SlackBuildsOrg/audio/bristol

Bristol is synth emulation package for a diverse range of vintage
synthesisers, electric pianos and organs. The application consists of
a multithreaded audio synthesizer and a user interface called brighton.

jack-audio-connection-kit and liblo are optional (but highly recommended)
dependencies.

Note: If bristol is already installed on the build host, the build will
fail. I assume the bristol authors have a good reason for wanting this
to happen, so I don't alter this behaviour. If you want to try, edit
the SlackBuild and add --disable-version-check to the configure command.
Otherwise, do a "removepkg bristol" before building.