Analog Warmth or Digital Precision: Oscillators create the Sound
What is an Oscillator?
In music production, an oscillator refers to an electronic device or circuit that produces a recurring electrical signal, convertible into audible sound. Oscillators are the foundational component of synthesizers, enabling the creation of a diverse array of sounds, ranging from simple sine waves to intricate and dynamic textures.
The three main parameters of an oscillator are:
Frequency: The frequency of an oscillator represents how frequently the waveform repeats within one second. Frequency is measured in Hertz (Hz), and it is perceived as pitch. A faster repeating waveform will result in a higher pitch, while a slower waveform will result in a lower pitch.
Amplitude: The amplitude of an oscillator signifies the intensity of the electrical signal it generates. Basically, the volume. Measured in decibels (dB), amplitude correlates with the perceived loudness of the sound. A higher amplitude yields a louder sound, while a lower amplitude produces a quieter sound.
Waveshape: The waveshape of an oscillator is the shape of the electrical signal. The waveshape of an oscillator determines the timbre or tone color of the sound. There are many different types of waveshapes, but the four most common are sine, square, triangle, and sawtooth.
Oscillators are an essential part of any synthesizer, and they are used by musicians and sound designers to create a wide variety of sounds.
Sine Wave
The sine wave is the simplest and purest waveform, containing only a single harmonic. It has a smooth rounded shape that traces a sine curve over time.
Sine waves sound very soft and clear, like a whistle or flute. They are excellent for making bass sounds due to containing only the fundamental tone without any higher harmonics.
Square Wave
Square waves abruptly switch back and forth between a positive and negative value, creating a jagged waveform resembling a square. The sudden jumps between high and low values introduce more harmonics, making square waves sound hollow, woody and retro.
Square waves work well for basses, leads, and synth brass sounds due to their warm harmonic character. At higher pitches, they also emulate chime or bell-like tones.
Saw Wave
The sawtooth wave ramps smoothly up to the peak before instantly dropping back down to the bottom, repeating to create its recognizable jagged saw-like shape. Saw waves are the richest in harmonics besides noise waves and produce a bright, buzzy tone.
Sawtooth waves can be used across the entire synthesizer's range. They are commonly used for synth leads, pads and strings due their versatility in producing analog synthesizer tones.
Triangle Wave
The triangle wave traces smooth, even slopes between peaks and valleys to generate its recognizable triangular shape. Triangle waves contain only odd-number harmonics, giving them a hollow, woody character.
Triangle waves have a warmer, rounder sound compared to square waves due to the lack of even-numbered harmonics. They can be used for softer leads and rich basses that need extra warmth and clarity.
Noise & Custom Waves
In addition to the standard geometric waveforms, software synthesizers can also generate noise or random waveforms, as well as allow loading of custom audio files to use as oscillator sources.
White noise produces a random assortment of all frequencies equally. Filtering white noise generates colored noise, allowing tone shaping for sound effects, percussion or cymbal sounds, wind or ocean ambiances and more. Any audio file loaded through a sampler can also be used as an oscillator for extreme creativity and customization.
Analog vs Digital Oscillators
Analog synthesizers generate their waveforms using dedicated circuitry such as voltage controlled oscillators (VCOs) made from capacitors, resistors and transistors wired together. This all analog circuitry imparts richer, warmer and more unstable characteristics compared to strictly digital methods.
Software synthesizers on the other hand generate waveforms using mathematical calculations and digital signal processing (DSP). This means they are perfectly accurate and stable, staying locked to their tuning without drifting. However, they may risk sounding sterile without additional sonic coloring and behaviors added deliberately during sound design.
Many software synthesizers model analog-style drift, instability and character using various programming tricks to capture a classic analog vibe. Some advantages software oscillators have is the ability to quickly switch waveforms, sync multiple oscillators together and achieve unlimited polyphony at little CPU expense thanks to their digital nature.
Modulation
Oscillators can be modulated by envelopes, LFOs (low frequency oscillators) or external control sources to dynamically manipulate the waveform over time rather than remaining static. Common parameters to modulate include:
Pitch: Adding vibrato, chords, arpeggios or harmonic themes
Volume: Adding tremolo or amplitude modulation
Pulse Width: For square waves only, altering duty cycle width changes timbre
Phase: Shifting the start point of an oscillator subtly animates the sound
Frequency: Sweeping across the frequency range creates dramatic effects
By adding modulation, oscillators transform into living, dynamic sources rather than plain repetitive waveforms. Extensive modulation capabilities set software synthesizers apart in creative potential compared to analog hardware.
In Summary
Oscillators form the foundation of subtractive synthesis, generating raw waveforms that get sculpted into musical sounds. The type of waveform combined with modulation and processing greatly influences the character and tone ultimately achieved.
Understanding oscillator fundamentals is essential for mastering software synthesizers. Experimenting with combining multiple waveforms at related harmonic ratios or dissonant intervals generates new textures. Modulating frequency, pulse width, volume and phase keeps sounds evolving organically over time.
From deep booming basses to screaming leads to mellow pads and ambient dreamscapes, the versatile oscillator serves as the pivotal starting point for all the synthesized magic software synthesizers make possible today and the endless sonic exploration they invite.