Favorite Car Audio Myths
Here's a list of my favorite car audio myths in no particular order.
1. Amplifiers should be grounded at the battery
Generally the battery is the worst place to ground an amplifier. The battery is where all of the electrical noise from the vehicle's various parts ends up. Like a noise garbage disposal. Connecting your audio components to this noise hub is a bad idea.
2. Adding a second battery to the vehicle will ease the load on the alternator
A second battery will increase the load on the alternator, not decrease it. With the vehicle running the second battery becomes another load for the alternator to charge. Second batteries are only good for engine off listening time.
3. Ground all of your audio components at the same place to eliminate noise
Sometimes this works and sometimes it makes the problem worse. When you ground any current carrying component to the vehicle you create a circular field at that point. Poorly designed audio components could pick up this field and introduce it as noise into the system. When this is the case it's a good idea to separate your components by six inches or more. The higher the current (large amps), the more space I recommend.
4. Routing power cables on the opposite side of the signal cables will prevent noise
Maybe. It will prevent the signal cables from picking up noise inductively from the power cables. But it won't prevent them from picking up noise from the vehicle's chassis or from other electronic components along their path. It's a good practice but doesn't guarantee noise pickup.
5. A high output alternator will reduce the chance of noise
Actually it's the opposite. The larger the alternator the greater the noise output. The noise increases with the power output of the alternator.
6. Power capacitors should be fused
The purpose of a car audio capacitor is to deliver large amounts of current very quickly (faster than a battery is capable of). Adding a fuse, which is just a short length of very small wire, will slow down this current delivery. And because capacitors can discharge so quickly the fuse wouldn't blow before the capacitor has discharged.
7. Adding more speakers will increase the sound quality
Volume, maybe. Sound quality, no. The more speakers you add to a system the greater the problems you will have due to speaker interaction. Each speaker is a little wave producer and when the waves from one speaker meet those of another speaker the results are peaks and dips in the response. Generally less is more when looking for sound quality. Look to the car audio competition finals winners and you'll see that they use a small number of high quality speakers.
8. Turning up all of the frequencies on an equalizer will increase the system volume
The system volume is based on many factors including system power and speaker sensitivity. The purpose of an equalizer is to compensate for vehicle specific problems and not as a general volume control. Boosting all of the frequencies won't make your system louder, only more distorted.
9. Tweeters should be placed as high up as possible
Tweeters should be placed as near to the midrange/woofer as possible in most cases. The tweeter and the midrange/woofer are a matched pair and shouldn't be separated. Imagine an electric guitar which has a wide acoustical range. If the guitar is playing a riff in the frequency range of the woofer and then switches to a riff in the frequency range of the tweeter you'll likely notice the position of the guitar jump. Now if the tweeter is placed near the woofer the guitar position will remain in place. Better installers can make a tweeter that is separated sound correct but a much safer bet is to leave the set together.
10. An amplifier's gain control should be set to maximum to get more volume
The purpose of the gain control is to match the output level of the component before it (head unit, equalizer, crossover, etc.) Since car audio manufacturers don't use a standard output level like home audio manufacturers do it is necessary to have an adjustable input. Adjusting the gain too high will only cause more distortion in the amplifier's output. Since our ears perceive distorted and painful sounds as louder this is a myth that has perpetuated.
Bottom line: Be careful who you listen to and what you believe (good advice for life too). There are plenty of folks inside and outside the car audio realm that will simply make something up if they don't know the answer (don't want to look stupid). Then there are those that have been told a lie, accepted it as truth, and passed it along. When in doubt, get a second opinion.
