Two 200mm "Redback" woofers (one shown) and a single Motorola KSN-1141A piezoelectric horn are used in the Foldback Speaker. The woofers are protected by steel mesh grilles.

This versatile foldback loudspeaker is suitable for stage musicians, vocalists, entertainers and performers. It uses readily available loudspeaker drivers and can be built using quite basic hand and power tools.

Foldback loudspeakers, commonly called "wedges" because of their shape, are used by musicians so that they can hear themselves over and above the general noise level in a performance venue. Often there are several foldback loudspeakers on stage, for example, one for the keyboard player, one for the vocalists and one or two for guitarists (bass and lead).

Without foldback loudspeakers, the performers would have to rely on the sound projected to the audience via conventional "front of house" loudspeakers. However, they may find it difficult to hear from their location behind the speakers and there can also be a considerable delay before the sound reaches them. This delay will cause the performance to become slow and very deliberate as the performers attempt to sing or play and then wait to listen. With foldback speakers, the performance can be kept tight and lively.

Foldback loudspeakers are designed with quite different criteria compared to conventional types and as a consequence they look and sound different. While conventional loudspeakers project the sound away from the performers and toward the audience, a foldback loudspeaker does the opposite and projects the sound toward the performers themselves; this provides the perfect recipe for acoustic feedback.