There seem to be three types of saxophone ligature; each has its own way of applying pressure on the reed and, as a result, affecting the sound produced by the combination of mouthpiece, reed and ligature. The ligature that comes with most instruments is what I call the double-screw metal wrap around type which is usually meant to be used with the screws on the underside of the mouthpiece. These are made by many companies, including Selmer and Yamaha and several reed makers. These hold the reed against the mouthpiece by applying pressure on the reed in parallel to the grain of the reed. If you invert these ligatures, the metal band applies pressure across the grain (there are metal ligatures that are meant to be inverted and have either one or two screws on the upper side of the mouthpiece). Variations include the Harrison or “H” ligature (now made by Rico), whose metal band applies pressure at four points along the reed (the screws are on the underside of the mouthpiece), and the Selmer single screw ligature, whose metal bands apply pressure across the grain (and the screw is on the upper side). Other ligature designs, such as the Rovner, use a special fabric or leather to hold down the reed. The Rovner ligature can be applied with the fabric across the reed and the screw on the upper side of the mouthpiece, or with its metal studs along the reed’s grain with the screw on the underside. A third design uses a pressure plate held in place by a vertical screw – some of these have thin bands that wrap around the mouthpiece to hold the plate against the reed, others have the plate built into a metal mouthpiece. My experience is that the metal ligatures tend to provide a brighter sound (the ligature contributes some vibrations of its own) while the fabric or leather ones result in a more subdued sound (since they contribute little or no vibration). I also feel that a metal ligature used with the screws on the underside of the mouthpiece produces a harder sound, perhaps because of the parallel pressure on the reed, while an inverted ligature produces a slightly softer, cooler sound perhaps because of the cross-grain pressure it applies. The pressure plate designs, and the Harrison, provide a compromise. My personal preference is the Selmer single-screw inverted metal ligature.
