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Table Of Contents
There are many other global controls found on different synthesizer models that have
an impact on your overall sound.
Other Synthesis Methods
There are many ways to create sounds, using different technologies and approaches to
synthesis. This section covers all the main methods, with reference to Logic Express
instruments where applicable.
Many of the outlined methods incorporate into their design at least some elements of
the subtractive synthesis approach covered earlier. The most common modern approach
is based on samples of real instruments and sounds.
Sample-Based Synthesis
Sample-based synthesis, which is sometimes known as Pulse Code Modulation (PCM), or
sampling and synthesis (S&S) synthesis, is differentiated from subtractive synthesis mainly
by the use of samples in place of oscillator waveforms.
The samples—digital recordings of existing sounds—are mapped across the keyboard.
Typically, each sample is mapped to a note in the center of a keyboard range that spans
5 or so notes that are unique to that sample. The reason for this range of 5 or so notes is
that samples tend to sound much less like the source sound if played more than a few
notes higher or lower than the original pitch—due to the relationship between the pitch
and playback speed of samples.
The pitch of each sample isn’t changed with a frequency control, unlike the oscillator
waveform of a synthesizer that is not sample based. Rather, a sample is played back at a
faster or slower speed to alter its pitch, which has a corresponding impact on the sample
playback time. For example, a sample played back at twice the speed requires half the
time to play through.
The EXS24 mkII is a sample player that can be used much like a sample-based synthesizer,
due to the subtractive synthesis facilities that it offers.
Popular instruments that use this synthesis approach include Korg’s M1, O1/W, and Triton;
the Roland JV/XP instruments; Yamahas Motif series; and many others.
367Appendix Synthesizer Basics