In Praise of The Tractrix

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The tractrix. What the hell is it? Simplest answer is that it's a mathematical curve that can be produced mechanically by the rotation of a rod or a line through a plane: in itself not a fact that immediately strikes one as interesting, methinks. But as it turns out, it has a very practical application that might not be obvious to a non sound engineer; and something that has impacted on the lives of just about everyone who loves music. The tractrix curve is one of two such curves, the other being the exponential curve, employed in the design of loudspeakers for the last century or so, either in the domestic realm, or, more particularly in the sphere of the auditorium or stadium PA system. In short, it's the basis of the horn-loaded loudspeaker/loudspeaker cabinet that makes projecting music to its audience as loudly and efficiently as possible. The horn loudspeaker is the most effective projector of sound for the least energy input we have to date. I have written quite a bit in the past about sound systems and loudspeakers in particular, and I will return to the specifics of the horn-loaded system in due course. But not tonight, as I want to finish my wine and retire to bed: more later...

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