Installing my new Stereo


The factory stereo is pretty ok. The car has a BOSE system with amp and 8 loudspeakers. It is equipped with hands-free calling, CD and bluetooth.


All in all, I paid 480€ for everything. Not exactly a steal, but you get what you pay for (at least I thought - silly me).

Most important to me was Apple Carplay + a decent Display, I'm not interested in improving the audio performance at the moment. Otherwise I would have ripped out everything, and replaced the BOSE stuff with off-the-shelf ALPINE or whatever loudspeakers. Equipment that doesn't heavily rely on DSP as BOSE does.


The first thing I ordered at EBay was a used AUX-In-Port. My plan: The USB cable should go through the original aux port into the center console, where the iPhone should be placed later. Carplay runs on the radio via cable.

Therefore I disassembled the AUX port of EBay and assembled the case. So I can put the original part back in if necessary (sale, radio change, vulture knows...).

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Tearing apart the car

This was kind of annoying. To install a stereo into the Mazda 6, you have to tear apart the whole center console. After I was done, it looked like hell:

OPNsense Dashboard

However, the test fitting proved to be promising:

OPNsense Dashboard

A dream collapses

The first test let to a ton of disappointment. There was a hissing sound, and the right side was louder than the left. The removal of the fairings and the preparations at the wiring harness for the radio had already taken 4 hours, accordingly I was pissed off. The wiring harness came with an adapter for the BOSE system. Without the adapter the channels were equally loud, but the noise was even more extreme.

I didn't feel like it anymore, so I left everything as it was, took the stereo and the cable harness upstairs and had a coke. A cold one.

With something like that it starts rattling in my head. Actually I know a bit about electronics - car audio is new territory for me, though, but in the end the cables are made of metal and 12V is 12V.

The included adapter looked like this:

OPNsense Dashboard

I thought about what I was going to do for a while - actually I wanted to write to the salesman and point out to him that the stuff is noisy and somehow not so cool. The CANBUS set in bundle with the adapter cost a good 90€. Looking at the CANBUS box, I guess that a large part of the purchase price was spent for the official approval.

Nevertheless the desire was greater to expose the hardware under the huge heat shrink tube. So what the heck, I cut everything open. That was the result:

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In short: The idea is good, but the hardware screams "cheap!". The electrolytic capacitors are from "Jackcon" (cheap and bad!), and the resistors are normal SMD china stuff.

However, and here it gets interesting: Actually the circuit is a normal voltage divider. No magic is done here.

The reasoning behind it is clear: The BOSE amp doesn't need any pre-amplified signals, but many ISO radios only deliver these. Therefore the voltage is reduced. However, my radio has the appropriate pre-out for an external amplifier. I don't need the voltage divider gaff.

I thought about it for a moment, and then soldered an adapter from Chinch to ISO together. Unfortunately I have no picture of it. Just imagine an 8-pin iso jack with 4 cinch cables. :D

Next thing you know, everything is plugged together again, switched on, and - tadaa! The noise was gone. Completely.

Building everything back together

I reinstalled the trim, and this is how it looks now:

OPNsense Dashboard

And this is what the USB cable in the centre console looks like. Sure, it won't win me the Red Dot Design Award, but it works.

OPNsense Dashboard

(the white one next to it is the 4G stick for WIFI and cellular in the car)

CANBUS & Hiccups

The CANBUS adapter box now only shows "MAZDA" on the screen. This was to be expected. Nice is however that I have access to the "HS-CAN" and "MS-CAN" via the radio connector. I'm thinking about programming something for myself, so that I can use the display for information. Let's see, the possibilities are great now anyway. :D

Anyway, I know now that I would never spend 90€ for such an adapter again. You can find the schematic in the net, the 24-pin Mazda adapters are available for cheap at the store around the corner (Aliexpress), and if you know something about embedded systems, you could solder a much more powerful CANBUS adapter yourself.

Speaking of CANBUS:

During the last start the DSC suddenly blinked and the "skid control light" was on. Some time ago I invested a little bit of money and ordered an OBDLink EX for a handful of dollars (39 or so?) at Amazon.com, because it was not available in Germany at that time.

I plugged it in, started FORScan, and read the error code. Because of my repeated "ignition on, ignition off", the ABS control unit had to reinitialize the steering wheel sensor. FORScan suggested the right way to do this: First ignition on (running engine), then steering wheel fully to the left and then fully to the right, and the error was gone immediately.

Next up: The rear view camera.

It remains exciting. :)