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Is there a solid 15/20 A 12v drop somewhere in the trunk?

Old Mar 6, 2010 | 12:01 PM
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Default Is there a solid 15/20 A 12v drop somewhere in the trunk?

Good day fellow audi enthusaists!

My a4 comes with the non bose non amped concert radio with 6 disc changer in the trunk and I think the system is just fine but lacks in the bass department.

I have an old JL Audio sub with amp screwed to the top and one of my old favorite tricks is to do a "local tap"....find a 12V drop somewhere for a useless feature like a power antenna, splice into one of the rear speakers and wire the entire amp locally.

Now the left rear speaker on this non bose concert system has 6 wires going in and I cant help but suspect that at least 2 of those are for the not installed factory amp.

Can a wiring guru lend their knowledge and help me figure out if this is true? Is there another available 12v lead in the trunk good enough for a 15a amp?

Thank you in advance and happy motoring!
 
Old Mar 6, 2010 | 03:09 PM
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I posted this at Audi World but I think it will help you out.

"As far as adding a sub, I couldn't handle not having one after picking up my A4 at the end of 2009. After much research and looking through the tech article found here http://www.audiworld.com/tech/elec.html, there is an easy way to get line-out to your sub amp and it's right at the driver's side rear speaker. This is taken from the tech article which I have added and taken out less important info.

First things first. This worked for me but do this at your own risk. I will not be held responsible if you screw something up. If you don't understand something, then ask before you start snipping wires. This installation does not require you to cut any of your car's wiring so please don't. Tapping means stripping a section of insulation off of the wiring leaving the bare copper wire showing at which point you can solder another wire to it and wrap your work with electrician's tape.

These wire colors worked for me but you may want to verify that they are the same before starting by looking at the back of your wiring harness off the stereo. My OEM stereo had a diagram stuck to it with the wiring diagram.

The rear amp is a smallish thing, normally attached to the rear left speaker in the rear deck plate. There is a connector plugged into the side of the speaker when you drop your drivers side rear seat down.

The brackets represent the slots that slid into the male harness end. The side with the outward piece is the piece I chose as the "top".

________[ ]________
(1) (2)
(3)
(4) (5)
(6)
(7) (8)
________[ ]________

1: White- Switch
2: Red-Blue lead to Right speaker
3: Brown-Red lead Right speaker
4: Red-Blue (thicker): 12v
5: Blue-Green Right pre-amp from head unit.
6: Red-Green Left pre-amp from head unit
7: Brown (thicker) Ground
8: 2 Brown-black Grounds for pre-amp leads.

In order to get line out, you just tap into the pre existing wiring using Scotch locks or stripping the wiring insulation and soldering the connection. These instructions will assume you are soldering the connections.

1. Take a set of RCA cables and cut one set of ends off making sure there is enough length to reach the amp.

2. Strip the end exposing about an inch of both the inner core and ground (outer metal sheathing). Do this for both ends then twist the grounds together from the left and right channel.

3. Strip the insulation off of the Blue/Green, Red/Green, and 1 of the Brown/Black wiring from the connector leading to the rear speaker using a razor knife. Do not cut the wires.

4. While you're under there, go ahead and strip the white wire on the connector for the amp's remote turn on.

5. Get a length of small gauge wire for your remote turn on and strip one end.

6. Get your connections ready for soldering by twisting the right RCA's inner core to the Blue/Green wire's stripped section. Then twist the left RCA's inner core to the Red/Green. Then the RCA's twisted ground from the left and right channel to Brown/Black. Finally twist the remote wire to the white wire.

7. Solder and tape up your work.

In order to get power to the amp, I ran a heavy gauge wire from the battery to the trunk. I ran ground to one of the bolts underneath the rear seat."

You could tap into the 12v at the connector plug but I don't know if it can handle a sub amp's current draw. Judging by it's small gauge, I wouldn't think so but it's up to you. You will soon find out when the fuse keeps popping when the bass hits. If it does, do not increase the fuse size in the panel as this will start fires. The best way is to run a heavier gauge wire directly from the battery with an in line fuse as close to the battery as possible. Good luck.
 

Last edited by Cybersombosis; Mar 6, 2010 at 03:13 PM.
Old Mar 6, 2010 | 05:18 PM
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PERFECT! You're da man.

Lemme go out there and see if I can get this thing working
 
Old Mar 6, 2010 | 07:33 PM
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Oh man...my car BANGS now =P

The little wiring is more than capable of supporting a 20AMP amp. It sends such clear signal that I had to turn the gain down so I dont go deaf.
 
Old Mar 6, 2010 | 07:42 PM
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Did you end up hooking up low level RCA's like the DIY or did you go with high level inputs from the speakers?

Doug
 
Old Mar 7, 2010 | 11:13 AM
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Originally Posted by CrazyPete
Oh man...my car BANGS now =P

The little wiring is more than capable of supporting a 20AMP amp. It sends such clear signal that I had to turn the gain down so I dont go deaf.
Wait... did you run the power cable for your amp through the stock power wire? How much power (rms) is your amp putting out?
 
Old Mar 7, 2010 | 11:03 PM
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It has 2 20 amp fuses. It is a component amp. It should have blown the fuse but it works just fine, even with the gains turned up. Hey, I am not complaining.
 
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