An overview of analog and digital synthesizer design, its components and how they work.
This article list the essentials in subtractive Synthesizer design and programming.
Programming synthesizers require basic knowledge of the different modules in a synthesizer.
This article explains the most important modules with programming tips.
What is Subtractive Synthesis?
Subtractive synthesis is a synthesis method where oscillators generates waveforms and then filter out frequencies over time to make the sound interesting and evolving.
An oscillator is the waveform generator in almost all analog synthesizer designs. It has a limited number of waveforms and on some synthesizers like the famous Prophet 5 they can be combined.
The simple waveforms:
A synthesizer can have 1 to many oscillators per voice but 2 or 3 is typical on an analog synth.
In synths the oscillator abbreviation is:
- VCO for Voltage Controlled Oscillator
- DCO for Digitally Controlled Oscillator
Arturia Pigments analog oscillators
The VCO section on a Roland Jupiter 8 Synth
Cross modulation is a design where one oscilator can modulate an other one. This is effective for generating overtones and sounds outside the fundamental frequency.
Cross Modulation on a Jupiter 8
Roland Jupiter 8 has Cross Modulation where VCO 1 can be modulated by VCO 2 for interesting sounds.
An envelope is a timebased controller used a lot in synthesizers.
ADSR is a typical envelope design containing 4 points. Attack, Decay, Sustain and Release. Some synthesizer has a Hold stage too.
Envelopes are typically used in the filter and amplifier to modify sound over time based on keyboard events (Note on)
A modern Pigments Envelope
Mordern software synthesizers has more control over the envelops than older analog synthesizer had. Arturia Pigments has curves on attack an decay for non linear control.
The filter is an important part of any Subtractive Synthesis design.
The filter is typically controlled by an ADSR envelope with an amount that contols its impact on the sound.
In synth the abbreviation is:
- VCF for Voltage Controlled Filter
- DCF for Digitally Controlled Filter
Arturia Pigments Filters
Amplifier or in short amp is the gain stage in a synthesizer. Amp controlls the volume and amp velocity.
Low Frequency Oscillator or LFO is essentially the same as the sound generating oscillator but it has a much lower frequency.
It is typically used as a controller for modulating parameters to make a sound change over time.
Arturia Pigments LFOs
LFO is often used to pitch- or filter modulate the sound. Tremolo, Vibrato and Autopan is essentially done with an LFO.
A Wavetable is like digital oscillator that generates complex waveforms instead of the simple waveform Oscillators.
It is actually a list of samples (called a table) that can be morphed over time.
Some wavetable based synthesizers:
- Access Virus TI
- Waldorf Quantum
- Waldorf Blofeld
- Steinberg Halion
- Arturia Pigments
- NI Massive/Massive X
- Xfer Serum
Modulation is a way to make the sound interesting over time.
Modulation uses a source to modulate a paramter in the synthesizer.
Some modulation sources:
- After touch
- Mod Wheel
- Modulation Macros
- MIDI continuous controls (CC)
A modulation source can modulate another source for complex modulation.
For example 2 LFOs modulation each other.
Programming synthesizers is a lot easier when you know the basic modules of a generic synthesizer. There might differences in your synths but still they have the same over all components.
It is usually not that hard to program a new synth if you already know and program your own presets on a few synths.
Basic preset programming steps:
- Set the Oscillators
- Set the Envelopes
- Set the Filters
- Set the LFOs
- Modulate Oscillators and Filters with the Envelopes and/or LFOs
It takes a lot of practice to program a specific sound from the top of you head or from listening to other artists music.