APPENDIX 1 - K150FS SYSTEM EXCLUSIVE FORMATS
This section describes in detail the MIDI system exclusive message formats used by the K150FS and Sound Modeling
Program to exchange voice information. An additional document titled: K150FS Version 1.6 Software by Ralph Muha
describes additional system exclusive messages that are available for program dump and restore, master parameter block
(global parameters such as MIDI mode) dump and restore, and remote front panel operation. The K150 User’s Manual
describes general operating features of the K150 which are equally applicable to the K150FS.
1. DETAILED DESCRIPTION OF CONTOURED SOUND MODELING
Elsewhere in this manual is a generalized description of the Contoured Sound Modeling process used by the K150FS detailed
to the extent needed for effective use of the Sound Modeling Program (.S.M.P.). This section will detail the process to the
level needed for understanding the actual MIDI system exclusive messages used to represent sound models.
Sounds in the K150FS are actually a hierarchy of data structures as shown below:
PROGRAM
VOICE(S)
MODEL(S)
PARTIAL-PARAMETERS CONTOURS ATTACK-FUNCTION RELEASE-SLOPES
Programs are the highest level and consist of one or more Voices layered together. Voices are the basic sounds from the
user’s point of view and cover the full range of the keyboard. Voices usually consist of several Models each of which covers
a limited pitch range. Models are the basic sounds from the sound designer’s point of view and consist of Partial Parameters
and Contours which define the overall timbre, an Attack Function that modifies that timbre according to MIDI note-on
velocity, and Release Slopes that define the sound’s release. Each of these entities has a corresponding binary data structure
which is communicated via system exclusive messages. A bottom-up approach will be used in describing these structures.
1.1 PARTIAL PARAMETERS
A sound model may have from 1 to 64 partials (additive synthesis components). Partial parameters give information about
these partials as follows:
1.1.1 Partial Type
There are 4 types of partials available for constructing models. Relative partials are the most common. The frequency of a
relative partial is a MULTIPLE times the fundamental frequency of the note being played. This multiple may have a
fractional part and may be less than 1. Absolute partials are also available. The frequency of an absolute partial is a fixed
number of Hertz regardless of the note being played. Two types of noise partials are available, "low" and "high". Each
causes the partial hardware to scan through a short noise table the difference being in the table that is used.
1.1.2 Partial Frequency
Every partial has a frequency which is a 16-bit value. The frequencies of relative partials are given as a multiple of the
fundamental pitch being played. The frequencies of absolute partials are given as a multiple (much less than one) of the
highest frequency that can be produced. The frequency field of noise partials varies the scan rate through the noise tables and
thus varies the noise spectrum. The relation between noise "frequency" and the spectrum is extremely complex and best
determined by trial and error.
1.1.3 Optional Partial Flag
This flag marks the partial as being less important to the sound’s timbre than unmarked partials. In a playing situation that
calls for more notes than there are partials available (but still less than the 16-note limit), optional partials are not sounded.
Thus in voices that use many partials, one should attempt to mark the less important ones optional. When actual partial
stealing is required, the higher numbered partials of presently sounding notes are stolen first.
