Abstract: A circuit for protecting speakers connected to the output of an audio amplifier. The output of the amplifier is connected to a filter which blocks normal audio frequency signals but passes both high and low frequency signals outside the normal audio range. The positive and negative filter output signals are connected respectively to the inverting and non-inverting inputs of an operational amplifier whose output is connected via a turn-on delay circuit to a speaker relay, which, when closed, connects the speaker to the amplifier. The turn-on delay circuit prevents speaker relay closure until turn-on transients have ended. If a DC voltage or a high frequency signal is present at the amplifier output, the operational amplifier generates a signal to open the relay thereby disconnecting the speaker from the amplifier output. The speaker relay quickly opens when power is turned off so that amplifier turn-off transients are not connected to the speaker either.