Sub fades when driving but comes back on when slowing down?

Question

Hey everyone,

I have a alpine Type-R sub with 500 rms powered by an alpine amp 500 rms in my honda civic. Its worked fine for a few months but now recently when I drive it fades out but when I slow down and let off the gas it comes back on? Any ideas whats wrong? Do I need a capicitor or is it faulty wires?

Answer 1

If you have the car sitting still, and rev the engine, does the sub cut out and come back when you idle?

There's a few possibilities.

First, you may have a loose connection somewhere that's losing contact when your vehicle accelerates.  Check the connections at the battery terminals, fuse holder, amplifier terminals, and ground point.  The loose connection may be at the fuse holder itself; make sure the fuse fits snugly in the holder.

Second, you may have a problem with your vehicle's voltage regulator, causing your alternator to produce too high of a voltage.  Many amplifiers have protective circuits that will shut the amp down if the power line voltage is too high.  This is a possibility if the amp shuts down when you rev the engine with the car standing still.  Test the voltage at the battery with a multimeter; it shouldn't go much higher than 14.4 volts when you rev the engine.  If it goes to 15 volts or more, have your vehicle serviced.

Third, it's possible that the amplifier's protective circuit is malfunctioning, shutting it down without excessive voltage.  If your multimeter reading is normal, but the amp still shuts down on engine rev with the car sitting still, then it's likely to be a problem in the amp.

Finally, how does the amplifier get its input signal?  Is it connected to an after-market head unit with RCA cables, or to factory speaker wiring using a line-out converter or high-level input?  The problem might be in the signal source, not the amplifier or sub.

Good luck!

Answer 2

chekc the wiring and if that checks out, you should chekc the battery and if that is fine, then you should get a capacitor.

Answer 3

I would check the ground wire to the amp, perhaps ground it at a different location with better metal contact, or try a thicker wire.  Pretty much every sub amp issue I have ever had has been fixed by doing this.