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TUNING digest 876

🔗john_loffink@ycrdi.com

10/28/1996 10:26:14 AM
Gary Morrison writes:

> As I recall, and I'm quoting this from a friend who owns a K2500, the
>limitations are:
>1. You can tune "any" equal-temperament across all keys linearly (that is
some
> completely consistent number of cents between each adjacent key up the
> keyboard). The problem is that you only can do that to 2-cent
resolution.
> Quartertones (50 cents per step) therefore work fine, but 19TET (approx.
> 63.16 cents per step) doesn't.

You can do any equal tempered scale including Carlos style alpha, beta and
gamma non-octave repeating scales by using KEYMAP tuning in combination with
finer PITCH modulation. For 19 tone equal temperament, set the KEYMAP Key
tracking to 64 cents per key. That leaves an additional -.84 cents per step
to be detuned. Go to the PITCH menu page, set source 1 to BKeyNum (a
parameter that tracks the MIDI key number from -1 at MIDI key #0 to 0 at MIDI
key #64 to +1 at MIDI key #127) and set the depth to -.84 x 128 steps =
-107.52. The closest value you can select is -110 cents on the K2x00. This
gives a tuning accuracy of (110 - 107.52) / 2 = 1.24 cents over the entire
MIDI note range. Finer accuracy can be achieved by using modulation source 2
or one of the four functions available per layer.

Actually, the key tracking resolution for KEYMAP varies, from 1 cent near 100
cent/key tracking to 5 cents and worse the further you get away from 12TET.
But using additional pitch modulation can overcome that limitation.

>2. You can retune the notes of the keyboard to arbitrary pitches with a
key-
> map. The problem is that you're limited to 12-tone-per-octave tunings.

> Again 19TET in the frequently-used "linear" mapping of 63.16 cents
between
> adjacent key is not possible. That limitation does make it possible to
> map it into two-or-more 12-toned subsets, like I did in my EPS
Xenharmonic
> Scales Disk (one with naturals and flats, one with naturals and sharps,
and
> a third with the most common accidentals (e.g., F# instead of Gb, and Bb
> instead of A#) along with E#/Fb and B#/Cb). I don't know if the K2x00
> provides any means like the EPS/ASR's patch-select buttons of
> interactively switching between tuning tables though.

You can interactively select the intonation tables by using the Data Entry
Alpha Wheel or the Plus/Minus buttons while you have the Master Page
Intonation Table selection parameter highlighted. This works realtime
without glitching. It's also a short 9 byte sysex message to achieve this
from your sequencer. These changes would take effect globally rather than
per instrument as on the EPS series.

> The rather cumbersome solution is to turn each key into its own
individual
>sample playback, and adjust the pitch of each accordingly. There is
apparently
>a program that helps you do that.

I've never heard of such a beast. It wouldn't work on the K2500 which has
different sysex than the K2000. I agree, by the way, this method is VERY
cumbersome.




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