An impulsive acoustic radiation source includes an enclosure disposed about an impulse generator to control the generated acoustic spectrum. In some implementations, the impulse source includes electrically nonconducting materials disposed so as to provide a compact means to complete the electrical circuit. In certain implementations, the impulse source includes a restrictor that mechanically guides a "cavity" produced by the pulsed electrical discharge. In other implementations, multiple impulse sources are disposed within an enclosure having walls or other means to define an enclosure for each specific source. Arrangements of multiple impulse sources connected in series and driven by a single circuit and having a reflector disposed about the impulse source or sources are disclosed. In certain implementations, the impulse source is initiated by a small energy electrical discharge that, in a particularly favored implementation, employs an electrode configuration having an initiator electrode in addition to the main electrodes. Also, an impulse source located adjacent to a pulse power subsystem is disclosed.