Matthieu Brucher has released version 1.0.0 of ATKBassPreamp, a free and Open Source stereo delay plug-in, for 64-bit Mac OS X (10.11 minimum) and Windows (32 and 64-bit) in VST2, VST3 and AU plug-in formats.
ATKBassPreamp is a bass preamp plugin, modeling the inverter input stage of a Fender Bassman followed by its tone stack.
Just like a bass preamp, you can dose the amount of distortion, bass, medium and high frequencies. The final stage gives you the option of turning the volume up or down, as well as balance the dry sound with the processed sound.
It is built on top of AudioToolKit and JUCE.