1 Tensioning mechanism
2 Snare release lever
4 Tensioning brackets
5 Counter hoop
6 Tensioning screw
The shell of the snare drum is relatively shallow and is generally made either of wood or metal. Plastic is only rarely used.
On the underside of the shell there are grooves for the snares. These are called the snare bed. When the strings are stretched taut they are pressed into these grooves, which improves their contact with the head.
The tensioning mechanism for the snares is on the side of the shell: the percussionist tightens or loosens the strings with a lever, so that they are either pressed against the head or lifted off of it. In addition, the lever is fitted with a screw which allows precise adjustment of the string tension.
The shell always has a small hole for pressure compensation of the enclosed air when the drum is struck.
Extremely shallow versions of the snare drum have become known as piccolo snare drums.
Over both openings of the cylindrical shell a head of calfskin or plastic is stretched. Plastic heads are either clear or coated. The batter head is at the top of the drum, the snare head at the bottom.
The heads are stretched over a flesh hoop, which has a slightly larger diameter than the shell. A counter hoop placed on the flesh hoop is screwed with long screws or threaded rods to the tensioning brackets which are mounted approximately in the middle of the shell.
Rope or cord tensioning, as on the medieval side drum (field drum), is rare today. In order to produce a good tone the heads, which must not be too thick, must have an even tension over-all.
To produce a tone with indefinite pitch the head must meet two criteria:
- Thickness: the thicker the head, the more likely the instrument is to develop a definite pitch. To prevent this, the snare head is somewhat thinner and more elastic than the batter head.
- Tension: it must be possible to tune both heads independently. Most drummers prefer the batter head to be more tightly tensioned.
Until the 20th century musical opinion dictated that a definite pitch was something to be avoided at all costs. Today, however, the tuning of the snare drum to an exact pitch is occasionally required.
The snares, of which there are usually 8–18, are stretched across the snare head and are primarily responsible for the instrument’s crisp sound. What the snares are made of depends on how and where the drum is employed or from where it originated:
In military bands, gut snares are often still preferred for their precise and snappy sound.
In jazz, rock and pop music, wire coil snares create a buzzing and diffuse impression. The snares on orchestral drums are somewhere between these two extremes, being made of silk or nylon wound with metal, although there is currently a tendency to revert to gut snares.
Taut snares containing metal are very susceptible to sympathetic vibration in the orchestra, and can vibrate from the sound of other instruments (such as the horns, or the timpani, which are often close to the snare drum). To prevent this, the drummer immediately releases the snares (hopefully! -:) when the instrument is not being played.
For playing, the snare drum is placed on a firm stand, the height and angle of which can be adjusted.