what guage of wiring do i need?

Scott-Atah

Registered User
I'm not rich....and don't need the best, but don't want crap...so here's my setup and what i have planned.

my system:

HU: Alpine 7894
Speakers: Memphis 5x7s up front, stock in back
Amps: JBL600.1, Concept cc504 (35x2+75x2@4ohms)
Sub: Alpine Type R 12" (4+4ohm)

4guage from battery to fused distributor
8 guage out of hte distributor to each amp
8 guage grounds from each amp
 
4 guage?? Whew man.. planning on starting the car through the same wire? That's like jumper cable thick..

OK.. Look at the power rating of the speakers and calculate the peak current. The amps won't matter if they overdrive the speakers anyway. Or.. look at the power rating of the amps. The 12" sub will draw the most power.

Anyways, for the 5x7s. I'll say they max out at 80W peak and probably somewhere around 40W sustained which means about 3.5-7Amps peak current. 16-18G wire from the amp to the speaks is plenty sufficient for that.

Now, if your sub maxs out at lets say 200W, then you're looking at approx 200/12= 18Amps. 14Gwire is sufficient for that.
Now, back to your total load for your feeds to the amps.. Just sum up the peaks.. 7+7+7+7+18 = 46A.
Your 8G wire going from the battery to the amp is plenty big enough for that.. Now, if you already have the wire, just use it, but yours are plenty thick enough.
 
Actually, 4ga is about the minimum I would go with. If you are running an amplifier with an unregulated power supply (which most are) on only 12v, any loss of voltage is going to directly influence your output power. I have measured in excess of 2 volts drop in many installs by the time the power reaches the back of the car. Thats around a 16% loss of expensive power.
Since most car amps are around 50% efficient, The combined rated power of those amps could easily reach current draws of over 100amps. Something to think about when you are cranking that system.
 
Err, most car amps are fairly efficient, unless you are buying pyramid, jensen, and that crap...

Real amps are bench tested to make sure they put out the wattage they advertise
 
Fairly efficient is probably a good term. Think of it this way. If an amp was 100% efficient, it would run cold. All that heat that comes off of them is wasted efficiency, and most amps run pretty darn hot when you are using them near their rated power. The name brands you mentioned are not known for being top of the line models, but their design and efficiency is going to be very similar to any class a/b amp. Take these specs for instance: A Rockford Fosgate 201S puts out 255 watts at 14.3V 2ohms with 61.5% efficiency. If the voltage at the amp slumped to 11.5v due to small wiring, that power would drop to 205 watts. At the 14.3v power rating, the amp would draw 29 amps of current due to losses in efficiency.
 
Heh Going by the fuses on my amps.. they can Draw as much as 65 amps <dought it but still> 2x25amp on the alpine, 1x15amp on the Kenwood.. also i'm running 4ga for those two amps too (I did just have the 4 ga just for the alpine, the Kenwood came a long time after) Also going by the chart in the ISCA <?> Book or what ever, 4ga over the length i ran it was almost the minium..

Also glad i did.. I dont' know how you truely test for voltage drop (Amps off, Amps on/no music, Amps on/Music) But with the system off, I had like a .02 or was it 0.2 Voltage drop from the battery to the Trunk... Which ALOT of installers around here said is very good :)
 
Even with a tiny wire your voltage at the back with the system off will be very close to battery voltage. The real test is to crank the system and then measure. If you still hold a high constant voltage then you are doing well. The best way to check to see how much you are losing is to put one lead of your meter on each end of the wire you are testing. You will read the actual voltage drop across the wire while the system is playing.
 
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