Only as a reference tone, but I think that was its purpose. I can't imagine that Roland had another other purpose for it. Maybe as a drone. I just turned both of mine on and noted that they beat
Hey, how about taking over the headphone jack? The level could be used to control the pitch of the 'fixed' oscillator and its output could go to the headphone jack rather than to the mixer?
That could be a little fun .. I'll open one of mine up and see what the range is on
the trimmer. Err ... its fixed! it will take more to get it useful.