signal lead to amp

[rik89]

I've just wired my sub and amp in and just need to know which wire on the (bmw) radio harness to tap into for my signal lead to the amp, i tried the blue one(its usually blue in the uk) on my adaptor harness and no joy. so I'll get the signal from the oem harness.
help much appreciated

[hotmilk400]

... not alot of info..
what is the model of your car.
also, what year it is (they change colors all the time)
what stock speaker setup do you have (4 speakers, 6 speakesr, 10 speaker system) this is important because it will tell me if you have a stock amp, or 2 stock amps to pull a wire from.

stock radio?

what are you looking for? signal lead? if i had to take a guess, the secondary power lead? or are you looking for the wire/wires that will give sound to your amp? (sorry, i heard these wires called everything already)

also, to save you a huge headache. if you are putting the amp in the trunk, which i figured you would be, there might be an amp already in the trunk(stock with the car). this amp is only a little thing located commonly behind the left trunk wall panel (under your antenna) . you can disconnect that amp or tap off of it very easy, and you do not even need to worry about running new wires (depending on the amp and which speakers you wanna hook up) you will still need to run a power line from your battery to it tho, there is no getting past that. and you should run RCA cables from the radio to the amp. the only other cable left is the 2nd power lead.

[rik89]

er ok, it's a base model 318ti 1997 m44. 6 speakers.aftermarket radio- acoustic solutions ics 160

Im just looking for the wire that tells the amp to switch on(signal lead)

Ive found my head unit book now, tells me which pin is used for it so I should be ok running it from that wire.

If I run into further problems I shall let you know, so thanks for the help.

on a side note, what is the approximate max safe current that can be drawn from the stock battery? my amp is 600w rms and it uses it! so may look into a second battery in the boot at some point.

cheers, rik

[hotmilk400]

1) the 1995 – 1997, 6 speaker models have the same wire colors. (they change at 98)
the color should be white. White, weather you pull it off at the antenna in the trunk, or at your radio, is the antenna amplifier power cable (basically the same thing you need, this wire turns on things when the radio is on)

2) two batteries are not really an option. the batteries will drain each other and you will end up with dead batteries very often unless an expensive kit is installed to allowed them to work together. also, the lack of space for a 2nd battery is a issue. The eaiest and cheapest upgrade would be to upgrade from the stock battery to a battery with higher current.

a 600 watt amp will be fine even with the stock battery. the amps do not drawn current from the battery as much as they do from the alternator. The battery is mostly used just to start up the car, and to give things like your amp alittle space to drawn more power without bogging down your car. There will be no issue with power, as your batterys are about 50 AH – 60 AH . this means, a 55AH battery can drawn 55 amps for 1 hour or 5.5 amps for 10 hours. (or whatever inbetween) .

55 amps is about 660 watts (relative to your car, which is 12volts DC). Meaning, without the car being on, the Minimum amout of time you can run the amp is about 1 hour with a stock battery. Since the amp drawns about 300 watts – 400 watts with normal to loud playing, you are looking at something like 2 hours without your car being turned out.. (don’t worry about battery size ) when you are driving your car, the alternator is making more then enough to cover the amp playing.

since you are looking at a larger amp (draws 50 amps), you will need to make sure the wire you run to the amp to power the amp is ATLEAST 6 AGW (I am not sure if you guys use AWG in the UK (something like 13,300mm^2) I don’t remember what other countries use anymore other then the metric system to measure the gauge of wire. (I hope that helps)

you need to run this wire right from the battery to the amp. You MUST get a fuse or circuit breaker that connects to the wire right after it connects to the battery. If you do not have at least a fuse, you are asking for serious trouble. The smallest nick in the wire will cause a huge fire because when the wire shorts out, the entire wire will get red hot, and anything touching it will start on fire (done it before) ..

also, because this is a 600 watt amp used for a SUB, you MUST have a Capacitor. Basically this is your 2nd battery in not so many words. You will need one rated at atleast 1000 watts (safer to get one higher) .. what a CAP does is provides the amp with power instantly. The CAP strores up current, and then when the amp hits a loud note, it will release the power store up. Not only will this sound better, but if you do not use a CAP, then you can cause A LOT of damage to your cars internal computer. Car amps draw such a large amount of power that it literally steals it form other things like headlights or your internal computer. I have a 1000 watt system, 10 speakers. The cap is rated for 2000 watts, and my headlights will still blink to the music. Without it, the headlights would be almost useless.

get a cap that is rated 1 fraud or 1000 watts.

^^ hope that wasnt to much info packed into one comment.. haha.. if you need anything else, please ask it.. =]

also, you car does not come stock with either the amp or subwoofer amp =/ .. i think that was the 10 speaker systems for you year, and all 98 + models