Bridge and Saddle: Where the String Ends

A vibrating string needs two hard stops, one at each end. Everything between them vibrates; everything outside them does not. The stop at the body end is the saddle, sitting on the bridge. The stop at the headstock end is the nut. The distance between those two points is the speaking length of the string, and it is what the whole instrument is built around.

On an acoustic, the bridge does two jobs at once. It anchors the strings, and it carries their vibration into the top. The strings have a small brass ring crimped onto one end, called a ball end; they drop into holes in the bridge and are held there by tapered bridge pins. Over the top of the bridge sits the saddle, a thin strip of bone or synthetic material, and every bit of the sound you hear from an acoustic passes through it on its way to the soundboard.

An electric bridge has no soundboard to feed, so it is free to be a piece of adjustable hardware instead. That freedom gets used for two things that matter enormously in practice: string height and intonation.

String height, or action, is how far the strings sit above the frets. Low action is easy to press but buzzes; high action is clean but tiring. Intonation is subtler. Pressing a string down stretches it slightly sharp, and the thicker the string, the worse the effect. If every string were exactly the same length, a guitar tuned perfectly on open strings would play out of tune up the neck. The fix is to set each string's saddle a fraction further back, individually, so the fretted notes land where they should.

The other thing an electric bridge can do is move on purpose. A vibrato system — almost universally called a tremolo or a whammy bar, both of which are technically the wrong word, since tremolo means a change in volume and this changes pitch — lets you slacken or tighten every string at once with a lever.