how to get rid of turn on thump??

I just in stalled two Kicker 12"s in a 1999 Jeep Cheereke.  They sound great but there is a huge turn on thump when you turn it on and off.  If it helps any this amp is intergrated with the stock stereo through a line out con verter. I have installed a ground loop isolator and it didnt help any.  The rcas are run down the passanger side and the 12 volt is run down the driver side.  Any help with this matter would be great!  Thanks in advance.  Brian

Our friend at Velocity Motors writes:

This kind of problem is often caused by transients in the signal processor as it powers down finding their way into the signal path, which the amplifier then transmits to the speakers.

Usually this can be solved by adding a little turn-off delay to the processor. This allows the processor to stay powered on for a short time after the amplifiers have powered down, thus preventing the pop.

Many components sold today (such as crossovers, equalizers, etc) have delays built-in. Read your manual to see if it is possible to set this delay on your piece of equipment or be sure to look for this feature during your next car audio purchase.

If your processor does not have this feature, you can build your own delay circuit with a diode and a capacitor. Add a 1N4004 diode in series with the processor's turn-on lead, striped side towards the EQ. Then add a capacitor in parallel, the (+) side of the cap connects to the striped (processor) side of the diode, the (-) side of the cap goes to ground (not the radio or EQ chassis - connect to the car chassis).

Experimenting with the cap value will give you the right amount of delay before the EQ shuts off. You don't want it too long, just long enough to make sure the amp is off before the EQ powers down. 220 - 1000 uF is about right, and make sure the cap is a polarized electrolytic, 16V or higher. Also keep in mind that the diode will introduce a 0.7V drop on the remote wire, which can cause the processor to power down before the rest of the system.

With the fans, I would wire then along with the remote turn on lead of the system so there is continuous cooling for the amplifiers.

Jeff

Installer/Owner http://www.velocitymotorsport.com All information is for reference only. It's up to the installer to test all target wires and use a DMM when ever possible

02 Odyssey / 99 F4

Thanks for the info.  I connected the remote turn on wire to the 12 volt switched wire on the factory radio.  Will this be o.k with this circuit?  Also , the anode side of the diode should face the radio correct? The cap should tie into the downstream side of the diode(- side) right?  Sorry for all of the questions.  Brian