XCarLink MP3 with Bluetooth and handsfree calling install

Hi,

I thought I would share the details of the XCarLink installation I performed in my A2 last week.

The purpose was to upgrade my existing Audi Concert 1 with CD Changer and Bose system to add phone handsfree calling and the ability to play music from memory cards.

Although a number of Bluetooth wireless streaming solutions exist (including the one I chose), I wanted the system to be able to play music without relying on any other device. This should also future proof the system and ensure that I get good quality audio as the standard Bluetooth streaming protocols still compress the data too much in my opinion.

I chose the XCarLink Audi USB/SD MP3 Interface Model V. This provides an analog audio input jack, SD card slot and USB memory stick socket. The later two can be used to place music files.
Added to that was the optional Bluetooth module with microphone. I also purchased a mono 3.5mm jack extension lead for the microphone:

http://www.xcarlink.co.uk/product.php?productid=11&cat=4&page=1

Parts:



The XCarLink module comes with a pre-made loom for the Audi head unit and a short adapter to allow it to be connected in-line between an existing external CD Changer and the head unit. The unit connects to the head unit's CD changer port so that it can feed audio in at full quality using the CD's line inputs and therefore fully utilise the car's sound system. As I have Bose, this is important as some other audio upgrade units bypass the car's sound system completely and drive the speakers directly which would cut out the Bose amplifier and therefore not give the best sound quality.
The existing CD changer can still be used and it is possible to toggle between the CD changer and the XCarLink using the head unit's "Mode" button.

The first task was to sort out the aftermath of a previous owner's installation and removal of a phone hands free kit. This had connected to the head unit and also directly to the driver's door speaker (which might explain why this speaker is damaged).

The speaker wires had been re-joined to connect the speaker back to the amplifier and the joints insulated with "electrical insulation tape". This was done some time ago and the glue on the tape had gone off and the tape had literally fallen off leaving the wires exposed! From my experience I would not recommend using "electrical insulation tape" to insulate connections, but rather heat shrink sleeving or self amalgamating tape.



The connections were properly insulated and the loom rebound.

The other remaining wires were removed from the head unit:



The next task was to route the cable from the microphone used for hands free calling. The Audi factory hands free installation fits the microphone into the interior light cluster at the front of the car. The small rectangular grill on one side is for the microphone, and on the other side is there to make it look symmetrical.

With the light removed, a metal rod was inserted (with suitable protection on the end) from the opening across behind the driver's sun visor to the edge of the roof lining in front of the driver's grab handle:



The microphone cable was protected before installation by wrapping loom tape round. The metal rod allowed the microphone and cable to be pulled back from the edge of the roof lining to the light cluster opening.
The Audi microphone is contained in a rectangular package which clips behind the grill. When not fitted, in its place is a rectangular foam blank. This blank was removed and cut in half and re-inserted. The XCarLink microphone which is cylindrical is then inserted between the two pieces where the foam was cut so that the end of the microphone is facing the grill. This is further secured with additional tape:

The microphone cable was now routed down the A pillar by the windscreen on the driver's side to enter the under dash area. The A pillar trim is in my opinion the most difficult part of the A2 interior to remove! The clips do not fully release until the trim is pulled upwards (and out of the dash). The trim cannot be pulled upwards out of the dash easily until the clips are removed - catch 22.



The microphone cable must cross over from the outer side of the car to the centre and so pass the area with the pedals and steering column. The normal cable routing for this is inaccessible with the dash installed and the area under the steering column with the pedals has many moving parts which should be avoided. I chose to use the area behind the instruments to route the cables. There is plenty of space behind the instrument cluster and there are already cables going up there from both sides. As there are also many sharp metal edges in this area I used a cable routing correlated pipe to protect the cables. The size chosen was just large enough to allow the microphone's jack plug to pass through.



The end of the tube above the fuse box. The microphone cable can be seen going across to the bottom corner of the windscreen. It was taped to the existing wiring loom in that area for support. (The wire seen hanging down was the cruise control power feed routed through the same tube but not yet fitted or connected at the fuse box)



The left side of the tube ends at the centre console area and the cable is routed with the other wiring behind the head unit and climate controls down to the ashtray area. It was then taken across and down by gear leaver. The cable ends there, half way down the front:



The XCarLink Bluetooth module which is the part which contains the wireless transceiver, contains two status indicator lights and a button which can be used to answer / terminate calls and also as a pause / play control for Bluetooth streamed music. The call answer / terminate function can also be achieved by pressing the "FF" button on the head unit so the module could be hidden away. In another installation I did for a friend a couple of years ago I hid the module behind the A pillar trim where there is lots of free space. That was also as far as the microphone cable went, the microphone now supplied with the XCarLink has a much longer cable.

I had decided to place the Bluetooth unit in an easily accessible position which was the space to the rear of the switch panel containing the "ASR" button.
As the module is quite deep, I embedded it into the top edge of the trim piece. To do this, I separated the top and bottom halves of the case and carefully cut the sides off the top half to just leave the upper face. I then cut a hole in the trim to match the circuit board so the case's top can then be dropped on top and the circuit board fitted from below. The top of the case is attached using hot glue from the underside:



This provides an almost flush and neat installation. I had considered "embedding" a cut down top piece totally flush with the trim but didn't think I could cut the two edges accurately enough to be neat.

To fit the rest of the module into the trim I cut the audio jack extension lead and used the part with the socket to connect to the end of the microphone cable. I soldered the wires directly to the microphone socket's tags on the PCB as the positioning of the board made it not possible to insert a plug into the socket. Using the extension in this way allows the module to still be disconnected.

The lower half of the Bluetooth module fits unmodified:



and the cables zip-tied to the trim:



The trim can then be re-attached and the microphone plugged in. The data cable from the Bluetooth module is routed up with the microphone cable into the area behind the head unit and climate controls.



The Bluetooth data cable needs to plug into the side of the main XCarLink unit together with the cable from the head unit so this is routed up inside the centre console and joins with the head unit connection loom as it exits into the area above the glove box where the climate blower fan resides.

I wanted the main XCarLink unit to be accessible but out of the way so I decided to fit it into the glove box. As the glove box interior is quite small, I initially considered mounting it on the top, outside and having a cut out to access the ports from inside the glove box. In the end, I opted for a less destructive but still space efficient solution where by the unit is mounted horizontally in place of the clip on coin holder. This part of the glove box cannot be used for storage (other than coins) so the effective space isn't reduced and the unit is still easily accessible. Note however that for cars with the optional key deactivation of the passenger airbag, this is where the key switch would be located.

Two small holes were cut into the side of the glove box to allow the connectors to pass though and the XCarLink was fixed in place by hot-gluing the side clip on plastic strips to the glovebox.

Positioning of the box is important to ensure that the ends of the connectors do not protrude too far beyond the outer side of the glove box and foul the centre console during fitting. Enough slack was left on the connection cables to enable the glove box to be dropped down and the plugs disconnected from the XCarLink should the glove box need to be removed from the car.

The fitment in the glove box looks like this:



and the centre console with Bluetooth unit like this:

In use:

Phone call quality is very good with both ends of the conversation coming through clearly for all parties.

Playback of MP3 files now shows up the limitations of the low bitrate I had chosen way back when my phone had a maximum storage capacity of 512MB. On high bit rate encoded files, the sound quality is good.

The music playback facility mimics a CD changer so presents 6 "CD"s to the head unit. Each "CD" can have many tracks however, although the head unit only has 2 digits for the track number display so limiting this to 99 tracks per "CD" would stop confusion. The Concert 1 (and 2) cannot display track names so only the number is shown. SD Cards can be easily changed and I have been using 32GB capacity cars without issue (SanDisk 32GB SDHC).

One problem I have however is the brightness of the blue LED in the Bluetooth unit. As I discovered when I fitted the same in my TT earlier in the year, the blue LED is eye-wateringly, blindingly bright, even at day time. Luckily in the TT it is obscured by the steering wheel and wiper stalk as its next to the light switch. In the A2 install I tried to solve this by placing 12 layers of masking tape over the LED during fitting. During daytime use and twilight its fine, but it is still too bright for full darkness at night as I found on my way to the hotel for ADI last Friday. I will probably modify the underside of the button on the Bluetooth unit to block some more light.

regards

Andrew

Hi Andrew,

A very thorough write-up. Excellent as usual.

In times gone by, the XCarLink Bluetooth add-on dongle only allowed hands-free calling, not A2DP music streaming. From what I've read on their website, the dongle now supports A2DP. Do you know whether it now also supports wireless control via the AVRCP protocol, or is that reserved for their Bluetooth-only interface?

Cheers,

Tom

timmus said:

Hi Andrew,

A very thorough write-up. Excellent as usual.

In times gone by, the XCarLink Bluetooth add-on dongle only allowed hands-free calling, not A2DP music streaming. From what I've read on their website, the dongle now supports A2DP. Do you know whether it now also supports wireless control via the AVRCP protocol, or is that reserved for their Bluetooth-only interface?

Cheers,

Tom

Click to expand...

Hi Tom,

the button on the Bluetooth module toggles between play and pause on the external steaming device so there is certainly basic control. The specification of the new streaming only XCarLink module does talk about steering wheel control over track selection etc. but this one doesn't. I haven't tried it yet as my streaming test was only a brief one but I will give it a go when I have put my car back together (*). I will also check out the audio quality with higher bitrate files on the phone but my initial test sounded a bit "under water" and noticeably worse than playing the same files off the memory card.

(*) I have been suffering from various odd dash warnings but I have now I think tracked down the problems. I had damaged the "left hand headlight loom" on its way though the firewall and corroded pins on the A pillar connectors were causing various spurious dash warnings after I had removed and re-inserted the connectors. Lessons learned...

regards

Andrew

Additional note on earthing:

The XCarLink loom has a single wire which does not connect to the head unit and CD Changer, an earth (negative) connection.

For this I chose to provide it with a good solid earth by running a wire to the XCarLink loom connection at the head unit from the passenger side A pillar chassis earth point.

I could have connected it to one of the earth connections on the head unit wiring itself but wanted to provide a good earth as I have been having grounding problems resulting in audio interference. Occasionally, the sound in the car is like the engine has been fitted with a massive supercharger. Unfortunately its only interference from the engine ignition and the car doesn't actually go any faster. This may be a result of the previous fitment of the now removed hands free kit and moving the head unit usually resolved it. This in it self is another artefact of that work as both retaining clips have been completely broken off the radio.

The XCarLink loom has two wires which the instructions suggest should be connected together if you hear interference in the audio. I believe this is for the audio signal earth. I connected this as a matter of cause and since filling the XCarLink I have not experienced any audio interference at all.