Drawbar Programming Basics
Theory
The key to understanding drawbar programming is to understand the use of
harmonics. Harmonics are the basis of complex sound generation, and are
present in almost every sound you hear.
The most basic sound is the pure sine wave. It consists of the “fundamental”
tone only. The fundamental is the base frequency of a pitch. For example, the
frequency of the A above middle C is 440 Hz.
The sound of a pure sine wave is not very interesting (although it can be used
for deep bass sounds). We can make the basic sound more interesting by
adding “harmonics” – frequencies that are related to the fundamental tone.
The “rst” harmonic is a tone one octave above the fundamental. By mixing
some of this rst harmonic with the fundamental, we get a brighter and more
complex sound.
Harmonics can be manipulated in two different ways: either by starting with
a simple tone and adding harmonics (additive synthesis), or by starting with
a complex sound and removing harmonics (subtractive synthesis). Most
synthesizers use subtractive synthesis to create sounds, but the B4 (and any
real tonewheel organ) uses additive synthesis to create its sound. This is one
of the reasons that tonewheel organs have a very different sound from their
synthesizer cousins.
There is a series of harmonics (called the natural harmonics) that are related
to the fundamental in a specic way. These harmonics, if mixed together, will
describe something like a sawtooth wave (a moderately buzzy sound). The
natural harmonics of middle C, for example, are:
The rst 8 harmonics of Middle C
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