| 摘要 |
<p>A protection device for loudspeakers includes circuitry (16) for continuously measuring the average power of an audio signal delivered to a loudspeaker driver and detecting peak levels of said signal in both positive and negative directions. The circuitry (16) is adapted to provide a particular output to switching circuitry (T1) to activate a relay (13) when the average power exceeds a predetermined maximum for a predetermined time which would cause excessive heating in said driver or when said peak levels in either direction exceed predetermined limits set to correspond to the maximum positive or negative excursion limits of said driver. Activation of the relay causes switching of the audio signal path to the driver into an open circuit condition or switches a resistive load into the path to substantially reduce the power to the driver until overload ceases. Separate said circuitry is provided for each driver in a multi-driver speaker arrangement thus providing protection against distortion components in said audio signal caused by clipping. Optional circuitry (B4, R2, C2, 28, T2) for DC protection is also described as is an arrangement wherein the predetermined levels are user adjustable for incorporation into an audio amplifier. </p> |
