Car Stereos: sub not working, pioneer cd player, rca cables

Question
Hi I recently bought a pioneer deh-50ub headunit and have now hooked up a 1000 watt amp and an 800 watt sub, its all been wired correctly and I cant get any sound out of the sub, I changed the settings on teh headunit to work with amp and sub and still cant get any sound. Any ideas? cheers Fraser

Answer
Hi,

There's such a variety of things that can cause this, that it might be hard to pin it down unless you have the means to substitute other components. Here's what I'd do for troubleshooting:

Make sure the RCA cables are plugged into "input" jacks, not "output" jacks, at the amplifier.  Also, double-check the speaker wire connections; sometimes there's a poor connection at the speaker terminal  on the sub box, or the wire may have become disconnected from the subwoofer inside the box.  If there's a crossover filter on the amplifier, make sure it's set for "low pass" or "full".

You might try unplugging the RCA cables from the amp, and substitute another audio source.  For example, you can buy a cable with a stereo mini "headphone" plug at one end, and two RCA plugs at the other, and use it to connect an iPod or portable CD player directly to the amp inputs.  This will help you determine whether the problem originates with the Pioneer CD player, or the amplifier.

If you have a digital multimeter available, it allows much more accurate troubleshooting.  You can set it for AC volts, and test the speaker terminals at the amplifier.  If you're getting varied voltage readings when music is playing, then you'll know the amplifier is operating and the trouble is in the sub or sub wiring.  If there's no output at the speaker terminals, you can test for a lower AC voltage at the RCA plugs (test the voltage on the center pin, using the outer shield for ground).  If you have voltage there, and no output voltage at the speaker terminals, then the problem's in the amplifier.  You can also test the resistance reading between the positive and negative terminals on the sub box.  If the resistance reads below 2 ohms, your sub may have a shorted voice coil; if you get a very high reading or there's no continuity, then the sub may have an open voice coil or there may be a wiring problem.

Good luck!

Brian