Gordon Self's Custom Keyboard + TBX1

January 23, 2011

In March of 2009, I received a few questions by email concerning TBX1 from Gordon Self, who lives in Manchester, UK. A few months later, he ordered a unit. Fast-forward a year and a half later … an email appears in my inbox from Gordon, opening with the following annoucement: "I've at last managed to get my own microtonal keyboard built to go with the Tuning Box." This eye-popping photo was attached:

A 31-keys-per-octave custom keyboard! Well, congratulations were clearly in order, and an email exchanged ensued over the next month, through which Gordon told me a bit more about his project, and supplied more photos.

I thought it would be fun to devote some space here to what he's been up to, so I posed the following questions by email.

Q: How did you become interested in tuning?

I suppose I should start by admitting something of a missed opportunity! As a lifelong synth-head and fan of electronic music, I owned a microtonal synth (a Yamaha DX11) for 12 years before I finally got round to using its micro-tuning feature…

When creating a roaring drone sound using the granular synthesis software Crusher-X, for my piece Cathode, I wanted to use its oscillators but found that you had to set the pitch in hertz. It was much easier to use multiples of a starting frequency (harmonic series) than to calculate hertz values for the notes of the 12 equal temperament scale. I had so much fun with that, that I decided to do some proper research and find out how to get the same harmonic series on the DX11, so everything in Cathode would be in that tuning. [NOTE: You can hear a short clip of Cathode, Track 11 of Gordon's album "Compilation Zero" here.]

On the whole I'd describe my current listening (and composing) as a varying mixture of electronic, minimal and spectral… As my interest in modern classical music and acoustic instruments has continued to grow, I took up harp a few years ago. I've enjoyed the relatively simple microtonal work I've done with this instrument so far: even though it only has 7 strings per octave you can tune it to any temperament without making it harder to play. And as I'm totally studio-based I can re-tune it for different parts of the same piece of music.

Q: Can you tell me a little bit about your design and how you arrived at a 31 tone layout?

I like the fact that when you divide the octave into certain large numbers (31, 41, 53…) you can get major and minor scales that sound at least as consonant as the 12et we're all used to, while still benefitting from the compositional skills that you've learned in 12et. But you now have so much more freedom gradually to bring in more exotic intervals and chords, and to write melodies with steps smaller than conventional semitones. As a lot of my music is heavily chord-based, I'm hoping to learn how to combine the chord progressions successfully with microtones. Before I had a dedicated keyboard I started composing in 31et on the piano-roll of my MIDI/audio recording software, and I already started to find this tuning a very good trade-off between the new possibilities it offers and the moderate difficulty of working with the extra notes…

This key layout is partly inspired by the Fokker Organ and partly the Tonal Plexus. Fokker also used 31 notes per octave, but the diatonic scale runs diagonally across his keyboard, so to make it go horizontally from left to right I had to use staggered key columns like the Tonal Plexus. Sharps and flats are black; double sharps and flats are silver. The keys with green dots are the 12-note meantone scale - or at least a pretty good approximation of it; this should help me to compose for meantone instruments so that they can play a part in 31et music. The range of the whole thing is 126 notes or 4 octaves, and it doesn't sense velocity. The MIDI encoder circuit is from MIDI Gadgets Boutique. [NOTE: H-Pi Instruments PCBs are designed by MGB's chief engineer, Jordon Petkov.]

The keys are hinged from the top, piano-style, using microswitches. This, as I'd feared, is the weak point. The key action is rather light and noisy, and there's quite a bit of sideways slack in it too. It works for my purposes as a composing tool, but wouldn't be at all suitable for performance. To fit so many key columns into the space, they had to be quite narrow; that and the light springing means I keep pressing more keys than I meant to!

Q: You are using the keyboard with TBX1. Can you say a few words about how your setup works for you?

This keyboard is meant mainly for getting a feel for microtonal scales and trying out compositional ideas - my finished work is sequenced on the computer as it always has been (apart from the acoustic instruments and even there I use MIDI guide tracks). The Tuning Box allows me to use microtones on nicer-sounding synths than the DX11. I've been programming it with various other equal divisions of the octave that are specifically mapped to fit the key positions/colours of this keyboard. So far I've got 17, 19 and 29 (well written about on the H-Pi site) and the fascinatingly weird 22 (which Ivor Darreg used to recommend). 19 is particularly good on this keyboard because like 31 it's isomorphic - moving across the keyboard by the same distance/direction always gives you the same jump in pitch. Assigning these specially mapped scales to the TBX1's preset buttons means I've got all of them instantly available. I don't think these other scales will get as much use in my finished compositions, because they aren't as good for chords as 31, but they can be great fun to play around with.

Q: Now that you have a custom keyboard, what's next for you?

So far, 31et and the harmonic series are the only microtonal scales that I've used in finished pieces of music. I'm planning to put most of my effort into 31et for the moment. I hope to integrate it with my existing techniques - and start producing long multi-movement pieces in this tuning.

If I do build another keyboard, I'd like to find a better key action more like a computer keyboard, so that all parts of the key top respond equally to the right kind of pressure. For now though, I think this one will give me plenty to work with.

It's certainly not every day that someone designs and builds a custom microtonal keyboard; kudos again for what you've accomplished, Gordon, and thanks for sharing your work!