Pitch Bend Tuning

Friends,


I am attempting to use pitch bend messages sent by sequencer to a
K2000 to set frequency output to conform to JI ratios in a more perfect
fashion than possible using Global software tuning or other cent based
methods.

I sent the following message to the list last week:

> This is a rather basic question I know, but does anyone know what
>the tuning resolution of the K2000? How many steps are possible between a
>semitone, and if this number is something like 2048 or hopefully 4096, how
>are translations made between this number and cent values? Thanks in
>advance.

_______________________________________________________________________________

I recieved the following response from John at Kurweil:

If you're speaking in terms of the intonation tables, resolution is
limited to 1 cent steps by software. The value set in software is
truncated, not rounded, to the next lowest hardware resolution, which is on
the order of
1/20 cent. Transposing samples downwards 4-5 octaves or more reduces the
tuning resolution.

Changing pitch by other means such was the pitch wheel will usually
be more limited by the controller than the K2000 internals. Most if not
all of the
pitch wheels of current synthesizers have a resolution of only 7-8 bits, even
though the MIDI parameter has a resolution to 14 bits.

_______________________________________________________________________________


I still have several unanswered questions concerning generally
using the pitch benf message to control tuning, and more specifically doing
this on a K2000. Let me further clarify my query with the following
questions:

1) Where does the 1/20 of a cent figure come from? Does that mean
that there are 2000 (or probably 2048) possible frequency divisions between
a musical half step?

2) In the hypothetical scenario where the pitch bend range is set
to 100 cents under the "Common" page, and MIDI pitch bend messages are sent
using an external sequencer to produce every possible value in step size of
1 unit (0,1,2,3... ...8189,8190,8191) from 0 to 8191, how many unique
pitch values will the K2000 produce? Is it capable of producing 8192
unique values? Is the figure dependent upon the initial frequency of the
note?

3) Would I be correct in assuming that pitch bend messages affect
the absolute output frequency in an exponential fashion as in the 12Tet
model? What I mean is, if I played A440 and with a pitch bend value of 256
(and pitch bend range was set to 100 cents) would the output frequency in
Hertz be equal to 440((2^(1/12))^(256/8192))=440.7949Hz?


thanks...


-andrew

Safe Journey...



Received: from ns.ezh.nl [137.174.112.59] by vbv40.ezh.nl
with SMTP-OpenVMS via TCP/IP; Tue, 5 Nov 1996 03:16 +0100
Received: by ns.ezh.nl; (5.65v3.2/1.3/10May95) id AA05988; Sun, 3 Nov 1996 19:04:24 +0100
Received: from eartha.mills.edu by ns (smtpxd); id XA08809
Received: from by eartha.mills.edu via SMTP (940816.SGI.8.6.9/930416.SGI)
for id KAA08031; Sun, 3 Nov 1996 10:04:21 -0800
Date: Sun, 3 Nov 1996 10:04:21 -0800
Message-Id: <961103175928_71670.2576_HHB64-10@CompuServe.COM>
Errors-To: madole@ella.mills.edu
Reply-To: tuning@eartha.mills.edu
Originator: tuning@eartha.mills.edu
Sender: tuning@eartha.mills.edu