I wonder if it's not simply a matter of a stereo spread control as one would get with an stereo to MS to stereo conversion, where in the MS state, one can vary the width of the stereo signal.
If we don't assume that someone tries to spread a mono signal, but has a stereo signal and is simply playing with the focus of that signal for artistic effect, then that may work. It would also explain the knob I remember seeing on some old tube radio, where there was a balance wheel and a plenum knob. Been ages, though, so I wouldn't vouch for remembering this perfectly correctly. So it would be equivalent to what some mixing desks have: a stereo width control, and a left-right control, that would be consistent with what the passage says about controling the movement between the spakers (left right control) and point to plenum (stereo width control). That would be my best guess, unless someone comes up with a better reading. Ronald _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
