All acoustic percussion instruments are allowed for drum corps competitions.
The battery is the group of percussion instruments that march or otherwise move on the field. Typically, a drum corps uses three types of drums in the battery, with the possibility of the addition of crash cymbals.
The marching snare is the highest pitched percussion instrument in the battery. The batter (top) head of the drum is tuned in such a way that its sound can easily cut through the rest of the battery. This sound is generally very different from a "wet" concert snare sound. A harness (or sling) is worn to free the hands for playing while marching.
The marching tenor drums are a combination of three, four, five, or six drums connected on the harness. Each of the drums is tuned to a different pitch. These are often referred to as "tri-toms", "quads", "quints", and "six-packs".
The lowest pitch instrument in the battery is the set of bass drums. Usually, each individual in the bass drum section will wear his or her own drum, pitched differently than all others. With four, five or six differently pitched bass drums, complicated rhythms are split between as many individuals.
In some corps there are marching crash cymbal (plate) players. Many corps, in order to use the maximum 135 members more efficiently, use musicians from the pit to supply the cymbal sounds. For those corps who march a cymbal line, the unison and split parts can create effect musically as well as visually.
The Front Ensemble (also referred to as the "pit", due to its resemblance of the pit orchestra percussion section) was non-existent in the early stages of drum and bugle corps. Corps members playing timpani and keyboards marched on the field. Developments in the activity led to the grounding of certain percussion instruments and thus, the formation of the pit.
The basis of the modern Front Ensemble is the keyboard. There are a variety of keyboard instruments available for corps to use, including the marimba, xylohpone, vibraphone, and orchestra bells. DCI recently passed a rules change (proposed by George Hopkins) that allowed for the use of electronics and amplification.
The tympani is used to accent the melody and bring out the bass line.
Other Percussion Instruments
There is a practically unlimited variety of additional percussion instruments that can be used in the pit to add color and timbre to the rhythm. Some are melodic, such as chimes and crotales. Some are semi-melodic, such as temple blocks, cowbells, and congas. Multicultural percussion instruments are often used to match the style of the music. Many drum corps do not march field cymbals because they believe they can achieve the same effectiveness through use of cymbals in the Front Ensemble.