Every spring while plant life begins to emerge, the car audio community enjoys its own waves of intense color and sound as a fresh crop of new project cars sees the streets for the first time. You'll see them at the increasing number of car shows, which will drive your desire to update your own ride. You will have some serious decisions to make. For instance, what gear and accessories will you want? The annual Car Audio & Electronics Directory Issue, out in June, will be your map for that journey. Our latest project since the Panasonic Stealth is on the road and will soon be on the pages of CA&E, which leads me to another serious decision where I need your help. What should my students and instructors build this year? Log onto www.mobiledynamics.com/special.html and let me know your choice.
Q| I am hooking up a system in my 2004 Trailblazer and am undecided on how to wire my amps. I have a JL Audio 1000/1 and a JL Audio e4300. Should I use 2-gauge wire and a distributor block with 2- to 4-gauge outputs, which would run to both amps? Or should I use 4-gauge wire to a distributor block with one 4-gauge wire to the 1000/1 and one 8-gauge wire to the e4300? The reason I am undecided is because I don't want to lose power to my sub amp by using 4-gauge wire and splitting it with another 4-gauge and 8-gauge wire. Which leads me to my next question: Is the 2-gauge wire necessary or would I get the same result with 4-gauge wire to a distributor block and then split it between one 8-gauge and one 4-gauge wire?Henry Villa
A| Even though figuring out how to power an amp is scientific enough, there are a variety of approaches, and more than one has merit. For some, the rule is to put in the biggest hunk of copper they can find-too bad about the huge ridge in the carpet. Others will buy bargain-bin wire that appears to be big, but in fact has a big jacket over a small conductor. I have seen documentation from an engineer who discovered that a low-end brand of 14-gauge speaker wire measured 0.043" in diameter instead of the required 0.0728". That would add up to slightly bigger than a 20-gauge wire! If something appears too good to be true ...
I use a set of rules for estimating the appropriate wiring that is based on a method many experienced professionals continue to use today. First, I look at the product. In the case of the e4300 amplifier, the power connections are intended to fit 4-gauge conductors. By this I mean "real 4-gauge conductors" instead of the thick jacket stuff-once the jacket is stripped away from the end of the wire, the copper that is exposed should almost fill the entire power connector. If it doesn't, you probably don't have real 4-gauge. If the amplifier was built with 4-gauge connectors, then you can safely assume that 4-gauge is the preferred wire to use even though the product info says "up to 4-gauge."
Next, I look at the power requirements. If the amplifier has a panel-mounted fuse holder, half your thinking is done. If not, you need to consider the power consumption the unit will require. If the e4300 is rated at 220 watts x 2 channels at its maximum, you can estimate that if it is only 50 percent efficient, the amplifier will need to take in 880 watts in order to deliver 440 watts of audio and a bunch of predictable heat. At 14.5 volts, 880 watts calculates out at 60 amperes of current draw at most, providing the amplifier isn't one of those competition amplifiers that can double its output a couple of times under extreme loads.
The 1000/1 is listed as 1,000 watts at 14.5 volts, but since it is a Class D amplifier, it should be at least 75 percent efficient, so I would be inclined to use a 100-amp fuse for that unit.