projectM is an awesome music visualizer. DISTRHO ProM makes it work as an audio plugin (CLAP, LV2, VST2 and VST3).

projectM is an awesome music visualizer. DISTRHO ProM makes it work as an audio plugin (CLAP, LV2, VST2 and VST3).

matrixmixer.lv2 is a matrix mixer 🙂
It is available as a LV2 plugin and as a standalone JACK-application. The JACK application can run headless and be remote controlled via OSC.

LV2 synth plugin to emulate AY-3-8910/YM2149 chip sound.
sourceforge.net/projects/aychipsynth
References:
A fully free and self-contained modular synthesizer based on the popular VCV Rack. Available in AudioUnit/CLAP/LV2/VST2/VST3 plugin formats and as a standalone app for FreeBSD, Linux, macOS, Windows and the Web.

DISTRHO Ildaeil is mini-plugin host working as a plugin, allowing one-to-one plugin format reusage. The idea is to load it as a plugin inside your DAW and then the other “real” plugin inside Ildaeil. This allows, for example, a VST3 host to load LV2 plugins and vice-versa.
The Ildaeil name comes from the korean 일대일, which means “one to one”.
The current formats Ildaeil can work as are:
And it can load the following plugin formats:
With a few extra formats through the “Load from file…” action:
You have the need for professional and state-of-the-art audio plug-ins – but don’t have thousands of bucks to spend on it? Then we believe you will love Calf Studio Gear! Focused on high-quality sound processing and a highly usable interface Calf Studio Gear is designed to give you a professional production environment for your open source operating system. Play your SF2 sample banks, create filthy organs, fatten your sounds with phasers, delays, reverbs and other FX, process your recordings with gates, compressors, deesser and finally master your stuff with multiband dynamics – for free! Calf Studio Gear is available exclusively for LINUX-based operating systems and runs as a stand-alone effect rack connectable through Jack sound server or as plug-ins in every audio host that is able to fire up LV2 compliant devices, e.g. the highly recommended Ardour Audio Workstation
calf-studio-gear.org
github.com/calf-studio-gear
en.wikipedia.org/wiki/Calf_Studio_Gear
DrumGizmo is an open source, multichannel, multilayered, cross-platform drum plugin and stand-alone application. It enables you to compose drums in midi and mix them with a multichannel approach. It is comparable to that of mixing a real drumkit that’s has been recorded with a multi mic setup.
LSP (Linux Studio Plugins) is a collection of open-source plugins currently compatible with LADSPA, LV2 and LinuxVST formats. The basic idea is to fill the lack of good and useful plugins under the GNU/Linux platform.
Advanced GTK+ Sequencer is intended to use for music composition. It features a piano roll, as well a synth, matrix editor, drum machine, soundfont2 player, mixer and an output panel.
It’s designed to be highly configurable, you may add effects to its effect chain, add or remove audio channels/pads.
You may set up a fully functional network of engines, therefore exists a link editor for linking audio lines.
In conjunction with AGS you need a realtime kernel and alsa support. `ags` uses conditional locks to keep several threads in sync that’s why you need at least a preemptible kernel.

This is the community version of Element, a modular AU / LV2 / VST / VST3 audio plugin host. Create powerful effects, racks and instruments by connecting nodes to one another. Integrates with your existing hardware via standard protocols such as MIDI.
Features:
- Runs standalone or as a plugin in your DAW
- Route Audio and MIDI from anywhere to anywhere
- Play virtual instruments and effects live
- Create re-usable instruments and effect graphs
- Preloaded plugin graphs
- External sync w/ MIDI clock
- MIDI controller mapping
- Sub graphing – nest graphs within each other
- Custom keyboard shortcuts
- Placeholder nodes
- Built in virtual keyboard
- Multiple undo/redo
