Today’s software instruments can quite easily play notes in any arbitrary tuning system that you might devise. But those of us who go in for this sort of thing soon confront a serious problem: The standard pattern of white and black keys found on just about all commercially available MIDI master keyboards is utterly inadequate for playing most alternate tunings.
As long as you’re content to limit yourself to 12 notes per octave, you can get along nicely with a standard MIDI keyboard. The moment you stray beyond the boundaries of this rather narrow conception of a scale, you’re in trouble. Fingering becomes a nightmare.
One of the better resources I’ve found is Starr Labs. I’ve ordered their Z-Board keyboard, and it should arrive next week. I was tempted to buy their U-648, but it’s more expensive. The Z-Board seems an effective compromise.
Coincidentally, this morning I got an email from a fellow named Bogdan Constantinescu, who is trying to round up 20 buyers to underwrite the cost of producing 20 keyboards of a new model called the Terpstra 280. If you’re considering acquiring this type of gear, you may want to check it out. I don’t know Bogdan personally, and I can’t vouch for the stability of this business enterprise, but the design looks good.
Hexagonal key layouts are employed in the Terpstra, the U-648, and the C-Thru Axis. The Z-Board, in contrast, uses a checkerboard grid. The jury is still out on which layout is better for a universal keyboard. Hexagons may be better if you want to be able to slide a fingertip from one key to the next, as there are more directly adjacent keys. But my suspicion is that the human brain has an easier time grasping chord and scale shapes on a square grid.
The Terpstra’s keys are in elevated tiers, so you would only be able to slide a finger down, not up. Nonetheless, I feel elevated tiers are a very desirable feature, because they provide better hand positioning and tactile feedback. I’m a bit skeptical of interfaces like the Madrona Labs Soundplane, which I haven’t played, and the Haken Continuum, which I have, because they provide less tactile feedback. The nerves of the fingertips are exquisitely sensitive, and for me, tactile feedback is more important than the ability to slide freely.