Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Some of the first powered loudspeakers were JBL monitor speakers. This involves the use of audio equipment such as microphones, recording devices, and loudspeakers. Such units are best suited to outputs designed for headphones or loudspeakers. Sound is delivered through an amplifier and two or more integrated loudspeakers. Binaural recordings are made specifically to be heard through headphones rather than loudspeakers. JBL is an American company that manufactures audio equipment, including loudspeakers and headphones. The first practical loudspeakers, introduced around the turn of the 20th century, were horn speakers. Each of these enclosures carried four JBL D140 loudspeakers. Soon I bought a microphone, then loudspeakers, then an echo, then a synthesizer. This is achieved by using multiple discrete audio channels routed to an array of loudspeakers. They can also provide a level of sound fidelity greater than loudspeakers of similar cost. The rumble filter prevents this noise from being amplified and sent to the loudspeakers. The sound was diffused throughout the cinema, controlled by an engineer using some 54 loudspeakers. They operate similarly to Planar Magnetic Loudspeakers.