The usage of the 5 most important synthesis modules

1. Explain the usage of the 5 most
important synthesis modules:
Oscillator, Filter, Amplifier,
Envelope, and LFO.

2. Objectives
To understand the usage of the 5 most
important synthesis modules:-
 Oscillator
 Filter
 Amplifier
 Envelope
 LFO
My name is Subrina, originally from Singapore but currently
residing in Seattle, Washington State, USA. I decided to teach
this topic as I always feel that with every subject, understanding
the basics is crucial. Similarly in music production, it is essential to
understand the 5 most important synthesis modules before attempting
to manipulate these when working with the DAW.

3. 5 most important synthesis modules
Before we explore the 5 most important synthesis modules, let us first
look at an overview of subtractive synthesizer components:-

4. Oscillator
What is an oscillator?
 An oscillator generates the basic signal. This is usually a
waveform that is rich in harmonics. Many synthesizers
offer more than one oscillator.
 Will either be labeled as “osc” or oscillator.
 The audio signal of a synthesizer is generated by the
oscillator. Usually you would choose from a selection of
waveforms that contain differing types and varying
amounts (more or fewer) of harmonics. The level
relationships between the fundamental tone and the
harmonics of the chosen waveform are responsible for
the basic sound color or timbre.

5. Oscillator
Common synthesizer waveforms and their
characteristics are:-
 Sine Wave: Clean and clear-sounding, a sine wave contains no
harmonics but the first harmonic; in other words, it is the
fundamental tone. The sine wave—used standalone—can be used
to create “pure” sounds like whistles, the sound of wet fingers on
the rim of a glass, tuning forks, and so on.

6. Oscillator
 Sawtooth: Clear and bright-sounding, a sawtooth wave contains
both odd and even harmonics. It is ideal for the creation of string,
pad, bass, and brass sounds.

7. Oscillator
 Square and Pulse Waves: Hollow and woody-sounding, a square
wave can contain a wide range of odd harmonics. It is useful when
creating reed instruments, pads, and basses. It can also be used to
emulate kick drums, congas, tom-toms, and other percussive
instruments—often blended with another oscillator waveform, such
as noise.

8. Oscillator
 The square wave can be reshaped to make the waveform cycles—or
pulses—more rectangular on many synthesizers, using a pulse
width modulation (PWM) control. The more rectangular the wave
becomes, the more nasal it sounds. When modulated in this way,
the square wave is known as a pulse wave, and contains fewer
harmonics. It can be used for reeds, basses, and brass sounds.

9. Oscillator
 Triangle: Like a square wave, a triangle wave contains only odd
harmonics. Because a triangle wave’s higher harmonics roll off
faster than the ones of a square wave, the triangle wave sounds
softer. It is ideal for creating flute sounds, pads, and vocal “oohs.”

10. Oscillator
 Noise: Pink/Red, Blue, White: Noise is useful for emulating
percussive sounds, such as snare drums, or wind and surf sounds,
among others.
-White noise: The most common noise waveform found on
synthesizers. White noise contains all frequencies—at full level—
around a center frequency.

11. Oscillator
-Pink and red noise: These noise colors also contain all frequencies, but
they are not at full level across the frequency spectrum. Pink noise
decreases the level by 3 dB per octave (of higher frequencies). Red
noise decreases the level by 6 dB per octave.
-Blue noise: Blue noise, which is the reverse of pink noise, increases
the level of all frequencies in higher octaves by 3 dB.

12. Filter
What is the filter and what is its purpose?
 Used to alter the basic signal by filtering out (removing) portions of the
frequency spectrum. Many synthesizers offer a single filter, which is
applied universally to all oscillator signals. Multioscillator synthesizers can
provide multiple filters, allowing each oscillator signal to be filtered in a
different way.
 The purpose of the filter in a subtractive synthesizer is to remove portions
of the signal—the frequency spectrum—that is sent from the oscillators.
After being filtered, a brilliant-sounding sawtooth wave can become a
smooth, warm sound without sharp treble.
 The filter sections of most subtractive synthesizers contain two primary
controls known as cutoff frequency—often simply called cutoff—
and resonance. Other filter parameters can include drive and slope. The
filter section of most synthesizers can be modulated by envelopes, LFOs,
the keyboard, or other controls such as the modulation wheel.

13. Filter
Types of filters:-
There are several filter types. Each has a different effect on various
portions of the frequency spectrum:
 Lowpass filter: Low frequencies
are passed; high frequencies are
attenuated.
 Highpass filter: High frequencies
are passed; low frequencies are
attenuated.
 Bandpass filter: Only frequencies
within a frequency band are
passed.
 Band Reject filter: Only
frequencies within a frequency
band are attenuated.
 Allpass filter: All frequencies in
the spectrum are passed, but the
phase of the output is modified

14. Filter
 Cutoff Frequency: The cutoff frequency, or cutoff, as the name
suggests, determines where the signal is cut off. Simpler
synthesizers offer only lowpass filters. Thus, if a signal contains
frequencies that range from 20 to 4000 Hz, and a cutoff frequency
is set at 2500 Hz, frequencies above 2500 Hz are filtered. The
lowpass filter allows frequencies below the cutoff point of 2500 Hz
to pass through, unaffected.

15. Filter
The figure below shows an overview of a sawtooth wave (A = 220 Hz).
The filter is open, with cutoff set to its maximum value. In other words,
this waveform is not being filtered.

16. Filter
The figure below shows a sawtooth wave with the filter cutoff set to
about a 50% value. This filter setting results in suppression of the
higher frequencies and a rounding of the edges of the sawtooth wave,
making it resemble a sine wave. Sonically, this setting makes the sound
Much softer and less brassy.
From this example, we can see that use of the filters to cut away
portions of the frequency spectrum alters the waveform’s shape, thus
changing the timbre of the sound.

17. Amplifier
What is the amplifier?
 Amplifier : Used to control the level of the signal over time.
The amplifier features a module known as an envelope, which
is broken down into several elements that provide level
control for the beginning, middle, and end portions of your
sound. Simple synthesizers generally offer a single envelope,
which is used to control the oscillator (and filter) over time.
More complex synthesizers can feature multiple envelopes.

18. Envelope
 The amplifier module of a synthesizer is responsible for controlling
the level—or loudness—of the signal over time.
 To put this into a musical context, consider the sound of a violin,
which slowly ramps up to a peak—or maximum—level as the bow is
smoothly dragged across a string, is sustained for a period until the
bow is moved away from the string, and then cuts off abruptly. In
comparison, hitting a snare drum with a drumstick results in a very
fast peak level, with no sustain portion, and the sound immediately
dies out (although there will be an amount of decay, the time it
takes to fall from the peak level). As you can see, these two sounds
have very different characteristics over time.
 Synthesizers emulate these sonic characteristics by providing
control over different parts—the beginning, middle, and end—of a
sound’s level over time. This control is achieved with a component
called an envelope generator.

19. Envelope
 The Attack, Decay, Sustain, and Release (ADSR) Envelope Controls:
An oscillogram of a percussive tone is shown below in which the
level rises immediately to the top of its range and then decays. If
you drew a box around the upper half of the oscillogram, you could
consider it the “envelope” of the sound—an image of the level as a
function of time. It is the function of the envelope generator to set
the shape of this envelope.

20. Envelope
The envelope generator usually features four controls—attack, decay,
sustain and release, commonly abbreviated as ADSR.
 Attack: Controls the time it takes for the initial slide from an amplitude of
zero to 100% (full amplitude).
 Decay: Determines the time taken for the subsequent fall from 100%
amplitude to the designated sustain level.
 Sustain: Sets the steady amplitude level produced when a key is held
down.
 Release: Sets the time it takes for the sound to decay from the sustain
level to an amplitude of zero when the key is released.
If a key is released during the attack or decay stage, the sustain phase is
usually skipped. A sustain level of zero will produce a piano-like—or
percussive—envelope, with no continuous steady level, even when a key is
held.

21. LFO
What is LFO?
 A low frequency oscillator, or LFO, is an oscillator designed to
produce signals whose frequency is at the bottom of, or below, the
audio range. Nearly all synthesizers have at least one LFO or a
digital equivalent. It is useful for producing a repeating control signal
for a wide variety of purposes; when added to the control input of
a VCO it produces the effect known as vibrato, and if it is added to
the control signal of a VCA, it produces tremolo. A typical LFO can
generate variety of useful waveforms including sine, triangle, square,
ramp-up, and ramp down. The most useful LFOs have an upper
frequency limit above 100 Hz and a lower limit below 1 Hz (such
frequencies may be given as seconds/cycle; for instance, a frequency
of 20 seconds/cycle corresponds to 0.05 Hz). An LFO may or may not
have voltage control over its frequency or other wave parameters; an
LFO with voltage control over the frequency is sometimes referred to
as a "VCLFO".

22. Thank you for taking the time to read through
the contents of my presentation. I certainly
hope you have learnt as much as I have and that
you will utilize information here for your future
music projects. Good luck!