<< Chapter < Page Chapter >> Page >
Learn about analog synthesizer modules, the foundation for synthesizers based on analog electronics technology. While analog synthesis has largely been replaced by digital techniques, the concepts associated with analog modular synthesis (oscillators, amplifiers, envelope generators, and patches) still form the basis for many digitalsynthesis algorithms.

Introduction

Analog synthesizers dominated music synthesis technology throughout all but the last 15 years of the 20th century. Early synthesizers were based on vacuum tubes or other electro-mechanical devices, and transistor technology entered the music scene during the early 1960s. Analog synthesizers produce sound waveforms as continuous voltages. Oscillators produce basic waveforms such as sinusoids, square waves, and triangle waves, much like a function generator in the electronics laboratory. These waveforms are shaped by time-varying amplifiers to emulate the characteristics of physical instruments, e.g., loud at the beginning transient of a note, softer during the sustained portion of the note.

You probably know that synthesizers defined many of the pop music styles of the 1970s. Watch (and listen!) to the screencast video in to learn more about some of the common synthesizer techniques. A real-time graphical signal analyzer is used to visualize the sounds so that you can better understand what you hear.

[video] Examples of analog synthesizer sounds, including visualization of waveform and frequency spectra

The history of electronic synthesizers is really fascinating. In particular, the following sites form an excellent starting point:

Analog synthesizer modules

Everything about an analog synthesizer is analog! For example, a keyboard-based synthesizer uses a control voltage (CV) to change the frequency of the oscillator; the oscillator is therefore called a voltage-controlled oscillator or VCO . The time-varying gain of an amplifier is also controlled by a CV, so the amplifier is called a voltage-controlled amplifier or VCA . The VCO and VCA are two of many types of synthesizer modules that can be interconnected (or patched together) in many different ways.

Take a look at the video in to find out why interconnected modules are called patches , and to learn how to put together a simple patch involving a VCO, VCA, envelope generator , and keyboard controller.

[video] Origins of the term "patch", and simple example of an analog synthesizer patch using a VCO, VCA, envelope generator, and keyboard

Analog synthesizer modules can be grouped into four categories: sources , processors , envelope generators , and controllers ; each of these is discussed in detail in the following sections.

Sources

Signal sources include the VCO and the noise generator. View the video in to learn more, then quiz yourself to check your understanding.

[video] VCO and noise generator signal sources

The amplitude of a VCO's waveform can be adjusted (true or false).

False

How does a VCO interpret its control voltage to produce a desired frequency?

One octave per volt

Which VCO has the richest harmonic content?

Square wave has highest amplitude harmonics, but contains odd harmonics only; triangle wave has the most harmonics (even and odd)

Processors

Signal processors include the ( VCA ) and the voltage-controlled filter ( VCF ). View the video in to learn more, then quiz yourself to check your understanding.

[video] VCA and VCF signal processors

How does a VCA interpret its control voltage to produce a desired gain?

Zero volts mean zero gain, one volt mean unit gain

What types of filter functions can be implemented by a VCF?

Lowpass, highpass, bandpass, etc.

What VCF filter parameters can be adjusted by control voltages?

Corner (cutoff) frequency, bandwidth, resonance frequency

Envelope generators

An envelope generator creates a CV to operate other voltage-controlled modules such as the VCA and VCF. View the video in to learn more about envelope generators, in particular why they are usually called an ADSR .

[video] Envelope generators, especially the ADSR-style envelope generator

What is the normal (un-triggered) output of an envelope generator?

Zero

What does the acronym ADSR mean?

Attack - Decay - Sustain - Release

Why is the exponential shape used for envelope generators?

Easy to produce with RC-networks; matches behavior of real instruments

Controllers

A controller creates a control voltage (CV) to operate other voltage-controlled modules such as the VCA and VCF. An interactive controller offers the musician direct and immediate control of the sound, such as a keyboard, knob, or slider. A programmed controller generates a control voltage in some pre-defined way, such as a low-frequency oscillator ( LFO ) to produce vibrato, and a sequencer to produce a repeating pattern of control voltages for the VCO. View the video in to learn more, and then quiz yourself to check your understanding.

[video] Controllers including keyboard, knobs and sliders, low-frequency oscillator (LFO), and sequencer

Which types of output voltages does a keyboard controller produce?

A control voltage to control the frequency of a VCO, and a gate voltage to control an envelope generator

What is the portamento effect, and how is it produced?

A portamento is a continuous frequency transition from one note to the next; instead of producing a step-change in the control voltage connected to the VCO, the keyboard produces a continuously-varying voltage from the starting note to the ending note

Which device would a keyboardist use to automatically play a repeating pattern of notes?

Sequencer

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Musical signal processing with labview -- analog synthesis and modular synthesizers. OpenStax CNX. Nov 07, 2007 Download for free at http://cnx.org/content/col10480/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Musical signal processing with labview -- analog synthesis and modular synthesizers' conversation and receive update notifications?

Ask