Just completed my first install adding a subwoofer and amp to my HK logic 7 sound system. This install is much easier if your car has a second battery in the trunk. I ran my hot wire positive and ground to the second battery in the trunk no issues here. In order to get the signal for my Alpine amp and remote turn on, I tapped into the factory amp(N40/9) located just below the rear decklid in the trunk. There should be a plug with 9 or ten wires going into the amp. With this method you don't need to buy a LOC, the signal is before the amp but only one signal is going into the amp. The remote wire is black. The signal positive is a small white wire and just below it is the brown wire negative. You will need to use both wires for the signal going into my Alpine amp. This is probably the hardest part of the installation. There is not much space to tap three wires into that plug. It is very doable. Just take your time. Next I used one bare RCA wire with a male plug exposing the positive and negative. I got this from Amazon. The white wire will be hooking to the copper and the brown will go to the silver. After that I attach that male RCA to the Y RCA adaptor one female to two males. Most amps these days need two signals for left and right. I checked both center pins for 5-6 V before hooking it up to my Alpine amp. Now I have that great thump, punchy, and tight bass. Amazing sound, I need at least 30 hours for the break in period. Also, I want to thank RNBRAD and jonUFO2 for their help with this installation.
Setup and materials
1. Alpine MRV500 watts 2ohms mono
2. JL AUDIO 10 inch sub box CS110lg-TW3



3. ROCKFORD FOSGATE 8G wire kit
4. T tap 3
5. IEC 18g wire RCA with male one wire needed
6. Y adaptor 2 RCA male to one female
7. Dynamat trunk area, spare tire

 

That's the only con I have on the CLS, the HK logic 7 sound system could be better. I think a new would boost it significantly. What does your system sound like now?

 

A lot better than before, my wife has a Tesla model 3 that came with a pretty nice subwoofer. I compared both cars sound system and the Tesla model 3 definitely sound better. I think the HK logic 7 just needs a subwoofer. Mine is a sealed shallow box made by JL. I think ported enclosures will sound louder but the bass to me is bloated. I like tight and accurate punchy bass. Hope that helps.

 

Thanks for your help on this. I did a really rough install to verify hookups and it works for me too. I left that connector i tapped into undone as it seems from the diagram it only powers the stock sub. I also agree about the subs.

For the taps I have done it both ways, into the left rear (I went there to put capacitors on the rear deck surround sound), and I have done it now by tapping this way, and this way is easier. I would recommend using the new style with the spade connector for the joining wire. It takes up less space and seems stronger. Now that I've done the rough install I'm going to clean up the install with some speaker wire on all those connectors and finalize the AMP location.

Here is what I wrote about the rough install and feedback of the subwoofer install. I went with dual 10" jl w0v3. Powered by a hifonics hercules rated ~750w into 2ohm and 1 ohm stable. I've had it from high school!

I am trying to figure out the best place to mount the amplifier. Thinking either to a wood board then to the ceiling of the trunk or the floor and build farings out of CF for the sides of the trunk. Part of me thinks the trunk ceiling is better since all of the wires are there. My amp is about twice the length of that one. I think around 19" by 10".

My thoughts are the crossovers and signal seem to be great. I tested the crossovers previously and 80hz and less goes to sub from rears, and 60hz and lower from the fronts to the subs. I am unsure about the surround speakers, iirc they were played until about 400hz. There may be a gap there or they may have played to the factory subwoofer but I don't recall them putting out audible output less than 400hz.

This is such an easy install. Super easy to pick up and integrate with the stock system really well.