Why MIDI? (was Re: Why DIY? (was Re: [sdiy] Another new hard to find part....))

[Antti Huovilainen]

On Thu, 8 Jul 2004, cheater wrote:

> > damn, you mean you can turn a knob to say, 16bit resoloution?
> > I mean, in a 270degree turn of knob you can pick out value 43271?
> I sure can filter-sweep with infinite resolution. I can't do that with midi.

A lot of the steppiness has to do with poor implementations. For smooth
control, you want to use higher resolution internally and smooth the midi
input (basically lowpass filter it).

> > again, you really think you can hit keys with such accuracy that it needs
> > more than 7bits?
> I can bet Chopin could - and I can bet Keith Jarret can now.

IIRC 0.5dB was about the minimum volume change normal human can perceive.
Having 127 possible values would give a dynamic range of 64dB - quite a
lot. Of course velocity can control other things too, but the point stays.

> > fair point, but thats a limitation of the fact you're using a keyboard to
> > start, which implies 12 notes to an octave.
> Using a keyboard is a limitation of midi as well.
> It's like a vicious cycle.

This is IMO one of the main limitations of midi. It's only really good for
keyboard based instruments. Adaptations to other control interfaces
(guitar etc) are always more or less hacks.

> Besides: just about every synth has a clone of the moog vcf.

This I disagree with. On the analog side most synths used CEM filters
which are more or less like linearized OTA based four pole filters. On the
digital side people unfortunately speak of almost any cascaded four pole
filter as the "moog" filter, while in reality they are simply linear four
pole filters. If you want "real" moog filter - wait for my DAFX04 (oct)
paper.
And of course there are the Other filters. SVF as used in some Oberheims,
MS-20 style filters, Steiner etc. On digital side many synths use SVF or
normal 2nd order IIR filters.

Antti

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