The marching bass drum is a key component of the percussion section, which usually also includes snare drums, tenor drums, cymbals and pit percussion (various percussion instruments performed by players who don't march). The marching percussion section forms what is known as the battery, as it provides a lot of the power to a marching band. Marching bands typically have multiple bass drum players, and unlike other marching percussion instruments, each player's bass drum varies in size and pitch.
Marching bass drums differ in size, depending on the number of players available. Marching bands usually have five bass drum players, but this number can vary. While the bass drum is typically a very large drum, marching bass drums can even be very small in size, sometimes just a few inches larger than a snare drum. As each player plays a different-size bass drum, the pitches vary as well, with bigger bass drums producing lower tones than smaller bass drums.
Unlike other percussion instruments in the battery (the occasional exception being the cymbals), each bass drum player typically plays a different part than the other bass drum players. As each bass drum has a different pitch, many combinations can be used to create different sounds and rhythms. One of the most common techniques bass drummers do is called runs, where the bass drum part essentially runs from the highest drum to the lowest drum or vice-versa. Done at a quick speed, this can create a visual and audible effect.
The marching bass drum is the only drum on the field that is played on both sides of the drum. While the snare drum has a batter head (the drum head that is hit) and a resonant head (the drum head on the bottom of the drum), both heads on the bass drum are the same, and both can be played. The bass drum is positioned on the player with the shell of the drum attached to the carrier located on his shoulders, making it possible for his left hand to hit one of the drum heads, while his right hand can hit the other head. The bass drum mallets are typically positioned to hit the center of the head, with the player holding the mallet so it's angled at about 1 o'clock on a clock.
The bass drum section usually marches alongside the battery, which is often near the middle or back of the field. Positioning can vary based on the choreography of the piece, but the bass drums are usually found near the battery near the middle of the field. Bass drum players typically stand sideways, so they are facing one of the end zones of a football field, making their bass drum heads visible to spectators in the stands. The players typically position themselves in order, from the highest bass drum to the lowest bass drum or vice-versa.