This Simple Speaker Protector circuit is then connected the speakers to the amplifier output power of only a few seconds after the amplifier is on, so the speakers do not accept a high voltage appeared and did not hear a rumbling sound from the speakers when the amplifier is on. This material is harmful to the speakers.
When the amplifier is on the bridge D1 is also fed through the amplifier power switch. Capacitor C1 filters the output of the bridge rectifier D1. When the power switch is performed on the transistor Q1 turns on only after the capacitor C2 is sufficiently charged (0.7 V) through resistor R1. Here the value of C2 and R1 are selected so that the delay is about 2 seconds.
As the relay is activated only after a few seconds, the amplifier is on and until then the speaker will remain isolated from the audio output of the amplifier and the speaker is connected to the amplifier output through contact N / O relay. During this initial delay of the amplifier output resistance is based on R2 through contact N / C relay. This is done to ensure that the DC blocking capacitor in the amplifier output is loaded before you connect the speaker
