Occasionally, after installing a new component in your car stereo system, you will notice a 'pop' when you turn the receiver On or Off. This is usually caused during shut-down of the power by components in the system which turn off before the amplifier turns off. In most cases, the component is an EQ, or signal processor. Usually adding a slight turn-off delay to the processor in question can solve this problem. This added delay allows the processor to remain on until the amplifier has powered down, thus preventing the pop.

If you have the 'pop' when the system turns on, it may be due to the amplifier turning on prior to the offending component. Adding a little turn-on delay to the amplifier will usually resolve this. Many components sold today have these delays built in. Check the manual to see if this is an adjustable feature on your component if you have this problem.

If your processor does not offer this feature, you can build your own delay circuit with a 1N4004 diode and a capacitor. Add a diode in series with the processor's turn-on lead, striped side of the diode towards the EQ. Then add a capacitor in parallel, the positive side of the capacitor connected to the striped side of the diode, the negative side of the capacitor going to the vehicle's chassis ground (NOT to the body of the radio or processor chassis). Experimenting with the capacitor value will give you the right amount of delay before the EQ shuts off. You don't want it to be very long, just long enough to make sure the amp is off before the EQ powers down. The capacitor value of 220-1000 uF is about right, and make sure the capacitor is a polarized electrolytic, 16V or higher. The diode alone will introduce a 0.7V drop on the remote wire, but this usually does not effect most processors enough to cause them to shut down earlier than the rest of the system.