This document is a lesson on synthesizers for a music production course by Jan Zurcher. It explains the components and functionalities of synthesizers, including oscillators, filters, amplifiers, low frequency oscillators, and envelopes. Each section is essential for generating and modifying sound waves through electronic means.

1. Hi. My name is Jan Zurcher.
I’m a singer-songwriter living in a
small town called Friday Harbor, San
Juan Island, Washington
This lesson is for Week 6 of the
Introduction to Music Production
Course at Coursera.org.
The topic I have chosen to look at
this week is…

3. By definition, this is a device that generates and modifies sounds using
electronic means. In general, a synthesizer generates specified wave
forms and then alters them in a way that changes their frequency,
duration, intensity and/or timbre.
There are different forms of synthesis:
1. Subtractive – removes the unwanted parts of a signal (such as
removing overtones)
2. Additive – builds a new sound from a pure sine-wave tone
3. Sampling – digital recording of sounds that are then altered
What is a Synthesizer?

4. Given that synthesizers are designed to:
• generate sound waves;
• change their frequency (i.e., filter them);
• change their intensity (i.e., amplify them);
• change their duration (i.e., by altering their sound envelope); and,
• alter their timbre,
most synthesizers have sections to accomplish each of these tasks.
Lets take a look at where each of these sections is found on a simple
synthesizer.
The following screen shots show the ES1 Synthesizer found in Logic Express
9.0. This particular synthesizer has several sections but the focus will be on
the 5 main ones:
What is a Synthesizer?

5. Oscillator
What is a Synthesizer?

6. Filter
What is a Synthesizer?

7. Amplifier
What is a Synthesizer?

8. Low
Frequency
Oscillator
What is a Synthesizer?

9. Envelope
What is a Synthesizer?

10. An oscillator generates sound based on a particular
wave form. Common options include triangle, saw
tooth, square wave and sine waves.
On the right, you see the Oscillator section of the
ES1 oscillator. It has 4 main controls:
1. Wave Knob Primary Oscillator - allows you to
select the primary wave form for the signal.
2. Octave Selector - allows you to select the
octave used for the wave generated. Note that
these are in “feet”. They represent the length of
organ pipes – shorter pipes generate higher
pitched sounds and longer pipes lower ones.
3. Wave Knob Sub-Oscillator - allows you to
generate another wave two octaves below the
primary wave. If you only want the primary
wave, this can be turned off.
4. Mix – controls the volume balance between the
Oscillator and the Sub-Oscillator.
Oscillator

11. The filter is a critical part of any synthesizer.
This is how you shape the spectrum of the wave.
While there are additional controls on this
particular synthesizer the three that are
common to most synthesizers are
1. Low Pass Filter – this is the 24 dB filter. This
filter is used to cut the high frequencies
(brightness of the upper harmonics) off the
signal.
2. Cutoff – allows you to set the frequency at
which high frequencies will be cut
3. Resonance – boosts the frequencies right
around the cut-off frequency. For a subtle
effect, use a low setting. A very high setting
can cause the filter to produce an entirely
different sound.
Filter

12. The Amplifier on this synthesizer
allows you control over which
parts of the envelope the amplifier
will access and the intensity of that
affect.
In other words, it shapes the
volume of the sound.
Amplifier

13. Envelope
The Envelope section is used to control the
level of the sound over time.
There are 4 basic components to a sound
envelope:
1. Attack – the length of time it takes
from the start of the sound to reach
the desired level
2. Decay – the length of time it takes for
the sound to fall to the sustain level
3. Sustain – the level the sound will
maintain until the key is released
4. Release – the length of time for the
sound to fall from the sustain level to a
0 level.

14. The Low Frequency Oscillator operates at
frequencies below the normal range of hearing.
The output of the Low Frequency Oscillator
connects to the input of the Oscillator causing
the pitch to waver (usually by just a very small
amount. It is often used to create vibrato
effects.
The controls in this Low Frequency Oscillator
include:
1. Wave knob – allows you to select the wave
form for the oscillator which impacts the
colour of the sound.
2. Rate – allows you to control the frequency
of the oscillation from 0 (Direct Current) to
24.5 Hz.
Low Frequency Oscillator

15. This concludes our quick tour of a basic synthesizer. Any time
you start to work with a synthesizer you will likely find these 5
basic sections – usually in the same basic configuration.
Oscillator
Filter
Amplifier
Low
Frequency
Oscillator
Envelope