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This article presents some of the pillars that sustain the world of electronic music. The first synthesizers were the elements that started the history of practical electronic music, there in the 1960s. Those were still rudimentary devices, built in external separate modules, that produced energic and rustic sounds. In the 1980s, the introduction in the market of a large number of technologies that were in experimentation during the previous decades, brought many new possibilities in the field of electronic music. In that decade appeared the MIDI protocol, software-based devices, digital synthesis, etc... Sequencers became omnipresent, so now electronic music could not only be performed in real time with hardware-based instruments, but also created as a product is built in a workshop, being possible to modify the composition innumerable times before being exposed to the public. With the massive arrival of software-based sequencers and later virtual instruments during the 1990s, the creation of music became finally more affordable, both in costs and in knowledge, than it ever was.

:: Synthesizers

A sound synthesizer (often abbreviated as synthesizer or synth) is an electronic instrument capable of producing a wide range of sounds. Synthesizers generate electric signals (waveforms) which are processed to be converted in interesting sounds. Synthesizers may either imitate other instruments or generate new sonic timbres. They can be controlled through different input devices, such as keyboards, music sequencers and instrument controllers.

Synthesizers use a number of different technologies or programmed algorithms to generate signals, each with their own strengths and weaknesses. Among the most popular sound synthesis techniques are subtractive synthesis, additive synthesis, wavetable synthesis, frequency modulation synthesis, phase distortion synthesis, physical modelling synthesis and sample-based synthesis. Other sound synthesis methods, rarely used, are subharmonic synthesis and granular synthesis.

Synthesizers are often controlled with a piano-style keyboard, leading such instruments to be referred to simply as keyboards. Several other forms of controller have been devised to resemble fingerboards, guitars (guitar synthesizer), violins, wind instruments (wind controller), drums and percussions (electronic drum), etc... Synthesizers without controllers are often called sound modules, and they can be controlled using MIDI or Coltrol Voltage/Gate methods, where the voltage signal typically controls note pitch and the gate signal controls note on/off.



MIDI stands for Musical Instrument Digital Interface. It is an international standard for communication between musical instruments and computers. But we do not necessarily have to hook any external musical instrument to our computer, since there is a music synthesizer built in the sound card of every computer. In fact, this is key to the way midi (.mid) files work, and why they are so small in size. Midi files actually do not contain any music or sound; they contain only instructions telling a sound card which particular built-in sounds, pitches, durations and sequences to play. Think of .mid files as being sheet music, and sound cards as being bands or orchestras. Some sound cards have better quality built-in sounds than others, so a midi music does not sounds the same on different computers equipped with different sound cards. Also, midi files cannot store any lyrics, so midi music will be always instrumental, though simple vocal sounds are available, in the form of choruses that cannot sing any lyrics, but only unarticulate voices. These may be limitations, but the value to .mid files is their tiny size compared to .wav or mp3 files.

:: WAV and MP3

When sound is recorded, it is represented electronically as waveforms. In order to store this sound on a computer, these waveforms must be converted to a digital format. This is done by sampling the waveforms many times per second. The data from this wave sampling is stored in .wav files. It is easy to figure that more frequent sampling will give a more accurate representation of the waveform. In fact, CD quality sampling is done 44100 times per second. Each one of those samples is 2 bytes (16 bits) in size. For stereo music, the left and right channels must both be sampled. If you do the math (44100 samples x 60 minutes x 2 channels x 2 bytes), you will find that one minute of music, sampled at CD quality will make a .wav file about 10.5 MB in size! With the average song being three or four minutes long, .wav files have a voracious appetite for drive space. Files this large are also difficult to transfer over the internet. If the rate of sampling is lowered, the file size can be reduced at the expense of a lower quality sound (since the lower sample rate misses a greater amount of the variations in the waveform).

The MP3 (MPEG layer 3) codec was developed as a form of compression which will reduce the size of .wav files, with the minimal possible loss of quality. MP3 has become a popular format for reducing the size of audio files. Most of the music available for download on the internet is found in this format or similar ones. The reduction in file size is accomplished partly by compression, elimination of inaudible data and the encoding of duplicate data. MP3 encoding programs analyze the sound and discard data that is above or below the range of the human ear, quiet sounds that are drowned out during loud passages or duplicate data. If data is duplicate in both left and right channels, data from one channel can be discarded in the file and later reconstructed on playback. The result is an audio file that sounds nearly the same as the original, but occupies much less space. MP3 can be encoded at different bit-rates, measured in kilobits per second (kbps). Any sound encoded at 128 or more kbps will generally be of good quality. The same one minute of music that was 10.5 MB in size as a .wav file could be around 2 MB as a .mp3 file. A similar length .mid file might be a miniscule 25k, but as I explained before, in these type of files we are not storing sound, but instructions for controlling MIDI sound generators.

:: Music Sequencers

A music sequencer is a hardware device or a software application that can record, edit or play back music, by handling note and performance information in several forms, typically MIDI or CV/Gate, and possibly audio and automation data for plugins and DAWs (Digital Audio Workstations). There are some types of music sequencers, often categorized by handling data types, as following:

MIDI data --> MIDI sequencers

Control Voltage/Gate data --> Analog sequencers

Automation data --> Plugins and DAWs (software sequencers with software instrument/effect plugins attached to them and sequencers mainly used for audio waveforms)

Audio data --> Audio sequencers (including DAWs, loop-based music software, phrase samplers, groove machines, etc...)

Also music sequencers can be categorized by its construction and supporting mode, as following:

Real-time sequencers: on these sequencers, musical notes played by the musician are recorded in real time, as on an audio recorder, and played back with designated pitch, tempo and quantization. For real-time editing, punch in/out features are often supported; however, to edit details, another editing mode may be needed. Built-in sequencers on electronic keyboards often support real-time mode.

Analog sequencers: these sequencers generate sound by using analog electronics. They are designed for both composition and live performance. The user may change the notes in a sequence without entering record mode. Steps (the time interval between each note) are independently adjustable.

Step sequencer: on these sequencers, musical notes are divided into steps, and each step is recorded without exact timing. Instead, the timing of each step is designated separately, either by the order in which the steps are programmed (on bass machines), or by the selection of column buttons (on drum machines). Analog bass machines and drum machines often utilize this mode, along with semi-real-time mode.

Software sequencer: these sequencers are software applications that provide the functionality of a hardware sequencer on a computer. A software sequencer may simulate an analog sequencer. The user may control the software sequencer by using either a graphical user interface or a specialized input device, such as a MIDI controller.

With the advent of MIDI technology, programmers were able to write software that could record and play back the notes played by a musician. Unlike the early sequencers used to play mechanical sounding sequences with exactly equal length, the new ones recorded and played back expressive performances by real musicians. These were typically used to control external synthesizers, especially rack-mounted sound modules, as it was no longer necessary for each synthesizer to have its own keyboard. As the technology matured, sequencers gained more features, and integrated the ability to record multi-track audio.

Many modern sequencers can also control virtual instruments implemented as software plugins, allowing musicians to replace separate synthesizers with software equivalents. Today the term sequencer is often used to describe software sequencers. However, hardware sequencers still exist. Workstation keyboards have their own proprietary built-in MIDI sequencers. Drum machines and some older synthesizers have their own step sequencer built in. There are still also standalone hardware MIDI sequencers, although the market demand for those has diminished greatly due to the greater feature set of their software counterparts.

The images below show Quartz Audio Master, a classic sequencer that can sequence both midi notes (piano roll) and waveform clips (audio multi-track).

Music Sequencer

Music Sequencer

:: VST Technology

VST (Virtual Studio Technology) is an interface for integrating software-based plugins into modern software-based sequencers, audio editors or virtual music studios in general that support this feature. These plugins can emulate sound processors (effects) or sound generators (synthesizers). VST generators are called VSTi (VST instruments). VST and similar technologies use digital signal processing to simulate with software the traditional recording studio hardware. Thousands of plugins exist, both commercial and freeware, and VST is supported by a large number of audio applications. VST plugins are generally run within a Digital Audio Workstation, providing the host application with additional functionality. VST plugins generally provide a custom GUI, displaying controls similar to the physical switches and knobs on audio hardware. Some (often older) plugins rely on the host application for their GUI. Some VST instruments are software emulations of well known hardware synthesizers or audio processors, emulating the look and sonic characteristics of the original equipment. This enables VSTi users to use virtual versions of devices that may be otherwise difficult to obtain.

VST instruments require notes to be sent via MIDI in order to output audio, while effect plugins process audio data (some effect plugins do require a MIDI input too, for example, they might use MIDI sync to modulate the effect in synchronization with the tempo). MIDI messages can often also be used to control parameters of both instrument and effect plugins. Most host applications allow the audio output from one VST to be routed to the audio input of another VST (chaining). For example, output of a VST synthesizer can be sent to a VST reverb effect for further processing.

VST Synthesizer

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