Sorcer is a polyphonic wavetable synth LV2 plugin. Its sonic fingerprint is one of harsh modulated sub-bass driven walls of sound. Two morphing wavetable oscillators and one sine oscillator provide the generation routines. The LFO can be mapped to wavetable modulation as well as filter cutoff. An ADSR allows for shaping the resulting sound, while a master volume finishes the signal chain. Easily creating a variety of dubstep basslines and harsh pad sounds.
The source code is available from the Sorcer page on Github but your package manager probably has a pre-compiled version!
Oscillators are the sound generators in most synths - Sorcer is no different. Sorcer has 3 oscillators, two “Wave” oscillators that use wavetables to generate audio, and one “Sub-Bass” sine-wave oscillator.
Wave oscillators allow fading between two timbres by moving the X/Y pad in a horizontal direction. Vertically moving changes the volume of the oscillator. The sub-bass oscillator only has a volume - it always plays a sine-wave, as this is the lowest frequency possible.
Wavetables are short recordings of a single-cycle off sound. This allows the synth to repeatedly play the same cycle of audio, and create a continuous tone which has a specific timbre due to the harmonics in the recorded audio.
Sorcer has four wavetable recordings; and uses two per wavetable oscillator. The recordings are carefully chosen to have similar sound characteristics, that when faded between cause a nice spectral transition.
Aliasing and Artifacts¶
Note that wavetable synthesis generally has some side effects. Playing a sample back at a different rate (altering the speed) creates some artifacts. With playback rates close to unity these artifacts can be audible unless some interpolation is done.
Aliasing can be avoided by interpolation, or careful pre-processing of the recorded waveform. As pitch goes up harmonics can be removed from the signal, which avoids aliasing. In its current state, Sorcer does not do either of interpolation of the waveform or pre-processing of the waveform.
Why not just fix the Aliasing?¶
Although possible to add, it would change the sound of Sorcer - and change any existing songs that have written. For that reason, Sorcer will not see any improvements in its playback engine - but fear not - OpenAV has plans to release new synths in the future with alias-avoidance and more capable modulation than Sorcer ever had!
Envelopes and Modulation¶
Sorcer also has some modulation and enveloping features, an LFO can modulate the filter and wavetables, while the ADSR allows controlling the volume per-note. Lets look at these parts in a little more detail.
- The LFO section has 4 controls:
The speed and amplitude of the LFO itself is controlled by the Speed and Amp dials. The W1 and W2 dials control the amount of the LFO signal that should be used to modulate the Wave1 or Wave2 horizontal position. This is very useful for creating constantly morphing dubstep-bass sounds!
The “remove” section contains a lowpass filter with a cutoff dial, and a modulation dial. The cutoff dial sets a static value to the lowpass filter - useful to muffle the bass sound and leave some space in the mix for other instruments. To add more energy to the mix, turn up the Modulation dial to change the Cutoff by the LFO output.
The ADSR provides the final touches on the sound - the defaults provide a wall of sound, but add a fade in and some decay to build pad-like sounds..
The master section provides a compressor with Gain, Threshold, Attack and Release. A master-volume slider allows taming Sorcer to keep it in its place in the mix.
That was a whirlwind fast tour of the Sorcer synth - although its limited in its scope, it is a good synth to start using for basslines, and understand the way routing inside a synthesizer works. Of course, for a heavy dubstep modulated bassline, Sorcer is the easiest way to get that super heavy sub-bass too!