Last Updated on July 11, 2021
helm is an open source MIDI enabled polyphonic music synthesizer with an easy to use parameter modulation system with real-time graphical feedback.
helm can run as a standalone synthesizer or as an LV2, VST, VST3, AU or AAX plugin.
helm has a subtractive synthesizer engine with three oscillators with 15 anti-aliased waveforms, cross modulation, 32 voice polyphony, a low-pass, high-pass, band-pass, notch, low-shelf, high-shelf and all-pass filter. There is also a formant filter, stutter, delay and reverb effects, patch browsing, MIDI learn and more.
Features include:
- Modules:
- Oscillators with waveform selector, cross modulation, tune/transpose, and unison.
- Sub with waveform selector, shuffle, octave down.
- Mixer – controls the gain of each oscillator sound score and a white noise source.
- Feedback a very quick delay line/comb filter inserted into each voice.
- Filter – boosts or reduces different frequencies in each playing voice. Each type of filter has different characteristics: Filter response, Filter type, Filter blend, Filter drive, Envelope depth, and Key track.
- Stutter – samples a section of input audio and repeats it.
- Formant – a type of filter that sounds like a person’s mouth. Create different vowel sounds by picking different spots in the X/Y pad.
- Distortion – set the style of the distortion with soft clip, hard clip, linear fold, and sine fold.
- Delay – essentially an “echo” effect”. It takes the input audio and repeats it while reducing the gain of each consecutive repeat.
- Reverb – simulates audio reflections of a room or space by having many delay lines overlaid upon each other.
- Modulation – change an audio or performance control over time to make dynamic/morphing patches.
- envelopes in Helm are ADSR (attack→decay→sustain→release) envelopes. They are polyphonic (one instance per voice) and are useful for bringing in and fading out a value like the amplitude or filter cutoff of a voice.
- LFO – low frequency oscillator
- Step Sequencer – a modulation source that cycles through a series of steps.
- Graphical keyboard – with aftertouch, note, velocity, mod wheel, pitch wheel, and random mods.
- OpenGL interface.
- 32-bit and 64-bit versions.
- Cross platform support – runs under Linux, Mac OS X, and Windows operating systems.
Website: tytel.org/helm
Support: Manual, FAQ, GitHub code repository
Developer: Matt Tytel
License: GNU General Public License v3.0
helm is written in C++. Learn C++ with our recommended free books and free tutorials.
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