QuestionI have a 1997 Hyundai Tiburon with one 12in Sony Xplod speaker running 1000 watts Sony Xplod amp. When i cut my lights on they dims when bass hits. I also have 1.6 farad cap hooked up too. How can i solve this problem? Should i go lower on the amp or what?
AnswerHi,
I apologize for the long delay in answering your question.
It's not uncommon to see dimming lights when playing a high-powered audio system; it's annoying, but usually harmless unless it's accompanied by other problems. You're seeing the results of a voltage drop caused by the amplifier's sudden demand for current on musical peaks. This might be due to resistance in the factory wiring.
Every wire and electrical connection in the vehicle has a certain amount of resistance. When current flows through a wire, the resistance causes the voltage to drop. If you have high resistance, or high current, then you lose a lot of voltage; low current or low resistance results in lower voltage drop. When the extra current required by the amplifier is flowing through the same wire that's used by another vehicle accessory, then the voltage drop that's caused by the amp will affect the other accessory as well. In the case of the headlights, the effect of a voltage drop is easy to see: lower voltage = dimmer lights.
If you want less voltage drop, you either need to reduce the current or reduce the resistance. There isn't much you can do about reducing the current demand from the amplifier, if you don't want to affect the audio output; turning down the gain will make the amp use less current, but you'll get less sound as well. Another option is to switch to a "class D" amplifier; these are more efficient than class AB amps like your Sony, so they don't require as much power from the vehicle's charging system to produce the same level of output.
A more practical option is to try reducing the resistance in the vehicle wiring circuit. That doesn't mean you have to re-wire your headlights. Instead, you're going to want to focus on those parts of the circuit that are used by both the lighting system and the amplifier. There are three main vehicle wires that are carrying the current of both systems:
-The main power wire between the alternator's output and the positive battery terminal. Under normal conditions, when the engine is running, all electrical power is produced by the alternator. The amplifier's power wire is connected to the battery terminal, but the current it's using doesn't come from the battery; it's coming through the wire from the alternator. A voltage drop in this wire will affect all the other vehicle systems too, including the lights.
-The wire between the negative battery terminal and the vehicle's chassis. When you installed the amplifier, you probably didn't run the amp's ground wire all the way up to the battery; you would have connected it to the vehicle chassis at some point near the amp's mounting location. The reason you can do this is that the vehicle chassis is connected to the negative battery terminal through the factory wire. Most other vehicle accessories, including the lights, are also grounded to the vehicle chassis; so the current of all these accessories flows through the same wire. Remember that the current flowing through the ground wire is always exactly the same as the current flowing through the positive power wire.
-The wire between the engine block and the negative battery terminal. As I mentioned, the alternator is the main source of electrical power when the engine is running. You can see the alternator's positive power terminal, but it doesn't have a negative terminal. That's because the metal case of the alternator is the negative connection. When the engine is running, all the current generated by the alternator flows back to the alternator case, bolted to the engine block. Therefore, it's important that the engine block has a good electrical connection with the vehicle's chassis ground. Sometimes this is a wire or braided metal strap between the engine block and the chassis; sometimes it's a wire from the engine block to the negative battery terminal. Either way, it's a very important connection, and a voltage drop here will affect all the vehicle accessories.
To reduce the resistance through these three wires, the first thing you should do is make sure the connection points are clean, tight and free of corrosion. Make sure your battery terminals are tightly connected--you shouldn't be able to move them by hand at all. If there's corrosion, take them apart and clean them. Look for the factory wires I listed above; see if you can find the connections at the chassis and the engine block. Are they loose, rusty, or corroded?
Next, you might consider upgrading the factory wires. Vehicle manufacturers are very concerned with weight; they don't often use a larger wire than they need. That means the factory wire may be too small to support the extra current from the audio system, in addition to the vehicle's normal electrical requirements. If needed, you can install your own wires in place of, or in addition to, the factory wires. You don't have to remove the stock wires, or even follow the same wiring path; but make certain you don't put a wire where it's going to rest against something hot, or interfere with a moving part. Also, any wire you connect to the positive battery terminal should have a fuse installed, as close as possible to the battery terminal. Wires connected to the negative battery terminal don't need a fuse.
Finally, it's possible that your vehicle's alternator doesn't have enough capacity to supply your amplifier, in addition to the electrical load from the vehicle systems. I doubt it, though; you don't have an extremely high-powered system, and a typical stock alternator should be able to support it without much trouble. However, if a wiring system upgrade doesn't help, you may want to have the alternator tested to make sure it's working properly. If it's just too small for your system, then you might be able to find an upgraded alternator, with more current capacity, that will fit your vehicle. As I mentioned, though, the dimming is probably harmless; so you'll have to decide whether it's worth the expense of an alternator upgrade to make it go away.
Hope this helps!
Brian
