Intrinsically safe audio circuit for a portable two-way radio

An audio circuit and loudspeaker arrangement is disclosed for use in an intrinsically safe portable two-way radio device. The arrangement meets the requirements for an intrinsically safe design by dividing the loudspeaker voice coil into separate coils 210, 212 to limit the energy storage in any one of the coils. Each voice coil 210, 212 is separately driven by a respective audio power amplifier 202, 204, each amplifier providing a substantially identical signal. The output of each amplifier is current limited by redundant current limiter circuits 218, 218 and 220, 220. The current limit value may be chosen to avoid thermal ignition. Based on this level of current, the coil inductance may be chosen to comply with stored energy requirements to avoid spark ignition. The required audio volume level is then provided by the use of multiple drive coils. The drive coils may also be physically separated from each other in a manner that meets requirements for dielectric strength.