BMW F10 Premium / Professional Audio system - adding a sub woofer part two I accept no liability for any work carried out as a result of this guide. Any damage caused to equipment or your car (or you) is nothing to do with me! Part one of this two part document was intended to provide an insight and reference into the F10's audio system and the kinds of connectivity available for aftermarket amplification. This instalment is intended to show how an additional amplifier and subwoofer upgrade can be physically implemented including how to remove the various interior components and where electrical connections can be made. The guide assumes a boxed subwoofer will be used since I needed the ability in increase boot (trunk) space to transport things as and when necessary. The details show how to install the amplifier on the parcel shelf. This seems to be the only hidden location where the amplifier can realistically be installed. If you weren't concerned about the amplifier being hidden and you had fixed rear seats, you could acceptably mount the amplifier behind the rear seats. Parts needed In order to carry out the upgrade you will need the following:- Amplifier The chosen amplifier should ideally accept 4Volt line level signals and have sufficient power to drive your subwoofer(s) of choice. The F10 is a large vehicle, so powerful speakers are needed to provide sufficient throw. The exact specification is predominately down to the end user and what they want to achieve. My initial test setup will utilise a 10" boxed subwoofer, however I intend to use 2x 12" subwoofers when I get around to buying them. The amplifier I'll be using is a JL audio XD400/4. This is actually a 4 channel amp, but it can also be used in two channel bridged mode to provide 2x200Watts RMS into 4 Ohms. If I was buying a new amplifier, I'd probably go for the XD600/1, however I already had the XD400/4 and it's a perfectly good device so want to use it. JL Audio XD 400/4 Speakers The speakers should be suited to the chosen amplifier. The speaker / box setup I will probably end up using is the JL Audio JL-CP212-W0v2. This is a 2x12" solution with purpose designed box. The speakers are wired in parallel inside the box bringing the overall impedance down to 2 Ohms. If I get this I'll need to re-wire it to give me 2x 4 Ohm loads for use with my XD400/4. If I had the XD 600/1 no re-wiring would be necessary since that amplifier can handle one 2 Ohm load. JL Audio JL-CP212-W0v2 Page 1 of 15
Line Driver During my testing in part one, I measured 20 Volts peak to peak under load from the subwoofer outputs of the F10's amplifier at around half volume. Further tests showed an output of over 50 Volts peak to peak. This cannot be directly attached to an additional amplifier so a suitable line driver is needed to match the load output of the F10's amplifier to the inputs of the new amplifier. There are various types of line drivers available for this purpose. The two that has been tested thus far are:- FLI Audio line level convertor (FLI-FLLC) Basic transformer based line driver. I confirmed the use of this device with a digital storage oscilloscope and the output did not go higher than 3.8 volts peak to peak. The final output from the JL amplifier also provided a near perfect sine wave under load at 65Hz while outputting 151 Volts peak to peak, so no distortion from the output of the JL when using this device. AudioControl LC2i Active line driver with EQ and bass roll off correction. Testing in part one revealed that the bass from the F10's amplifier rolls off (reduces) at 58Hz. This device has an automatic gain compensation circuit that as closely as possible creates a flat response below 58Hz by increasing the gain where the roll off occurs. If you're after REALLY low bass, then this device is for you. Thanks to Bimmerfest.com forum member Glock 32 for suggesting this option! I'm actually quite happy with the default output from the FLI line driver, but if you're spending serious cash on your amplifier and sub you should probably use one of these things. Another similar device that could be considered would be the Rockford Fossgate 3SIXTY interactive signal processor, however I have not tested it in the F10. Page 2 of 15
Power Cables You need to use power cables that are adequate for the current requirements of your amplifier. AWG8 wire should be used as a minimum. I opted to use AWG4 since this will give me the flexibility to install a larger amplifier at a later date if I so wish. AWG4 is hefty stuff! Other stuff Thin wire, heat shrink tubing, solder, soldering iron (NOT scotch locks or crimps), harness cloth, fuse and holder suitable for the power cable. Where to start Now you have all your gear together we can start to take apart the interior of the vehicle. My car has split folding rear seats, so I'm unable to give exact directions for cars that have fixed seats. If anyone can provide further details please do! First thing is to remove the rear door rubber on both sides of the car where it meets the quarter panel trim. You only need to remove enough rubber to expose the edge or the quarter panel trim on both sides. Next, remove the plastic 'Airbag clips from the quarter panel trim on both sides. A plastic spade should ideally be used for this to prevent damaging the plastic parts. If you don't have one, you could use a small screwdriver if you take care. Page 3 of 15
Under the Airbag plastic clips are Torx screws. Remove those. With the seats folded down, Pull the seat pillars off on each side by exerting force with your hand as shown. When the pillars come off, the retainer clip will still be attached to the car. Remove the retainer clips on both sides by pushing the inner clip down and withdrawing forward. Now re-attached the pillar clips to the reverse of the pillars as shown ready for re-assembly later. Now remove the quarter panel trims by pulling them away from the car. Unfortunately I didn't take a photo of this, but they are held in with white plastic clips. The clips may come detached from the quarter trims, however they can be prised from the car and slotted back onto the trim panels easily enough. Page 4 of 15
Many of the interior trim parts are held in using black plastic clips which come in two parts. To remove these clips you should remove the centre male part with a screwdriver, then the outer female part. The clips look like this:- next remove the parcel shelf. It is held in with several of the 'black clips' behind where the seats fold down. Before you pull the parcel shelf out all the way, pull it forward slightly, then while lying down on your back - unplug the connectors for the parcel shelf speakers. Page 5 of 15
Once the speakers are disconnected, the shelf will come out still attached to the seat belts. Next we need to remove the floor in the boot (trunk). Lift the flap to reveal the storage compartment. Either side are two 10mm plastic nuts. Take these out. The whole floor liner will now just lift out to reveal the battery. Now remove the panel from the inside of the boot (trunk) and pull the rubber seal off on 3 sides leaving it attached at the top. The photo below shows from inside the boot, but the removal should be done from outside of the car. The plastic clips retaining the panel are of a different size to those used elsewhere in the car, so keep them separate. Page 6 of 15
The Storage compartment should now just lift out fully revealing the battery. Next we need to remove the two side panels from inside the boot (trunk). They too are secured using black plastic clips as the same type as the parcel shelf. There are also two large Torx screws that need to be removed holding in the luggage strap eyes. When all the clips and Torx screws are out (including the ones under the parcel shelf and behind the seats) you need to carefully prise the panels from around the boot lid struts. Page 7 of 15
We should now be stripped and can crack on! Let's get a good Ground connection for the amplifier. I found a nice Torx screw holding a ground wire already in the quarter. With a soldered lug, I attached my AWG4 black ground wire to it. Next for the power line. Most important thing here is that it should go straight to the battery, but **MUST** have an inline fuse. Did I mention that the power wire ***MUST*** have an inline fuse? Put it this way - if you don't have a properly installed inline fuse and the power line gets snagged on the chassis of the car, you WILL end up with a serious fire that will ignite extremely quickly. Can't say I didn't warn you! Make sure the fuse is as close to the battery as possible. I found an unused threaded post sticking out just behind the battery. My fuse is 40A which is more than enough for my amplifier. The AWG4 wire means it can withstand considerably more than 40A, so is safe. Page 8 of 15
Next, run the power line to the amp. I went behind the boot (trunk) back panel, behind the antenna amplifier (next to the OEM amp) and behind the Combox up through the hole where the sunroof duct goes. Make sure the power line is attached to the amp *BEFORE* connecting to the battery. I used cloth harness tape to secure all cabling. The power line attaches to the battery really easily. There is a plastic flap that lifts off exposing a 13mm nut. Take off the nut and 'try' to keep the existing power line connected while attaching the new lug, otherwise some of the electronics on the car will reset their settings to factory default. This doesn't cause a problem, but is a pain to have to set everything up again the way you like it (no idea how I know that...). Page 9 of 15
I'm using the FLI line driver, so need to extend the wires. Best way to do this is to twist them together, solder and heat shrink. Next, we need to make a harness to include the output speaker wires from the new amp and the remote turn on wire. I ran these over the parcel shelf on the other side of the car and through the harness box to near where the fuse box is in the boot (trunk). Again, the cloth harness tape came in handy. I wanted the ability to adjust the output level from inside the boot (trunk), so purchased the optional remote level control for use with the XD400/4. Mounted this in a pre-existing hole in the shelf. Page 10 of 15
Fully wired amplifier looks like this:- Now to wire up the outputs from the OEM amp. Rather than tap directly at the amplifier, I made the connections within the harness box that is on the same side of the car as the OEM amp that hides behind one of the boot (trunk) panels. The only photo I have of this is before I soldered / taped and harness taped them. Thick blue wires are right, while thick black wires are left. Red stripe is +, Brown stripe is -. Notice how I spaced where the insulation was stripped and I didn't actually cut the wires. This is best practice and minimises the chance of a short circuit if the insulation tape is breached. I prefer to tape these kind of connections rather than cut / heat shrink. Ignore my oscilloscope probe! Page 11 of 15
Getting there at last! And this is the line driver in situ before it was mounted:- Next we need to mount some binding posts on the right hand panel for the speaker outs to our subs. Posts mounted Posts connected The above photo of the posts shows no heat shrink. I took them off and did them again, this time with heat shrink, but forgot to take a photo. Heat shrink minimises the possibility of a short. Also, Page 12 of 15
you need to make sure that there is no chance the posts could come into contact with the lid spring or chassis of the car when in situ, otherwise your amplifier will get very upset! I didn't take a photo of where I connected the remote turn on wire, but there are numerous places in the rear fuse box that are only on with the ignition. You need to use a multi meter to determine a suitable point. The fuse box is mounted with 3x 8mm nuts (I think!). You should make the connection on the secondary side of a low value fuse, or ideally mount an inline fuse as close as possible to the fuse box. Below shows the right hand side of the car harnessed up before I replaced the covers. Note the green remote turn on wire coming from the bottom of the fuse box. As good as BMW's harnessing :) Setting up There are different methods for setting up, however I prefer to set things up by ear as much as possible. I also have the benefit of my oscilloscope just in case I can't hear the distortion for some reason. This sometimes goes against the manufacturers recommendations, however I feel I get better results this way. The JL audio manual gives plenty of detail on the preferred process, however my gain on the XD400/4 is set half way and the frequency is set to 11:30. filter is set to LPF, although you could try setting to full range since the F10 already employs electronic crossovers. My setup has four connections for the speakers to account for the two bridged channels, however if you are using a mono amp, you will only need two connections. Distortion should be avoided at all costs. Distortion occurs when the waveform deforms and enters a square wave shape. This is progressively similar to connecting your car battery directly to your speakers (only to a lesser degree), but the net result is that it will burn out your voice coils overtime. Page 13 of 15
Finished install The is my level control from under the parcel shelf. Binding posts mounted and installed. My test sub box in the car (need a better one!) Page 14 of 15
Please don't shoot me down for grammar! I've done this really quickly as time is an issue at the moment. Hope the guides are of use and look forward to hearing your experiences! BimmerUKF10. Page 15 of 15