For bands that include a front ensemble (also known as the pit or auxiliary percussion), stationary instrumentation may include orchestral percussion such as timpani, tambourines, maracas, cowbells, congas, wood blocks, marimbas, xylophones, bongos, vibraphones, timbales, claves, guiros, and chimes or tubular bells, concert bass drums, and gongs, as well as a multitude of auxiliary percussion equipment, all depending on the instrumentation of the field show. Drum sets, purpose-built drum racks, and other mounted instruments are also placed here. Until the advent of the pit in the early 1980s, many of these instruments were carried on the field by marching percussionists by hand or on mounting brackets. Some bands also include electronic instruments such as synthesizers, electric guitars, and bass guitar, along with the requisite amplification. If double-reed or string instruments are used, they are usually placed here, but even this usage is very rare due to their relative fragility. Unusual percussive instruments are sometimes used, including brake drums, empty propane tanks, trashcans, railroad ties, stomping rigs, and other interesting sounds. In modern marching band, there is a use of amplification of the front ensemble to help balance out the wind and drumline sections. The use of synthesizers and electronics in the front ensemble can not only help the front ensemble, or "pit", be heard better by the audience and judges, but it can add soundscapes such as voice-overs to help tell the story of a field show, or to add sound effects (for example, a show about nature could have bird/wind/rain sound samples performed by a front ensemble member playing the synthesizer).