Pidaltrain: Live/Recording Pedalboard

A small pedalboard to enable home recording and performance during lockdown

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While the whole of the UK has been plunged into a state of lockdowns, live music and studio work has been nigh on non-existent. As with a lot of industries, music performers have resorted to recording and live streaming from home.
Now I am predominantly working from home in my day job I'd like to assemble a rig to allow me to allow play from home.

Project Requirements

In order to meet my ideas,

  • Record Audio
  • Offer onboard FX
  • Be small and portable
  • Flexible audio routing
  • Have an intuitive interface to control it all
  • Be built from already owned parts (as much as can be)

Record Audio

The Audio DAW Reaper has recently released a Pi-specific installer for the Pi2 board and upwards; using this DAW would be great (and more useful than something like Audacity). I have a Pi 3 and an official

Onboard FX

Following my work with my Multi FX Stomp Box project I've been fascinated with MODEP by Blokkas Labs for running a virtual pedalboard. I have since picked up a Pisound soundcard and a Pi4 4gb to run it on as an upgrade to my DIY built pedal, and would love to use it in this setup to handle sound processing. It's dual inputs and outputs give options (like a dedicated recording output and live output), and its MIDI ports open up the possibility of controlling presets from a central interface

Size and Portability

I have a small Pedaltrain Nano+ pedalboard I picked up a few years ago and did nothing with it. It has enough space to mount the two Pis and a small space for a control interface. Given the two Pi devices will be powered from 5v it's feasible to, in the future, look to creating a large batter bank from 18650 cells to power the whole board. 

Control Interface

For a control interface I'd like to assemble a small box to go between the two Pi boards to act as a midi controller for them both.

I believe using two Arduino Pro Micros will be the simplest way to connect the two Pis; one can handle the buttons for the pisound, and one can handle the buttons for Reaper.

For Reaper, I'd like to have some basic controls to select a track, arm it and trigger recording.

For the pi sound the ability to switch between pedalboard layouts and also toggle pedals in the layouts on and off would be great. I'd also like to break out the analog pins for using expression pedals, and also the i2c for adding further interfaces in the future.

Flexible Routing

This is an important part - being able to use it in various configurations will be very useful thing.

The board will have the following audio routes:

  • Pisound output to Reaper input (via USB soundcard) | Reaper output via Pi HAT
  • PiSound output to jack out for live playing to an amp or FOH.

This will allow the board to have a live output and a recording output too. The Pi HAT has a headphone out, so backing tracks can be listened to while recording.

It also makes it possible to have different effects on the live out and the recording.

The use of a USB soundcard on the reaper pi will make it easy to unplug it and run it to a different recording system for use in studios when lockdown situations change.

Pre-existing parts

Good thing Is I am a hoard of all things Pi and Arduino, so mot of this parts list I have to hand.

I will need to find a more suitable enclosure to build my control interface; the one I have doesn't fill the full space on the board and would be too small for footswitches.

  • 2 × Raspberry Pi 4 4gb One for the Pisound, one for Reaper
  • 1 × Pisound Soundcard
  • 1 × Official Pi Touchscreen For Reaper control
  • 1 × Pedaltrain Nano+ pedalboard To mount everything to
  • 1 × USB soundcard To record from the Pisound

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  • Reaper Test

    Craig Hissett04/01/2021 at 23:16 1 comment

    Today I tried out a cheap USB interface with my Reaper Pi, and it worked!

    It was a noisy affair, but that's down to it being a rubbish interface. Next step is to try out another interface with a better quality input/output and go from there.

    There is also a need to work on the footswitch underway, as a mouse and keyboard we're needed to get any kind of useful experience. Maybe trying VNC with a tablet will help.

  • Cyberdeck-style layout?

    Craig Hissett03/23/2021 at 11:58 0 comments

    I've spent far too long looking at Cyberdecks on HaD and Reddit, I think. It's influencing my decisions with projects like this. It's not a bad thing. Ha ha ha!

    One of the main issues I've had with this project is space utilisation; fitting two separate Pi systems and still having enough space for a foot controller with plenty of controls for the two systems.

    Cyberdecks always seem to have a screen mounted off-centre on the back of the keyboard, and it creates space for a fair sized keyboard input, so I'd like to explore the same here.

    To that end, I'd like to look into mounting the Pisound and a much bigger enclosure for footswitches for it, then look to mount the Pi touchscreen setup to the back of the pedalboard, using two bolts through the pedaltrain board and another two through the footswitch enclosure.

  • Control Interface

    Craig Hissett02/25/2021 at 23:21 0 comments

    This requires some planning out.

    Once I have mounted the Pi's to the pedalboard I need to measure the space left for the enclosure:

    Length: _______mm

    Width:   _______mm

    This will determine the amount of buttons and functions I can fit into the box.

    Reaper Pi - essential controls:

    Channel selection (two buttons? Or an encoder?)

    Arm track to record (button)

    Record / Stop (button) 

    Desirable: mute/solo/undo buttons. Could be added as held button press features.

    Pisound - essential controls:

    Pedalboard up/down (two buttons)

    3-4 effect switches (with LED feedback to show on/off)

    Analog inputs broken out to trs jack's for adding expression pedals.

    I2c breaking out for possible extension button boxes to be added.

    Research to be done:

    Gut instinct is to run two Arduino Pro Micros as co-processors for this to give two native USB ports out. One used as a usb midi input for the Pisound, and the other as a usb midi device for shortcuts in Reaper.

    I've picked up a Raspberry Pi Pico recently, and running Circuitpython on that also allows for native USB use. They're really cheap, so may also make for good choices for this.

    Other options: run a software serial port out to a hardware midi jack and send midi data to the Pisound via the midi jack, dropping the need for dual controllers.

    If there's going to be a network established between the two Raspberry Pi boards there's a shout for using an ESP8266/ESP32 board to send wireless MIDI, perhaps. 

    There's even a shout to use a Pi Zero in USB ethernet gadget mode to share one of the Pi's network connection.

  • Audio Routing options

    Craig Hissett02/25/2021 at 23:01 0 comments

    Just a quick think-out-loud segment, here.

    My current plan is to run mic/instrument into the Pisound, then split the stereo output into a direct mono out for live performance and the other mono out to the Reaper Pi; itself sporting a little usb interface to get the audio in. I have a JustBoom Amp/DAC HAT I could add to the Reaper Pi, to give me options of a decent headphone out for monitoring recording/playback tracks and some RCA outs and speaker connections some interesting use cases.

    Over on another forum I am tracking a thread discussing the possibily of capturing audio on the Pisound Pi itself; if this turns out fruitful there may be a good argument for running a network cable between the two Pi's and having a setup that allows for dragging clips from the Pisound into Reaper. This network connection would also allow for the Reaper Pi to open up the Pisound virtual pedalboard interface for on the fly configuration.

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