Adding a Sub Amp to the Factory Amp
Contributed by: alpac
How to add a subwoofer amp to the X5 factory audio
The bass is used to convey power & force and to give the listener the fullness and depth necessary to really enjoy the music.
When I bought my X5 the very first thing I noticed was that, although the audio components were of pretty high quality, there was a definite lack of lower bass. The audio system can be easily improved by adding a subwoofer and a sub amp.
In this document I explain how to connect a sub amp to the X5 stock amplifier equipped either with DSP or non DSP.
I have described 3 different connector types that I have seen on X5ís stock amplifiers and explain where to get the sub signal for each of them. This is to connect a subwoofer amplifier equipped with high level (speaker level) inputs. High level inputs enable tapping into the speaker wires to feed a subwoofer amp. It is called high level because the signal has already been amplified as opposed to a low level signal (pre-amp level) which needs to be amplified before going to a speaker. If your amp only has low level inputs and you want to connect it as explained here you will need to add a line level adaptor before feeding the subwoofer amp.
Connections to the factory wires are made using crimp & snap connectors like the one shown in the picture below.
Powering the sub amp
In addition to feeding your subwoofer amp with the appropriate sub signal input, the subwoofer amp will need to be powered by a constant (+12v) direct from the battery, a good ground and a (+12v) remote 'turn-on'.
You can get a good constant (+12V) from the power and ground point. The power and ground point is a plastic box (usually green) located near the spare tire under the trunk floor. You should find several Ďemptyí power taps that you can use to power your sub amp. Each available power tap has enough current capacity to power your sub amp and is protected by a fuse.
Picture 2 shows the (+12v) remote 'turn-on' source connector where I got the remote on/off +12v. I found the connector (shown on the picture) somewhere under the CD changer. I tested all the wires with a voltmeter and found one which worked with the ignition. Not sure if you will have a similar connector in yours. Use a voltmeter to check which of the wires is a +12v connected to the ignition. To prevent any damage you should always use a voltmeter and ohmmeter to double check all wirings before making the connections.
Identifying the type of connector
The very first thing to do is to identify which type of connector you have on your factory amp. To examine the connector remove the flashing (usually on the left side of the cargo area). The CD changer (if equipped) and factory amp are located in the lower part of the mounting brackets, found behind the flashing. If your car is equipped with the CD changer you will have to remove it to have full access to the factory amp connector. To look at the connector you must eject it from the amp. This is done by sliding the connector with the help of a tool such as a screwdriver for example. Picture 3 below shows my X5 factory DSP amp, cd changer and the added sub amp.
Type of Connectors
1) if you have an X5 with premium sounds and DSP: You should be able to count 15 pins in this connector even if all pins are not wired. On this connector you can tap into pin # 7 and 14 to feed your high level (Speaker level) subwoofer amp inputs. You should notice 2 cables thicker than the others. These are pin #8 (power +12v) and pin #15 (ground). That should help locate pin #7 and pin #14.
Picture 4 below shows the 15 pins connector on my X5 with 2 red snap connectors connected to pins# 7 and 14 and two added wires (blue and white) which go to my subwoofer mono amp high level input. If you have a 2 channels amp instead of a mono amp then verify that it is bridgeable which means that you can bridge the 2 channels into one to feed a subwoofer. Not all amps are bridgeable. This should be clearly specified in the documentation of the amplifier. Also be aware that by bridging there will be twice the power on one speaker. The bridged rating is usually listed with the spec of the amp. If you have a 2 channel amp you can feed your ampís high inputs from pin # 7(-)/14(+) for right speaker and 10(-)/2(+) for left speaker. I only used 7/14 in my case because I used a mono channel amp
2) X5 non premium (no DSP): You should see 12 pins in this connector even if all pins are not wired. Picture 5 below shows the wiring of this connector. You can tap into pin # 5 and 6 or 11 and 12 to feed the high level (speaker level) inputs of your subwoofer amp. As explained in the previous section if you have a 2 channel bridgeable sub amp you will be able to feed your ampís high inputs from pin# 6(-)/5(+) for right speaker and 12(-) /11(+) for left speaker.
3) Other Harman/Kardon equipped X5: After ejecting the connector you should now see 2 connectors side by side, a gray one and a black one. The pins are numbered from 1 to 13 on the gray connector and from 22 to 34 on the black one. The pictures 6 and 7 below show the 2 connectors. On this connector Pin #1 (-) and #2 (+) are for left rear woofer and pin #24 (-) and #25 (+) are for right rear woofer.
Picture 6 - provided by btrvalik
Picture 7 - provided by btrvalik
You can tap into #24 and #25 to feed the high level inputs of your subwoofer amp as shown in the picture 8 below.
If you have a 2 channels bridgeable sub amp you will be able to feed your ampís high inputs from pin# 24(-)/25(+) for right speaker and 1(-) /2(+) for left speaker.