7.2 Synthesizer Concepts
Deluge features subtractive, FM and wavetable synthesis with many customisable options. Some generic synthesis concepts are explained below.
Subtractive Synthesis
Subtractive synthesis operates on the principle of one or more oscillators which generate a tone with harmonic content dependant on the wave shape and type. Harmonic frequencies are then ‘carved out’ using filters to subtract various elements from the signal. This affects the timbre and sound. Additional sound shaping with envelopes, modulation and effects enables more complex sound design.
The basic subtractive concepts are shown in the diagram with many synthesizers expanding these concepts with more complex layering, synchronisation and tuning of oscillators, complex waveforms and noise generators, filters, modulation, effects and more.
FM Synthesis generates sounds which are often described as metallic or bell-like. The generic concepts of FM Synthesis are explained.
FM Synthesis
FM (frequency modulation) synthesis operates on the principle of an oscillator or “operator” generating an initial, basic wave known as the carrier. This then has its frequency rapidly modulated by an additional wave/oscillator known as the modulator. The exact configuration of, at times many carriers and modulators, is called an algorithm. Technically FM synthesis is just very fast vibrato - so fast that the modulation of frequency occurs at a rate which is itself in the “audio range”.
By rapidly modulating the frequency of a wave, whole new repeating wave shapes are created.
Amplitude modulation can be carried out by other modulation devices such as LFO’s. Amplitude modulation can be found in many types of synthesizer.
The third synthesizer type in Deluge is wavetable synthesis.
Wavetable Synthesis
Wavetable synthesizers uses a collection of wave assembled into a package of wavetables. While subtractive synthesis uses a core wave-shape as its audio source, wavetable synthesizers use wavetables as the audio source. The key benefit bing the ability to navigate parts of the wavetable to generate different timbres and sounds. This is essentially the synth oscillator.
Wavetables are navigated to specific wave parts which form the synth oscillator audio source.
The basic wavetable synthesis concepts are shown in the diagram. The core components are the wavetables as a source, typically generated from single cycles, and the ability to navigate the wavetable. Most other features and synth specific and often similar to subtractive synthesis.
Deluge Subtractive Synthesizer Overview
Deluge has a subtractive synthesizer as default, with ring modulation mode option.
Deluge Subtractive Synthesis
Deluge uses two oscillators. High-pass and low-pass filters and 2 LFO and envelope options. In addition the Deluge synth can use sample WAV files as the audio frequency source.
Deluge FM Synthesizer Overview
Deluge has FM synth features and parameters that are configurable.
Deluge FM Synthesis
Deluge uses two carriers and two FM modulators. Regular modulation is also provided by 2 LFO and envelope options.
Deluge Wavetable Synthesizer Overview
Deluge has wavetable synthesizer capability which allows the oscillators TYPE to be set to WAVEtable and where a specific part of the wavetable can be selected as the audio source.
Deluge Wavetable Synthesis
Deluge uses two oscillators plus same functionality also as the default subtractive synths and the audio chain. Wavetables in WAV or AIFF and MONO format can be assigned to one or both of the oscillators. Wave navigation per oscillator is also available in order to change the oscillator wave cycle used as the source. Modulating the wave position is a great way to add variation and movement to a sound.
Deluge supports Mono, WAV and AIF files with a cycle size to the ‘power of two’ starting at 8 upwards. The cycle size of 2048 is the most common. Wavetables can be downloaded freely online from various sources or can be user created directly. These can be stored, and subsequently selected from, the samples library on the SD Card. Many devices such as XFER’s Serum VST plug-in have readily available wavetables that are also compatible with the Deluge wavetable synthesizer. These along with any other specific wavetable files carry meta data tagged ‘clm’ along with the cycle size. Deluge can load any wave file as a wavetable but only the wavetable formatted files will follow the defined and recognised wavetable behaviour and sound.