User:JulesN/foldback
Foldback is the use of rear-facing loudspeakers known as monitor speakers on stage during a live music performance. The sound is amplified with a public address system and directed to the on-stage performers rather than the audience. This sound signal may be produced on the same mixing console as the main mix for the audience (called the 'front of house' mix), or there may be a separate sound engineer and mixing console on stage. Live sound is problematic, and on-stage sound can be the biggest nightmare of all. The famous 'musical difficulties' are often nothing to do with the songs, but simply the result of someone turning up their amplifier too loud on gigs.
The provision of monitor speakers is essential to performers, because without a foldback system, the sound they would hear from front of house would be the reverberated reflections from the rear wall of the venue. The naturally-reflected sound is delayed and distorted. A separate mixed signal is often routed to the foldback speakers, because the performers may also need to hear a mix without electronic effects such as echo and reverb (this is called a "dry mix") to stay in time and in tune with each other. In situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band.
The term "foldback" is sometimes applied to in-ear monitoring systems, also described as artist's cue-mixes, as they are generally set up for individual performers. "Foldback" may less frequently refer to current limiting protection in audio electronic amplifiers.