Trevkx125

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

Vrodman

I did a large write-up on this about 3 years ago for my 2011. Read through this:

https://mbworld.org/forums/w212-amg/...rade-w212.html

PeterUbers

Vrod is the man! Trust me when I say he knows a thing or two about audio and engineering!!!

Trevkx125

Many thanks Vrodman, I actually found all your info before I started, it was a great help so thank you!

I still can't work out why it is not working, would using a line out converter be better that the high level inputs on my amp?

Many thanks

Trev.

Vrodman

Line out versus speaker level out is always a better choice in terms of induced noise. I really can't say what is going on with your setup. Seems strange. I did see you used the same brown, white, and black wires I suggested. Perhaps your amp has an issue? Or perhaps switch settings on the amp? Do you know if your stock setup has the single or the dual flat subs? It turns out my 2011 (which I did the write up on) was a single flat sub while my newer 2015 has dual flat subs. I also recall that the wire colors changed slightly from my 2011 to my 2015 but unfortunately I don't remember to what colors.

Now you have a 2012 which is very close to the 2011 so I am surprised at your issues. I just don't know when they went from 1 flat sub to 2 which drove the color changes in the wires. If it was 2012, then maybe you have the wrong wires. Pretty sure if you take it to any reputable stereo installer they can figure it out for you and fix it for less than $100.

Good Luck

Trevkx125

Many thanks for your reply. Mine is the Biturbo and has the later set up with the start stop battery and 2 subs.... possibly the wires could be wrong but I don't really know how to find out!

I might try a LOC, I just haven't had the best of luck with them before with interference, admittedly using a cheap converter. Can anyone recommend one to try?

Many thanks

Trev.