[jgentry]

Due to the lack of information available for my specific audio setup, I figured it was my duty to record my findings for those of you wanting to add an aftermarket amp and sub to your system. I should mention that this forum has been very helpful but didn’t have one big DIY that I was looking for and it was always a little vague as to whether the content was for a stock, hifi or HK system or for what model of BMW it was targeted.

Here’s my setup:
2013 BMW 335i xDrive (F30) with the Harmon Kardon sound system

I had a 10” JL Audio (CS110RG-W3v3: Single 10W3v3 PowerWedge, Sealed, 2 Ω) subwoofer system that I had taken out of my previous car. The darn thing was just sitting in my garage looking at me, wondering why I wouldn’t install it in my F30. I finally got the courage after reading this post (http://www.f30post.com/forums/showthread.php?t=865182). I hit up Technic for details on the harness and line output converter or LOC (LC2i, specifically). Here was his reply on the subject (used with permission from Technic):

The F30 HK harness/LC2i to add an aftermarket amp to your OEM amp to power either a trunk sub or aftermarket underseat woofers is $145 shipped in the USA. Add $30 for outside the USA Shipping is 3-4 business days after payment. No shipping on weekends.

The LC2i active LOC is used in your particular OEM system due to the 35V+ peaks of the OEM amp woofer outputs. No remote turn on is possible with the OEM amp as all its outputs are Class D -no current signal sensing circuits can trigger with those.


I received the LC2i and harness within 1 week of ordering it from Technic. Below is a wiring diagram and picture of the harness (also used with permission from Technic):



First off, we need to remove pretty much every carpet panel from the trunk. The left-side carpet panel is connected to a 12V accessory plug, once the panel is initially free, you can unplug the two wires from the back of the accessory plug.



You will also need to remove the back seat panels next to each seat. To remove, simply fold down both back seats and then get a hand around the top of the cushion and pull. It should pop out pretty easily.



While taking off the carpet panels, you’ll see that they are all attached with black plastic “bolts”. I totally destroyed one of these before I could see how it works. There is a very thin disk that you can get a very flat screwdriver underneath. Once you pull out the middle part, the rest of the bolt comes out pretty easily. The picture below shows one of these “bolts” with the center portion popped out.



Also, you’ll need a size 40 (T-40) Torx bit to unscrew the tie-down hooks (the plastic caps pry off very easily).



The battery is located on the right side of the trunk (see those large red wires?).



The HK unit is located on the left side of the trunk. That large bundle of wires terminates in the plug that Technic’s harness will connect to.



The 20-pin connector has a sliding latch on it, simply slide it from left to right to detach. There are grooves in the plastic housing that will pull it away from the connections when you do the L-to-R motion.



The harness provided by Technic is a perfect match. Don’t worry, you don’t need to be forceful with the connector, it will only fit one way. Make sure the housing is slid all the way to the right, place the male and female together and then slide right-to-left and it should latch itself, repeat for the other side of the harness. I then tucked all the extra wire underneath, there’s plenty of space below. Here is where I want to make a note about the harness itself. Given the wiring diagram, you might be tempted to go tap into the wires without Technic’s harness. I should warn you, the wires down there are VERY TIGHT, as in no extra slack in the wires. I found this out when I was wiring in the remote-in for the amp and LOC (more on that later). The harness that Technic provides is very good quality, wired very neatly; I felt bad when I had to cut the high-level speaker output wires so as to extend them (I didn’t want to mount the LOC right next to the harness since there are some knobs on the LOC to tune the bass output and I wanted easy access). That white plug that is sticking out in the picture below connects to the high-level inputs on the LOC. I ran the newly-soldered wires around to the place where I mounted the LOC. Note that Technic’s harness allows for driving the OEM subs with an aftermarket amp (he even provides the plug for it). I decided to leave them connected to the OEM amp, I only wanted to add a subwoofer to my setup.



I ended up mounting the amp and LOC to the right rear seat because the amp wouldn’t really fit anywhere else. Also, I’m very paranoid about drilling into my trunk fearing that I’ll hit the gas tank or cut a wire. The seats seemed pretty safe. Note that they do have a metal backing so you’ll need to pre-drill all holes. I made sure the seat could still be latched with the amp in place (don’t mount it too high).



Now it’s time for running the power wires from the battery to the amp and LOC. I ended up buying two Car Toys install kits, one 8 Gauge for the amp and one 10 Gauge for the LOC. 8 Gauge was a little overkill for my amp but I want to leave room for upgrading the amp in the future, 10 Gauge is more than enough for the LOC. Both came with fuses that you want to connect as close as possible to the battery in case of a peak current event. I ended up connecting both directly to the positive battery terminal and then routed them back to where I mounted the amp and LOC. In the picture below, the blue wire is the 12V for the LOC and the see-through red cable is the wire providing 12V for the amp. Be careful here, I don’t know how much damage a 12V shock could do but I do recall a socket wrench having a pretty large notch taken out of it when I accidentally shorted the two terminals together on my first car in high school.



Sorry for not taking a picture of it but I connected the ground wire to a nut that was holding down the combo box in the middle of the trunk, right next to the fuses. Below is a picture of said fuses with the wiring in the background. Be sure to leave enough slack for the back seat to fold down and up without straining the wires.



Now the hard part (but easy for you now that I’ve found this). Technic pointed me to an M3 forum where they talked about where to find the remote-in wire that is used to tell the amp and LOC when to turn on/off. The wire wasn’t there, I searched all over the place and couldn’t find it. Not wanting to take the dash apart to get at the back of the iDrive (pin 13, by the way), I started plugging away at Google to see if anyone else solved this problem. Indeed they had, kind of. I found this forum entry (http://www.f30post.com/forums/showthread.php?t=729073) post 18 that talked about a little black wire (which wasn’t there on my system) but they also mentioned a red and white wire in post 20 which was. It is a little hard to see in the picture below (ignore the speaker wire, that is the wire I used to extend the high-level wires for the LOC) but it should be unmistakable once you find it. It is in the same big bundle of wires that includes the high-level output wires that the harness tapped into. Most of the wires are twisted pairs. Since the info on this wire was pretty vague, I decided to throw a voltmeter on it to be sure. It read 12V, score! However, I wasn’t sure if it ever turned off so I waited. And waited. And waited. Then I closed all of my doors and waited some more. Eventually the trunk light turned off and I tried again. Wha-La, 0V (well, 2V but it was dropping as I watched, close enough I hope, I’m guessing 2V is close enough to 0V to trip the relay in the amp and LOC). I ended up splicing into this wire and running this back up to the amp and LOC. As I mentioned before, the wires in this bundle are very tight. I had to tug a LOT to get enough slack to wire in the remote-in wire to the amp/LOC.



Finish up all remaining connections (i.e. RCA from LOC to amp). Now all you have to do is remember how to put the trunk panels back together. When installing the back seat cushions, be sure to line up the hooks on the cushion with the hook receivers mounted to the car. Once aligned, give it a firm jab and it should re-connect. The plastic bolts should go in in reverse order that they came out; outer housing first, then center pin.

Below is the finished product. The speaker itself looks a little clunky but I wanted the ability to remove it if I needed extra trunk space. Maybe I can change out the carpet on it to match the trunk.



Now on to tuning, reply below if you have any thoughts on this. There are spots to tune the LOC, the amp and, of course, the EQ on the iDrive interface itself. Any recommendations on how to get the best sound out of this? I’ve been told you want to tune the low-level signal since the gain on it is pretty low.

I wanted to again thank Technic for providing the harness and LOC as well as the wiring diagram. Please send him a PM if you want to order anything.

[IndividualF30]

Great One!!

I will be doing this in the next week or so myself, good to see I won't be the first.

I will be mounting the amp on my sub woofer box, so I will be able to some pics of a variant of this guide soon too.

[CLittle]

Cool write up, thanks for taking the time to take so many pics and for doing a well written how-to.

With on demand alternator decoupling when not needed, I heard that our cars have a special voltage converter to maintain the 14v to critical components such as the HK audio system, while non voltage sensitive equipment drop to battery voltage of 12v. Can anyone else confirm this? Where do you tap the power for 14v and if not, will the sub output fluctuate?

[jgentry]

Huh, no clue. Every 'hot' wire I probed was 12-12.5V.

[CLittle]

http://www.f30post.com/forums/showthread.php?t=858575

This sticky has a link to general vehicle electronics, item 16 on page 6 is the dc/dc converter but I didn't recognize it from the photos you have above. The purpose is explained on page 19. If it sounds good, I wouldn't sweat it. Just thought I'd throw it out there if you run into an issue with sub output varying.

[jgentry]

Still happy with the sub. I haven't finished tuning the amp and LOC but I'm getting close.

My only complaint now deals with the back window taillight enclosure rattling every time the bass hits. Anybody else resolve this?

[IndividualF30]

Just been checking out my HK setup. It appears the amp gets power directly from Fuse 123 (40A) and the remote on/off to the amp from Fuse 159 (5A). I want to pull the fuses just to confirm this though. I can't see the DC/DC Voltage converter referred to in previous articles either, so looks like an improved amp.

It appears the strip of fuses from 154-159 seem to be iDrive Remote on/off from an internal relay in the fuse block, but want to do some probing to confirm this.

If I can find the correct spade connector for the fuse box, it could make for a very neat, no wire tapping hookup of the remote on/off wire for the LC2i and Sub amplifier.

[IndividualF30]

OK. I have been probing around and found that Fuse 159 is the remote wire to the HK amp (Red/White stripe). Removing the fuse and unplugging from the Amp end seems to reveal this fuse is only used for the remote to the amp. Simply use an add-a-fuse and you are done with the remote. No tapping pin-13 on the iDrive.

On another note. I found about 60% of the fuses in the fuse box in the trunk (boot) are actually populated without any wires connecting to them. I removed about 20 unused fuses from the box. It looks very bare now.

On another note, the new NBT Nav Pro configs appear to not have a combox. I have Internet, Ext Connectivity, Nav Pro, Reversing Camera, Surround view, and still no combox. This spot makes the perfect location for the LC2i.

[jgentry]

Probably the same red/white wire I tapped back by the amp. I wonder if it would be easier to splice into near the fuse box. Shorter wire run for sure.

[Technic]

To clarify: the HK OEM amp -and any BMW OEM amp connected to a MOST network- do not have any wired remote turn on signal. MOST OEM amps turn on/off via MOST message via the fiber optics cables.

The iDrive unit pin 13 is the OEM wired remote turn on for the OEM radio antenna amplifier. This is the wired remote turn on signal that shall be used with aftermarket audio amps and processors via an aftermarket relay so it is isolated and protected from such aftermarket equipment.

Originally Posted by IndividualF30

Just been checking out my HK setup. It appears the amp gets power directly from Fuse 123 (40A) and the remote on/off to the amp from Fuse 159 (5A). I want to pull the fuses just to confirm this though. I can't see the DC/DC Voltage converter referred to in previous articles either, so looks like an improved amp.

It appears the strip of fuses from 154-159 seem to be iDrive Remote on/off from an internal relay in the fuse block, but want to do some probing to confirm this.

If I can find the correct spade connector for the fuse box, it could make for a very neat, no wire tapping hookup of the remote on/off wire for the LC2i and Sub amplifier.

[949]

nice write up!

i have questions about the LC2i.
the description for this unit states that it will turn on/off using a sensing method on the speaker line.
so why would an extra remote wire be needed?
would this lc2i also be able to remotely turn any other unit like amps on or off too?

[jgentry]

Technic could probably provide a better answer but apparently the high-powered HK system's speaker outputs will not work with the LC2i's level-sensing on/off mechanism. I thought I may have read that somewhere on this forum but I did a ton of research before doing the install so I can't point you to exactly where I found it.

[Technic]

Originally Posted by 949

nice write up!

i have questions about the LC2i.
the description for this unit states that it will turn on/off using a sensing method on the speaker line.
so why would an extra remote wire be needed?
would this lc2i also be able to remotely turn any other unit like amps on or off too?

The HK OEM amp -and any Class D amp- does not have the DC offset at the signal output to trigger most known signal sensing circuits.

The LC2i will not trigger a remote output because of that.

[949]

hey technic,
i was wondering why you choose the LC2i vs other high end loc's?
or is this the highest end loc available?

[Technic]

Originally Posted by 949

hey technic,
i was wondering why you choose the LC2i vs other high end loc's?
or is this the highest end loc available?

The HK OEM amp outputs about 125W per woofer channel, or ~30V peaks. The LC2i can handle up to 400W and -most importantly- 40V peaks.

Most common LOCs will burn with the F30 HK system.

[949]

will your harness also apply towards another second amp for the mid's and tweeters in the car besides the sub amps?
in case someone wants to amplify the speakers inside the cabin.

[Technic]

Originally Posted by 949

will your harness also apply towards another second amp for the mid's and tweeters in the car besides the sub amps?
in case someone wants to amplify the speakers inside the cabin.

Harness will have to be cut and additional LOC required.

[949]

i assume it can be ordered through you with those cut and extra harnesses added when ordering?

[Technic]

Originally Posted by 949

i assume it can be ordered through you with those cut and extra harnesses added when ordering?

I do not support any HK upgrades other than adding a sub/up-powering the underseat woofers. Any other upgrade is much more complex than just adding another amp to the speakers because of the DIRAC processing/built-in EQ curve.

The woofer outputs processing is manageable without the need of any external DSP.

[949]

does your harness jump in between the stock amp and head unit or after the amp to the stock speakers?

[Technic]

Originally Posted by 949

does your harness jump in between the stock amp and head unit or after the amp to the stock speakers?

Photos of the install are posted in very first post of this thread.

[949]

i actually cant tell with those pics. the pics shows where the location is to install your harness, but weather the stock amp is severed from the whole new line, i cant tell nor can i tell if its between head unit to amp, or amp to speakers.