At last the first part of the CarPlay and Audio install is finished and the car finally put back together again!
The last job remaining on the MMI CarPlay box was to find a place to mount the external mic (since I chose not to connect it to the car's original mic). I managed to fix it using double sided tape in a very discreet place next to the engine start button from most angles it can't be seen and it functions well in this position:
For the audio upgrade I chose to use an AudioControl LC6i LOC to give a quality low level line output signal to the 4 channel JBL amp. To get this to work I made a T harness out of the T Harness for the MMI box this way the car's factory loom stays intact. I used this wiring diagram to work out the speaker wires from the factory loom / radio:
I then located the same wires in the CarPlay box T Harness, annoyingly the MMI box factory used the same colour wires for all the speakers meaning I had to cut and label each wire separately. I used insulated bullet terminals which if for any reason I want to bypass the JBL amp I can connect them back up without any problems. I used insulated terminals but the insulation adds a fair bit of bulk and space behind the radio is tight so I sliced the insulation off with a Dremel and used heat shrink instead:
I then made up a new loom to connect to the speakers wires coming from the radio (right side of the loom in the photo above) which would feed into the input of the LC6i and the speakers wires from the amp output connects to the part of the harness going back to the factory wiring, i.e. going to the speakers (left side of loom in the photo). From there the RCA cables from the LC6i would provide a low level signal to the amp.
I fixed the LC6i using very strong double sided tape to the top of the glove box and screwed the glove box back into place:
When putting all the trim back I ran into a slight problem with the upper right rear side trim, since I hadn't removed this entirely due to the seat belt bolt I couldn't properly seat it in the lower rear side trim and as a result the bottom of the upper trim sticks out a bit. The only way to fit it properly is to remove that seat belt bolt since the upper trim needs to slide in from the top into the lower panel. Oh well something to sort out when I get around to mounting the subs in the panel behind the seats.
In the boot I put all the trim back and left a set of RCAs and remote turn on wire on the floor of the boot ready for the second amp for the subs. Something I will tackle in the next month or two.
As mentioned earlier I am really chuffed with the end result. The difference really is night day compared to the stock 6 speaker system.
The total spend so far:
Crunch DSX42 rear coax speakers 36€
Crunch DSX4.2C component speakers for the doors 59€
Hertz MP165.3 6.5" woofers for kick panels 102€
AudioControl LC6i (purchased second hand) £50
JBL Stage A9004 4 channel amp 120€
RCA / Speaker Cables and misc. 70€
2 x Kicker Comprt 6.75" Subs (not yet fitted) 98€ each
Apple CarPlay / Android Auto MMI box $160
Still left to purchase, an amp for the subs.