DSP Functions
Introduction to Algorithm Programming
14-1
Chapter 14
DSP Functions
This chapter presents explanations of the DSP functions that can be inserted into the algorithms
in the Program Editor. As you configure each algorithm, the DSP functions you select
determine the type of synthesis you apply to your sounds. Deciding which algorithm to use
depends on what you want to do; there’s no hard and fast rule. If you want to create a classic
analog sound, for example, you’ll choose one of the algorithms containing one or more blocks
that can have filter functions assigned to them. If you want realtime panning effects, choose an
algorithm that includes the PANNER function in the F3 block. Your best approach is to study
the algorithm charts in the
Reference Guide
, and choose the algorithm that includes the functions
you want to work with.
Before we get to the explanations of the DSP functions, we’ve included a brief discussion of a
few general concepts of sound synthesis. This should help you understand the workings of the
DSP functions. We’ll refer to these concepts repeatedly as we go along.
Any single sound waveform is composed of numerous sine wave components, each at a
different frequency. These components are called partials. The lowest frequency is perceived by
the ear as the pitch of the sound, and is called the fundamental. The other components are
called harmonics. The relative amplitudes (volume) of each of the partials in a sound determine
its timbre, its most recognizable characteristic. When you think of the difference between the
sound of a piano and a saxophone, you’re thinking about their different timbres. A dull sound
has a strong fundamental and weak harmonics, while a bright sound has strong harmonics.
Sound synthesis can be most simply described as the manipulation of either the amplitude or
phase of one or more of the partials constituting a sound. The K2500’s various DSP functions
give you a variety of methods for manipulating those partials. We’ve grouped our explanations
of the DSP functions according to the types of specialized manipulation they enable you to
perform on a given sound. The categories are:
FILTERS
EQUALIZATION (EQ)
PITCH / AMPLITUDE / PAN POSITION
MIXERS
WAVEFORMS
ADDED WAVEFORMS
NON-LINEAR FUNCTIONS
WAVEFORMS WITH NON-LINEAR INPUTS
MIXERS WITH NON-LINEAR INPUTS
SYNCHRONIZING (HARD SYNC) FUNCTIONS
Introduction to Algorithm Programming
Programming the algorithms is a multi-step process. The first step is selecting an algorithm.
Changing the algorithm of an existing program’s layer is likely to alter the sound of the layer
dramatically. As a rule, then, you won’t want to change a layer’s algorithm unless you’re
building a sound from scratch. Furthermore, when you change a layer’s algorithm, the values
for each of the DSP functions within the algorithm may be set at non-musical values; you
should lower the K2500’s volume slider before changing algorithms.
Deciding which algorithm to use for a new sound is primarily a process of planning a layer’s
signal path through the sound engine. The real sound manipulation is done by the DSP
functions you insert into the algorithm. The algorithm simply lays a framework that
determines how the DSP functions interact.
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