The first part of the project that I’m tackling is the sequencers. I have hardware synths and a sampler, but I’m currently using a Boss drum machine for all my sequencer. It works but it’s a bit limited, and its interface is not very immediate.
The obvious choice for a DIY midi sequencer is something based on the MIDIBox platform. The platform is based around a Core board which includes an ARM processor and the relevant MIDI/USB ins and outs. It allows easy interfacing with custom control surfaces through a number of simple input/output modules, most of which can be daisy-chained. In addition to being a modular hardware system, it’s also a set of software components based on the FreeRTOS realtime operating system that allows easily writing MIDI controllers, processors, and sequencers in C. All source and hardware schematics are available under an open source license, although commerical use is prohibited.
What I’m specifically going to go for to begin with is the MIDIBox SeqV4L sequencer/MIDI looper, which is small and optimised for live usage. It’s basically 48 buttons, 16 corresponding to the steps of the sequencer and 32 to select functions, and 64 LEDs, 16 that show the current step when the sequence is running, and 48 to show which buttons are activated.
There’s a more fully-featured sequencer, which has two displays, rotary encoders, and a lot more buttons, but I prefer the V4L for its more immediate design. It only allows two tracks at a time and requires an external controller to enter MIDI notes, but on the other hand it’s cheap enough that you can just build more as needed. In its current state it’s not ideal for drums/single-shot sounds, but the software is shared with the larger sequencer, which has a nice drum track mode, and a drum mode is forthcoming in the V4L software.
I built my first V4L a few months ago. It was a fairly easy build, but I’m not too happy with the control surface. It uses small, cheap buttons, and I think the panel is a bit cramped. So my first project is to build a bigger front panel. I’ve scrounged some very decent Alps switches from old Apple Extended II keyboards that I’ll use. I’ve made my first experiments with printing caps on a 3D printer at my local hackerspace and early results are encouraging, though for producing larger quantities it might be more feasible to cast them.
The MIDIBox platform also includes a module for a digital-analogue audio converter, and there is an app that allows you to use it as a simple sampler. I’ll get back to this as a sampler is the next project I expect to tackle.