Martin Robinson lives in the Scottish Highlands and is passionate about the great outdoors and tinkering with musical electronics. In this post he talks us through his experience of working with Bela to create an amazing sounding guitar effects pedal, all housed in a Corn Flakes box.

Pure Data: A Community Affair

I started dabbling with Pure Data a while back and the things the user community create and share with each other, combined with the help that everyone offers in the community make it a simply awesome programming language. There are some very clever folks out there! It’s great to become part of that community and to see some of my ideas and patches being used out there by other musicians. Inspiration for a few of the patches which made it onto the pedal came from PatchStorage, an incredible repository of Pure Data patches and projects in many other programming languages.

I started off experimenting with chunks of other people’s code and the Pure Data core examples and built new things from there. As I gradually became more ambitious I started getting these patches to work with different bits of hardware. I also started using FAUST, mainly exporting FAUST core library code as Pure Data externals. These externals then became parts of a jigsaw which I put together with other Pure Data objects for control. I also want to explore how FAUST works directly with Bela for future projects as I’ve only had Bela for a few weeks.

Variety Box Mk1

What I really liked about the Bela Mini was that I can create an effects box which I can quickly put patches on, and not take up too much desk space at all. The biggest surprise was just how quickly this was achieved as Pure Data patches can literally be dropped onto the Bela IDE. Great tutorials and knowing there’s support available on the community forum meant I got Variety Box Mk1 up and running in a few days. It currently sounds like this:

Mk1 suffered from a structure which was too weak for a stompbox, so Mk2 was created adding a bit of balsa round the edges and upgrading the screen size for my old eyes. This is Mk2 before shutting the lid:

The Variety Box uses a “Switchboard” PD patch to control the knobs, switches and screens which I can adjust for each patch. I also added a few commands to the OLED Screen example code so I can put stuff on screen where I want. Finally the Pure Data patches are running as the core of the audio effects. All schematics and code can be found on my github here: https://github.com/donnerbono/varietybox

The 4 initial patches you will find in the above repo are:

• Greyhole, using a FAUST library reverb patch which sounds immense!
• Multipack, basic chorus, phaser and left and right channel delays
• Charlie Bucket, bucket style delay with downsampling and a spring style reverb all taken from the Pure Data community
• Delay Arpeggiator / Sequencer. 4 steps of delay that can be time and pitch controlled.

Nothing here will be exemplar code as I’m not a developer, I just like having fun playing around with things and still have lots to look at even in these 4 patches. That said I am very chuffed getting ipoke finally working (thanks to Guilio’s guide!) and I think the Delay Arp Sequencer is pretty cool! To round things up here’s a track which has the pedal in action:

About Martin Robinson

Martin Robinson lives in the Scottish Highlands and when he isn’t out with his dogs or running around in the fresh air he plays around with guitars and musical electronics. He increasingly finds it’s more fun creating synths and effects that he can change and adapt himself (plus he’s not very good at reading other people’s manuals).

He also makes some songs as Pleasant Ditch when he stops fiddling with things and presses record: https://pleasantditch.bandcamp.com/.