get a notification of your comment!

The io2 isn't required, although some kind of interface is needed really to get a decent sound quality and low latency. I ended up going for the AudioInjector Soundcard, which cost around £30 including shipping from Australia. It takes a while to arrive, but it is a great card!

  Are you sure? yes | no

Al Ingham wrote 12/23/2019 at 04:06 point

I’m really interested to see what sounds you can get out of this. I’ve been looking at a range of multi effects pedals in the last week, and am gobsmacked at the prices! I guess you pay for what you get, but really... how hard can it be to build your own?!!

  Are you sure? yes | no

Craig Hissett wrote 02/17/2020 at 17:10 point

Hi Al! Yeah multi effects can be extremely expensive! The best multi effect pedal I owned was the Yamaha Magicstomp, which is a bloody brilliant unit. The software to edit your own patches takes a while to get used to, but there wasn't a single sound I couldn't get from it with a bit of time.

The software I'm running on this is the open source software that runs on the MOD Duo pedal (an effing fantastic, but a bit costly unit), and it is great; everything is drag and drop, and the routing options for the signal path is so versatile.

I've already planned my next 'pedal'; a modular setup using an intel-NUC sized PC and an arduino Mega-based board kitted out with dozens of buttons, screens and encoders and displays to be enable to fully take advantage of the software's ability to create massive boards.

  Are you sure? yes | no

Paul Burford wrote 09/08/2019 at 16:23 point

Hi Craig! After recently mentioning my guitar Arduino controlled valve amp, thought I'd send you a link to it. I haven't uploaded all the info but it's getting there.

Any news on the effects unit?

  Are you sure? yes | no

Craig Hissett wrote 02/17/2020 at 17:04 point

Hello matey! Wiring is underway, and some videos will be up in the next couple of weeks. I'm not the best guitarist, so my band's guitarist is going to put it through it's paces. Then, I'll be putting a vocal mic through it and using it with my trombone :)

  Are you sure? yes | no

tom wrote 06/17/2019 at 22:31 point

Inspiring project.  I'd like to build one myself.  Can you tell us why you went with the AudioInjector board vs the PiSound?  

  Are you sure? yes | no

Craig Hissett wrote 06/18/2019 at 16:29 point

Thanks Tom.

The main reason for going for the AudioInjector was intrigue; I was fascinated to see what the interface could do for such a low price. The PiSound boards are great, but are quite expensive and without any real funds to throw at this I had to go cheap :)

In addition to cost I always had a vision of wanting to piece together my own pedal layout, using multiple buttons, encoder, screens etc so going with a generic card is handy.

  Are you sure? yes | no

tom wrote 06/18/2019 at 16:34 point

Price I can definitely understand.  Are you saying that Audioinjector allows you to use the GPIO pins where the PiSound doesn't?  Is there a difference in latency between the 2 audio cards?

  Are you sure? yes | no

Craig Hissett wrote 06/18/2019 at 17:31 point

The Audioinjector has all pins passed through, so it makes it easy to expand. 

As far as latency is concerned I haven't yet put it through it's paces properly but the Audioinjector forums look very promising with the performance.

It should handle the processing for the guitar software perfectly :)

  Are you sure? yes | no

tom wrote 06/18/2019 at 17:58 point

Thanks for the info.  Please let us know how it goes!  

  Are you sure? yes | no

tom wrote 06/18/2019 at 19:12 point

Sounds like you are trying to avoid adding MIDI to this project so you can roll your own buttons/pots w/ the GPIO?  Keeps it simple, though then you have to handle sampling the buttons/pots in RPI side of things?

  Are you sure? yes | no

Craig Hissett wrote 06/18/2019 at 19:21 point

Yes and no ;)

While there's no actual ports for it yet, MIDI is still an important part of this build; my python script that reads the buttons created a virtual MIDI port and sends MIDI commands when the buttons are pressed.

This will allow me to add more devices (via i2c, serial etc) and easily integrate them with a slight adjustment of the python script.

I'm also looking at a wireless expression pedal for this, having an esp8266 and a 9v battery read the potentiometer of a way pedal and use the python script to interpret that too.

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[this comment has been deleted]

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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