The Blackstar with Girth is a total redesign of our high gain overdrive. While still the high gain little brother of the Liquid Sunshine in spirit, the design has been drastically changed for improved dynamics and less noise. Controls are tailored for use with many different guitars and amplifiers.
Most importantly, the Blackstar will retain characteristics of individual guitars and pickups. This has been my main complaint with the higher gain pedals that I have owned. No matter what guitar I plugged in there was very little difference in sound. Dynamics and pick attack will not get lost with this pedal.
So you have your usual overdrive controls, Drive, Tone, Level, but what does that other knob do? The Girth knob makes everything sound bigger. It adds some low end oomph, and a little gain on the top end.