Abstract: A compact horn speaker suitable for use on emergency vehicles has a rear-facing motor circuit, a horn plate, and a mouth section. The horn plate has a plurality of horns folded therein in a plane perpendicular to the longitudinal direction of the speaker. The phase plug for the motor circuit is integrally formed on the horn plate and has a plurality of apertures each opening to a folded horn in the horn plate. The folded horns are connected to a horn mouth formed in the mouth section. The mouth section is formed of a thermally conductive material and has an integrally formed receptacle for receiving the magnet assembly of the motor circuit. The receptacle holds the motor circuit firmly in position and provides efficient thermal dissipation via the horn structure for heat generated by the motor circuit during operation.