Help with Sub Wiring please!
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 23
Likes: 5
E63 BiTurbo
Help with Sub Wiring please!
Hi, I was hoping someone might be able to help with my 2012 E63 with the Harman Kardon Logic 7.
After reading lots of great info on here about adding a separate amp and sub to my logic 7 system I installed a 12" JBL at the weekend with a matching JBL amp, my problem is the RCA signal just puts my amp into protection mode for some reason. It's a brand new amp and I tried it with a different signal and it worked fine, so it's not faulty.
I have tapped the small White & Brown wires from the original amp on the rear deck and the medium black for the turn on signal. The problem seems to be with the earth of the RCA signal, as soon as it touches the amp the unit goes into protection mode. The original amp/subs work fine.
Have you got any ideas? I have had to use the high level output (Green/Green Brown) to get it to work, but it doesn't sound as good as it should. Is there somewhere else I could try to tap the signal, possibly the other amp?
Many thanks all!
Cheers.
Trev
After reading lots of great info on here about adding a separate amp and sub to my logic 7 system I installed a 12" JBL at the weekend with a matching JBL amp, my problem is the RCA signal just puts my amp into protection mode for some reason. It's a brand new amp and I tried it with a different signal and it worked fine, so it's not faulty.
I have tapped the small White & Brown wires from the original amp on the rear deck and the medium black for the turn on signal. The problem seems to be with the earth of the RCA signal, as soon as it touches the amp the unit goes into protection mode. The original amp/subs work fine.
Have you got any ideas? I have had to use the high level output (Green/Green Brown) to get it to work, but it doesn't sound as good as it should. Is there somewhere else I could try to tap the signal, possibly the other amp?
Many thanks all!
Cheers.
Trev
Super Member
Joined: May 2009
Posts: 673
Likes: 27
From: Frederick
2000 ML320, 2005 E320 CDI
Sounds as though you have power going to your line in. Have you tried tapping the sub wires and running it to your high level inputs or putting a LOC from the sub line so you can connect your RCAs there? I have a JL Amp so I ran Hi level inputs from the sub (which I disconnected).
Newbie
Joined: Aug 2019
Posts: 5
Likes: 2
From: El Paso
19' AMG GT53, GLE350
Im sure you can run the RCAs off the low output from the logic7 amp, you would have to figure out which wires connect to the rear stock sub. But it almost sounds like its more of a powering issue, you should check where your remote wire is connected too needs to be connected to 12v that powers on and off with the car. Possibly the 12v lighter outlet. Good luck
Last edited by JQW212; Aug 5, 2019 at 04:53 AM.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 23
Likes: 5
E63 BiTurbo
Thanks all. I have connected the amp using the high level inputs, it just doesn't sound as good as it could. I always dound doing the RCA route is much better.
It does seem strange it doesn't work as the stock subs do work ok so surely the RCA output must be ok?
I need to figure out which wires to tap for the RCA lines from the main amp behind the side panel and try that.......... It's a big wiring plug so lots of wires!
Cheers
Trev.
It does seem strange it doesn't work as the stock subs do work ok so surely the RCA output must be ok?
I need to figure out which wires to tap for the RCA lines from the main amp behind the side panel and try that.......... It's a big wiring plug so lots of wires!
Cheers
Trev.
Junior Member
Joined: Mar 2019
Posts: 40
Likes: 13
Cls550 2016
Check my post on adding a subwoofer under CLS or c218 forum. I just installed a 10 inch JL shallow mount with an Alpine amp. I tapped the signal from the rear deck amp using the small whiite wire for postive and the brown for negative. Next you need to buy an IEC 18 awg wire with RCA male. The small white wire will be hook up to the copper color wire from the IEC 18 awg and the silver color wire goes to the brown wire. After that just hook up the male RCA to a female to two males RCA adapter. You can check with a voltmeter and see if you have 5v on each of the male RCA. The rear amp only has one signal so you have to split the signal into two for your after market amp. Same thing happen to my Alpine amp. JL shallow mount ten inch produce tight punchy bass not bloated. If you need help, just PM me. Btw, you dont need to add an LOC or high level input. Also you can search an old post by RNBRAD on adding a subwoofer.
Last edited by FirstCLS550; Aug 6, 2019 at 01:26 AM.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 23
Likes: 5
E63 BiTurbo
Im sure you can run the RCAs off the low output from the logic7 amp, you would have to figure out which wires connect to the rear stock sub. But it almost sounds like its more of a powering issue, you should check where your remote wire is connected too needs to be connected to 12v that powers on and off with the car. Possibly the 12v lighter outlet. Good luck
Cheers
Trev
