Keeping an Ear Out for Tuning Issues

After a while, you’ll probably start to notice things that are amiss with your system. In fact, really experienced car audio tuners can simply listen to a system and tell where the problems lie. If you’re a beginner you can’t do that, but there are some things that you can listen for and correct. Here are a few of them.

Bass in the hack

One of the obstacles to getting great sound in a car is that subwoofers are almost always mounted in the rear of a vehicle. The rear portion of a vehicle is usually the only place where there’s room for subs and their bulky enclosures (although some hardcore car audio enthusiasts have been known to cram subs in doors or even floorboards). 

Most likely, your subwoofers are behind you, whereas the speakers that take over for the subs frequency-wise, the midranges, are mounted close to you in the doors. Often this can cause a disjointed sound — the dreaded bass-in-the- back syndrome — in which it’s very noticeable that the low bass is coming from behind you. It sounds like the bass drum and bass guitar are in the trunk, whereas the rest of the instruments are on the soundstage in front of you.

This can be a difficult problem to correct, but by crossing your front midranges’ drivers as low as possible, you can sometimes minimize this effect. This also depends on the type of music you listen to. As mentioned earlier, if you listen to bass-heavy music, you want to be careful about crossing over your mids too low. Otherwise, they will distort because they’re not designed to handle extremely low bass, and they could even be damaged. (Refer to the “Setting gains and crossover points by ear” section earlier in this chapter for more on how to set crossover points.)

Out of phase speaker Wiring

Wiring a speaker in reverse polarity or out of phase — meaning that the cone moves in when it’s supposed to move out and vice versa — greatly diminishes sound output. When two speakers are wired out of phase with one another — say two midranges in each door, facing one another — the push-pull sound waves they generate effectively cancel each other out. The way you’ll detect that something is amiss is that the speakers won’t produce the volume that they should. If the front speakers are wired out of phase, the rear speakers (if you have them) may sound louder.

If you installed the system yourself, make sure the speakers are all wired correctly, with the positive wire connected to the positive speaker terminal and the negative wire connected to the negative speaker terminal. If you had the system installed at a shop and you suspect that something’s not right, take your car back and ask them to check the polarity of the speakers.

Sometimes subwoofers can actually sound better when they are out of phase, although if you are using more than one sub, they must all operate out of phase if any of them do. In fact, some head units that have built-in subwoofer crossovers and controls allow you to reverse the phase of the subs at the push of a button.

Distortion

Distortion is anything that is not part of the original audio signal reproduced by a speaker, and it is noticeable when you listen to any music that you’re familiar with. It could be an acoustic guitar that sounds too tinny, cymbals 

that sound too bright, or a bass note that sounds too tubby or just doesn’t have the tight sound that it should. Distortion can be caused by many things, but it’s mainly due to a component trying to do something it wasn’t designed to do. This could include driving an amplifier past its design limits, mis-matching gains, or crossing over a speaker such as a midrange too low.

The list goes on and on.

The best way to isolate distortion is through the process of elimination. For example, if you hear distortion coming from your midrange speakers even at low volumes, it could be because the crossover point is too low for a midrange. So check the crossover point and make it higher. If that doesn’t do the trick, make sure your gains are properly set. If that doesn’t do it, maybe the amp is overpowering or underpowering the speaker. You have to rule out one potential cause before you move on to another. To check the crossover points and gain settings, refer to the section “Setting gain and crossover points by ear” earlier in this chapter. If adjusting the crossover points and gains doesn’t work and you suspect that the problem is with the amplifier, you won’t know unless you swap out the amp.