SYNTHESIZERS

What is a synthesiser

An electronic sound generator capable of creating and manipulating synthetic sounds.

Now more common to use synths as DAW plug-ins, but the warmth and authenticity of vintage analogue equipment are highly regarded

Parts of a synthesizer

• Oscillator

• Filter

• Envelope

• LFO

• Amplifier

Oscillator

• Generates an initial sound at pitch, and allows you to choose a wave shape.

• Each wave shape has different harmonic content and thus can be used to create different timbres.

Oscillator - Sine Wave

• Pure tone

• Basic building block of sound

Oscillator - Triangle Wave

• Slightly harsher than sine wave

• Flute-like sounds and pads

Oscillator - Sawtooth Wave

• Even and edgy sound

• Strings, basses, pads and brass/dance leads

Oscillator - Square Wave

• Hollow and woody

• Clarinets, oboes and bass sounds

Oscillator - Pulse Wave

• Nasal sounding

• Variable pulse width / mark-space ratio

• Reed instruments and basses

Oscillator - Noise

• Noise generator creates a random signal. White noise consists of all frequencies at an equal amplitude

• Other colours of noise have different frequency distributions

• Can be used to simulate wind or percussive sounds like cymbals

• Can be filtered to create a sweeping effect

Oscillator Controls

• First select an octave

• Two further tuning controls are:

  • Coarse tuning (sets pitch in semitones)

  • Fine-tuning is measured in cents (100 cents to semitone) - Can be used to create a chorus effect

• Most synths have more than one oscillator

Synthesiser - Polyphony

States how many notes a synth can play at once.

A monophonic synth can only play one note at a time

Synthesiser - Portamento (Glide)

Used to alter the amount of time it takes to slide between two overlapping notes

Synthesiser - Pitch bend

A synth’s pitch bend range can be altered - How many semitones the pitch bend wheel or MIDI data will bend a note up or down by

Filter

• Removes frequencies from the initial signal to shape the sound

• A Low Pass Filter is often incorporated.

• Cutoff frequency is the point at which the filter begins to remove frequencies

• Some synths also include HPFs or Band pass filters

Filter - Resonance

• Often used on a synth filter to add a characteristic narrow boost of frequencies around the cutoff

• Accents a small range of frequencies and creates a ‘whistly’ sound that makes the signal close to the cutoff seem brighter and harsher

• High resonance settings lead to self-oscillation, where the most of a specific frequency is so loud, the filter ‘creates’ a pitched note

Envelope

• Used to control the oscillator, filter and/or amplifier, depending on the specific synth.

Four envelope stages are:

1. Attack

2. Decay

3. Sustain

4. Release

-Parameters controlled by an envelope include pitch, filter cutoff frequency and volume.

-The envelope plays a part in creating a sounds timbre, along with a signal’s harmonic content. It is part of what helps us to tell a piano apart from a violin.

Envelope - Attack

The time taken for the parameter to increase from 0 to the maximum level

Envelope - Decay

The time taken for the parameter to decrease to the sustain level

Envelope - Sustain

The level at which the parameter is held whilst the key remains pressed

Envelope - Release

The time taken for the parameter to decrease to 0, once the key is released.

Amplifier

• Controls the sound’s volume

• Control signals such as envelopes and LFOs can be used to alter the volume over time

LFO

• Low Frequency Oscillator is a control signal used to alter a parameter over time (like an envelope)

• Most synths can use LFOs to control different modules, if controlling the oscillator, it can change the base pitch generated creating vibrato

• If modulating the filter cutoff frequency, it will periodically change this according to LFO wave shape

LFOs can be synced to tempo of a project in a DAW which creates effects that are in time with the whole track

LFO - Settings

• Rate

• Depth

• Shape

LFO - Settings - Rate

Speed at which the modulation takes place.

Can either be synced to a note value in a DAW or given an absolute value in Hertz (often between 0.05Hz and 15Hz)

LFO - Settings - Depth

How much the modulation affects the assigned element of the synth.

The greater the depth, the wider the range of values for the modulated parameter.

LFO - Settings - Shape

Type of waveform used to modulate the signal e.g. sawtooth, sine or square

Historically important synths

• Moog Modular (1965) - Switched on Bach

• Minimoog (1969) - Are ‘Friends’ Electric?

• Sequential Circuits Prophet-5 (1977) - Take on me (Opening riff)

• Roland Jupiter-8 (JP-8) (1981) - Radio Ga Ga

• Roland TB-303 (1982) - Everybody needs a 303

• Yamaha DX-7 (1983) - The motions of Stars

• Korg M1 (1988) - You Gotta Be

Types of synthesis

• Subtractive

• Additive

• FM (Frequency Modulation)

• PM (Physical Modelling)

• Granular

Subtractive Synthesis

Additive Synthesis

FM (Frequency Modulation) Synthesis

PM (Physical Modelling) Synthesis

Granular synthesis

Benefits of Software Synthesisers

• Can be automated, MIDI controlled and easily sequenced

• Daws with a global tempo allow you to easily sync LFOs/Arpeggiators to a note value (much harder on hardware synth)

• Stay in tune reliably (common for analogue to detune when they heat up)

• Better Signal-to-noise ration

• Wide variety of presets available at touch of a button

• Can create own presets and share on internet

• Can use multiple instances of plug-in

• Can have more envelope stages, types of waveform, oscillators and filter types.

Benefits of Hardware Synthesisers

• Enthusiasts refer to the analogue sound as ‘warm’ when compared to harsher or ‘sterile’ digital sound. This is because of flaws associated with analogue tech - like tuning drifting, noise, aurally pleasing distortion and subtle random variations in wave shape, amplitude and frequency

• Possible to use CV/gate systems to sync analogue equipment together. Converters list to connect analogue synths to MIDI equipment

• Music can stand out from the crowd - Less reliant on presets and sounds others are using - Sounds more individual

• Have a ‘hands-on’ interface - with permanently routed controls. Easy to change settings on the fly