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Appendix
Synthesizer Basics
If you are new to synthesizers, you should read this chapter.
It covers important facts about the synthesizer and explains the difference between
analog, digital, and virtual analog synthesizers. Important synthesizer terms such as
cutoff, resonance, envelope, and waveform are also introduced.
Analog and Subtractive
An analog synthesizer signal is an electrical signal, measured in volts. To give you a
brief comparison with a technology you’re probably familiar with, have a look at
speakers. The speaker coils move when the voltage—amplified by a power amplifier
and output to the speaker—changes. When the voltage rises, the speaker coil moves
forward. If the voltage falls, the speaker coil moves backwards.
In a digital synthesizer, the signal flow is digital. Binary descriptions of the signal (a
string of zeros and ones) are fed from one algorithm to another. This is an important
distinction to make. It is not the signal itself that is fed from a virtual oscillator to a
virtual filter and so on.
A virtual analog synthesizer is a digital synthesizer which mimics the architecture,
features, and peculiarities of an analog synthesizer. It includes the front panel with all
controls, which provides direct access to all sound generation parameters.
Logic Express’s ES1 is an example of a virtual analog synthesizer. Its virtual signal flow is
as per that found in analog synthesizers. It includes some of the desirable
idiosyncrasies of particular analog circuits—in cases where they tend to sound nice,
such as high oscillator levels overdriving the filter. The ES1 also features a graphical
control surface on your computer screen. Its signal processing (those virtual oscillators
and so on) is performed by the central processing unit (CPU) of your computer.