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The Boo Box by Ishmael Zghoul

Posted in Projects Instruments Hardware Installations

The Boo Box packs in a looper, FM oscillators, a granulator, filters and more into a stage ready instrument/effects box. This project was created by the musician and free improviser Ishmael Zghoul who explains all below.

Instruments for free improvisation

This instrument/effects box, which I call my Boo Box (from the film Hook), was an evolution of an earlier creation on the Axoloti platform. During the initial design stages, I had a few things in mind. I wanted a buffer/looper that was controllable through a midi foot controller, an analog joystick that was able to manipulate parameters via the x/y pots, and a few rows of potentiometers that would control other parameters that I could assign later on. I ended up adding a few digital buttons as well after tinkering with some patches and seeing how much room I had in the enclosure.

The hardware

Now on to the Bela. Since the Bela board has 8 analog inputs and I needed 15, I used the multiplexer capelet. After setting that up, I measured the size of the Bela and multiplexer plus a bit of buffer for the wires and pots and started researching enclosures. I went with a Hammond enclosure due to its simplicity (for the previous version I built a custom laser-cut enclosure, but that was a lot of work for me and with my level of experience so I went the lazier route this time).

Same thing with the jack and pot holes: I went panel mount usb jacks, so that I could just drill a hole and install. I had to use a stepped drill bit for the large size of the joystick hole. After measuring everything and double checking if everything fitted I drilled away and tightened it all up. To mount the Bela in the enclosure I went with velcro because it was simple and effective. After that it was just a question of lots of soldering and testing.

The patch

So what does the thing do? I guess before getting into that some background on my work would be helpful. I’m a cellist, guitarist, and improviser that works a lot with balancing electronic and acoustic sounds while performing and I wanted to design for that context. Here’s a track that shows the Boo Box in action:

In the Pure Data patch I run most of the time, there are a pair of FM oscillators that I use and manipulate in real time. There’s also a triggered buffer that I can record into, and trigger random rhythmic variations of. I also have a trigger that morphs that buffer into a kind of granular playback, plus a function that uses the input volume to trigger feedback bursts. Last but not least I also have a trigger that turns the FM oscillators into a morse code sounding thing using a sine wave as an envelope filter.

The Boo Box in Action

You can hear some more recent work where I use my ‘Boo Box’ all recorded during lockdown.

Ishmael Zghoul

If you’re interested in some of my other work you can find out more info here: There’s a lot of projects from all over the place including a hip-hop/funk/free jazz outfit, a math rock improvising trio, a bunch of different free jazz/improvised music projects, and an all electronic duo.

Ishmael Zghoul

Thanks and I hope this helps someone out if they’re starting off with Bela or thinking about it!


Bela is an open-source platform for ultra-low latency audio and sensor processing. Find out more on our website, buy Bela at our shop, follow us on twitter, instagram or join our community and discuss this post on our forum.

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