INTRODUCTION TO SYNTHESIZERS - hol.gr

Today sampling technology is used in nearly every personal computer, and a sampling instrument is no more
expensive than a regular synthesizer. In computer terminology, sampling is sometimes (slightly incorrectly)
referred to as "wavetable synthesis".
A normal desktop computer with a decent 16-bit soundcard can do everything that a dedicated sampling musical
instrument can - and even with better sound quality, more functions and greater ease of use.
All that's required is some software to put this technology to work. Sampling software exists in many different
forms and shapes today, but one of the coolest software-based sampling instruments available today is the
awesome GigaSampler from NemeSys.
GigaSampler 1.5
Click on the icon to listen to the
GigaSampler!
(Miroslav Vitous Symphonic Orchestra
sample library)
(349 kB)
The theory behind sampling is the same regardless of if we are using dedicated samplers or soundcards in a PC,
so let us just focus on that for now. We mentioned that sampling works by measuring the incoming waveform
with regular intervals and storing these numbers in memory. Let's look at sampling in more detail!
Sampling frequency
The sampling circuit performs the task of analyzing the incoming sound wave and chopping it up into tiny
pieces. This part of the sampler is usually called the "analog-to-digital converter", or A/D converter for short.
This circuit is controlled by a built-in "clock". For each tick of this clock, the waveform is measured, or sampled.
To make a good recording, the clock must be ticking very fast indeed - we actually need to sample the incoming
waveform at least 40 000 times each second!
If we would sample the wave with longer intervals, we would simply miss too much of the waveform's
characteristics between the sample points to be able to make a clear reproduction.
The number of measurements each second is called sampling frequency, or sampling rate. Let us visualize the
sampling process:
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