rncbc.org a.k.a. Rui Nuno Capela

The qtractor_0.4.2-1.rncbc.ubuntu804_i386.deb package depends on librubberband1, which is not wildly available out there. For your convenience, I've made it myself available, here:

• librubberband1_1.3.0-1.rncbc.ubuntu804_i386.deb
• librubberband-dev_1.3.0-1.rncbc.ubuntu804_i386.deb
• rubberband_1.3.0-1.rncbc.ubuntu804_i386.deb
• rubberband-ladspa_1.3.0-1.rncbc.ubuntu804_i386.deb

You should only need to install the first one. The others are optional.

Cheers.