synthv1 is an old-school all-digital 4-oscillator subtractive polyphonic synthesizer with stereo fx.
Features:
- a pure stand-alone JACK client with JACK-session, NSM (Non Session management) and both JACK MIDI and ALSA MIDI input support;
- a LV2 instrument plug-in. (URI: synthv1.sourceforge.net/lv2)
Cecilia is an audio signal processing environment aimed at sound designers. Cecilia mangles sound in ways unheard of. Cecilia lets you create your own GUI using a simple syntax. Cecilia comes with many original built-in modules and presets for sound effects and synthesis.
ajaxsoundstudio.com/software/cecilia
Frinika is a free, complete music workstation software for Linux, Windows, Mac OSX and other operating systems running Java. It features a sequencer, soft-synths, real-time effects and audio recording.
ZynAddSubFX is a fully featured open source software synthesizer capable of making a countless number of instruments …
zynaddsubfx.sourceforge.net
zynaddsubfx.sourceforge.net/download
VST version
en.wikipedia.org/wiki/ZynAddSubFX
Produce music with your computer by creating melodies and beats, synthesizing and mixing sounds, arranging samples and much more. Playback instruments, samples and plugins with a typing or MIDI keyboard in a user-friendly and modern interface. Bundled with ready-to-use content from an assortment of instrument and effect plugins, presets and samples to VST and SoundFont support.
lmms.io
github.com/LMMS
en.wikipedia.org/wiki/LMMS
The Audio File 