Sidebar 1: “IT’S NOT THE “PHASE” BUTTON, ITS THE “POL-REV” BUTTON.

Somewhere along the input section of most self-respecting console modules there is a little button, usually with the symbol “Ø” on it, that reverses the polarity of the voltages. Sometimes, the button will be called “Invert,” and once or twice I’ve seen the legend “180°.” Both “Ø” and “180°” refer to phase shift, and these references are misnomers, growing out of sloppy language usage by audio design engineers over the years. Phase shift relates to time delay or offset, and in fact there is no delay involved in the modest little circuit that the “Ø” button engages. Put simply, the circuit reverses the positive and negative voltages of the signal passing through. The reference to phase shift comes from the fact that if you look at an oscilloscope trace of a sine wave whose polarity has been reversed, it appears to have been offset in time by 180°. For years, design engineers have casually described it in such terms. A more accurate term is “pol-rev,” a contraction of “polarity reversal,” and I encourage its usage in better studios, bars and fast-food joints.