New Gadget Madly In Hope

A blog about my iPhone dev efforts

28 March

PolyHarp is coming

PolyHarp is an extended chorded zither-like instrument that runs on the iPad.

It's related to LYR which I wrote for the Amiga before you were born.

PolyHarp's new idea is that the chords create the strings, so you can have a chord set based in any key, and have any intervals in any chord based off any interval.
These base frequencies are specified as standard note names like C#4 or as Hertz. All the intervals follow Droneo's interval specification format, so you can say 4/3, 762 (cents), 5:19 (5th degree of 19-TET) and 7:11@3/2 (7th degree of 11 equal divisions of a 3/2). I also added presets for standard intervals like II, VIIb IV# ,Ib, so you can build some standard chord sets. In fact, you build chord bars using that syntax or using a tone spire like Droneo's

PolyHarp can be subtractive (damping) or additive (undamping) . Damping means pushing a chord bar button damps the strings that aren't in the chord. Pushing two bars results in fewer "live" strings. Additive (undamping) system works the other way, the strings are normally all dumped and more are activated by pushing the bars. That way, you build up chords with multiple chords bars. There are also lock bars , which lock themselves as if pressed, and there are hammers which play all the strings when you press it. The felts, by the way, are just manipulating the 'damping" of the string, and so you can have "bad" felts that damp more slowly than "good" felts. You can also have the option of being able to excite damped strings on a strum, so it has that classic 'washboard-y' sound.

PolyHarp has an extremely simple oscillator structure so that it can be polyphonic (about 50 voices at 44.1KHz) It's a sine that get's clipped a little, with an envelope of paired decays. Very simple. There will be some kind of MIDI support - although I'm not sure the microtonal pitches will be supported.

PoyHarp will also have LYR's "strum Sequencer" which lets you build a strumming pattern independent of a chord pattern. PolyHarp attaches to AudioBus.

The layout of buttons and strings is pretty flexible: you can specify the location of the buttons and the size of the string area and they can be moved so they fit your hand better. I hope to get it out in a few weeks - it's already pretty exciting!

00:32:16 - jhhlnet - No comments yet, click here to add one