sine-synth is a primitive synthesizer demo program written in C#. It displays a keyboard and lets you click on keys to play notes. The only sound it makes is sine waves. It plays output through the cross-platform audio library PortAudio, using the PortAudio.Net wrapper library.
Be sure to use git-clone --recursive since this project includes (a slightly modified version of) PortAudio.Net as a git submodule.
$ make
To run, you will need to have the PortAudio shared library installed. On Ubuntu, install the libportaudio2 package.
$ mono synth.exe
C:\sine-synth> dotnet build
To run, you will need a PortAudio binary DLL. You can download binaries for Windows from the portaudio-binaries GitHub project. You want the 64-bit DLL. Rename it from libportaudio64bit.dll to libportaudio.dll and put it either in somewhere your PATH, or in the bin\Debug directory where the sine-synth binaries are generated.
C:\sine-synth> bin\debug\sine-synth