Kurzweil update rate, MIDI Tuning Dump Standard

> The problem is also made more difficult by the fact that at least some
> synths, Kurzweils included according to a K2500-user friend of mine,
> service everything but note events only on a moderate-frequency interrupt
> basis. The result is that you can have an unknown or semirandom amount
of
> time from note-on to pitch-bend.
>
The Kurzweil K2000 and K2500 update low level parameters at a 50 Hz rate,
which is every 20 ms. Most other synths probably update at about half that
rate. For that short a duration I doubt you'd hear anything unless the
pitch
bend was 50 cents or more.
>
> Beware that Pitch Palette does NOT support the MIDI Tuning Dump standard
per
> se! The standard is too slow for the on-the-fly retuning that their
program
> does. To retune takes 408 bytes or about 130 ms. which is much too slow.
I
> asked them about the Ensoniq MR rack which they do support. It retunes
via
> the MIDI Tuning Dump. Ensoniq in their superior wisdom designed the MR
> series with a shortcut mode where you need only send one octave worth of
> tuning data, 50 bytes or about 16 ms. Great, for octave repeating
tunings.
>
> Even the MIDI Real Time Single-Note Tuning Change takes 8 bytes plus 4
bytes
> multiplied by the number of notes to be changed. This might work but the
> program would have the added complexity of having to select which notes
need
> to be retuned first in the context of the music.
>
> I went through all the trouble of looking for a sound card (Turtle Beach
> Tropez+) that supports the MIDI Tuning Dump standard only to find that
the
> standard is flawed for many applications. Or is it MIDI in general that
is
> flawed for microtonal applications?
>

The MIDI Tuning Dump standard certainly has deficiences, probably because
not many people contributed to its conception.

The greatest limitation is the insistance on handling tuning dumps
only on a full keyboard basis. This makes dynamic tuning programs
like Justonic's almost impossible as the MIDI bandwidth can't
support real-time updates.

The other problem is the immediate updating of sustained notes.
This is also a problem for real-time key modulations, especially
for rapid paced music.

One thing I've seen mentioned is the desire for tuning of better
than 1 cent resolution. Manufacturers are not likely to incorporate
such a feature, not because it is too expensive (it requires 4-8 bits
more resolution in the oscillator/accumulator and any associated
registers, something that would be almost trivial to add), but rather
because all samplers and sample playback based synthesizers
are lucky if their samples are tuned to better accuracy than this.

This wouldn't be a problem in a non-sample based instrument. But
most of the newer DSP-based analog modeling synthesizers are
retro in one additional way -- they don't include tuning tables. The
only exception is the Korg Prophecy.

John Loffink




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