Kurzweil PC3A7 [78/423] Algorithm basics

Program Mode

The Algorithm (ALG) Page

6-23

Algorithm Basics

Each of the 59 available algorithms represents a preset signal path. With our new Dynamic VAST

feature, you can edit any preset signal path and make your own, unique algorithms, but that will

be explained further on in this section. Take a look at Algorithm 1 in the diagram below. It’s one

of the simplest algorithms.

The DSP functions are represented by the rectangular blocks. The lines connecting the blocks

together indicates the ow of the digital signal from left to right; they represent what we call the

“wire” of the algorithm: the actual physical path that the signal follows through the algorithm.

Selecting dierent algorithms can be compared to connecting dierent DSP functions with

dierent wiring diagrams.

Think of the left side of each block as its input, and the right side as its output. Depending on the

algorithm, the signal may split into two wires, enabling part of the signal to bypass certain

portions of the algorithm. Split wires may rejoin within the algorithm, or they may pass all the

way through as split signals. If the last block has two wires at its output, we call it a double-

output algorithm. If it has one wire, it’s a single-output algorithm, even if there are two wires in

earlier portions of the algorithm.

Each block of the algorithm represents a certain function in the signal path. In every non-

cascaded algorithm (see Alt Input for Algorithms (Cascade Mode) below), the signal ows rst

through a one-stage DSP function that controls the pitch of the samples in the keymap (this

function is represented as a block labeled PITCH in the upper right-hand corner of the display).

In fact, the rst DSP function in each algorithm always controls pitch, even though it doesn’t

apply in every instance and, as will be explained later in this section, it is bypassed in cascaded

algorithms. Similarly, the last DSP function always controls the nal amplitude of the signal (this

function is represented as a block labeled AMP in the upper right-hand corner of the display).

The number of function-parameters a DSP function can have depends on the relative size of its

function-block on the Algorithm page (four slots is the largest block size.) For instance, a

function-block that is three slots long can have up to three function-parameters, whereas a

function-block that is two slots long can have up to two function-parameters. For each function-

parameter, there’s a corresponding “subpage” on both the DSPCTL and DSPMOD pages. On the

DSPCTL subpages, there are neadjust and hard-wired parameters with which you can make xed

adjustments to the function-parameter. On the DSPMOD subpages, there are programmable

parameters that you can assign to any control source in the Controller List to modulate the

function-parameter. The above italicized parameter-types are described in Common DSP Control

Parameters on page 6-24. More information on the subpages can be found in The DSP Control

(DSPCTL) Page on page 6-29 and The DSP Modulation (DSPMOD) Page on page 6-30.

Highlighting any of the function-blocks on the ALG page and pressing the Edit button takes you

to the DSPCTL page.