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oztme 05-11-2022 04:53 AM

Tap into Head unit to get raw Audio bit stream?
 
1 Attachment(s)
Hi,

I have an X3 with a terrible stereo. No tweeters. Very ordinary.

I want to pop the lid on the CIC (NBT/EVO?) and on the circuit board, find a test point, or somewhere I can tap into to get a raw bit stream, prior to any amps/crossover inside the head unit (note I do not have the BMW amp in the back that the hifi/top hifi options include)..

I am an electronics nerd. Can design circuits, design multilayer circuit boards, have SMD and reflow equipment, microscope etc.

Has anyone done this before? The UI is great, the Android Auto works great. I just need to get that bitstream....

For example, in the attached picture, I want to find the points inside the head unit where the signals are as shown by red dots in picture...

Cheers + thanks,
Scott.

RocketyMan 05-11-2022 06:07 PM

You want wire colors, locations, and what-not going from the pre-amp to the amp? Easy...

RocketyMan 05-11-2022 06:14 PM

S677 HiFi System Professional DSP
 
A18 Amplifier
Plug connector overview
Number X-pin, colour Description
X10266 42-pin, Plug connector Amplifier

Pin assignments at plug connector X10266
Pin Type Description /Signal type Connection /Measuring notes
1 A Signal, speaker - Subwoofer, front left
2 A Signal, speaker + Subwoofer, front left
3 A Signal, speaker - Tweeter, rear left
4 A Signal, speaker + Tweeter, rear left
5 E Terminal 30 Fuse F81
6 -- Not used
7 -- Not used
8 -- Not used
9 E Signal, AF radio, front right + Radio
10 A Aerial switching signal Aerial diversity
11 A Signal, speaker + Tweeter, front right
12 A Signal, speaker - Tweeter, front right
13 A Signal, speaker + Mind-range speaker, rear right
14 -- Not used
15 -- Not used
16 -- Not used
17 E Signal, AF radio, front right - Radio
18 E/A K-bus signal K-bus connector
19 -- Not used
20 -- Not used
21 A Signal, speaker - Mind-range speaker, rear right
22 A Signal, speaker - Tweeter, rear right
23 A Signal, speaker + Tweeter, rear right
24 A Signal, speaker - Subwoofer, front right
25 A Signal, speaker + Subwoofer, front right
26 M Ground Ground point
27 -- Not used
28 E Mute Telephone
29 E Signal, telephone AF - Telephone
30 E Signal, AF radio, front left - Radio
31 A Signal, speaker + Mid-range speaker, rear left
32 A Signal, speaker - Mid-range speaker, rear left
33 A Signal, speaker + Tweeter, front left
34 A Signal, speaker - Tweeter, front left
35 -- Not used
36 -- Not used
37 E Signal, telephone AF + Telephone
38 E Signal, terminal 50 via vehicle immoblizer Radio
39 A Signal, speaker - Mid-range speaker, front left
40 A Signal, speaker + Mid-range speaker, front left
41 A Signal, speaker - Mid-range speaker, front right
42 A Signal, speaker + Mid-range speaker, front right

RocketyMan 05-11-2022 06:55 PM

S677 HiFi System Professional DSP
 
1 Attachment(s)
Here is the wire colors.

RT = Rot = Red
BR = Brun = Brown
OR = Orange
BL = Blau = Blue
GE = Gelb = Yellow
SW = Swarz = Black
WS = Weiss = White
VI = Violet
GN = Grun = Green

"X/X" -- First [main] color / Striped color

oztme 05-11-2022 07:14 PM

Thanks RocketyMan.

Sadly, my car doesn't have an external amp. This is the very bottom end unit. Even below the base "hi-fi" which is the default in most of the world!

I think because of Australia's bullshit car luxury tax, they stripped out a lot of things to get it down to a price point.

In my cupboard I have an Alpine PXA-H800 processor which will do automatic sound correction (like Audessy) etc. That would be an ideal option.

I'm preferring to get a digital bitstream somewhere to feed the processor stream, rather than head unit converting to analog, through its crossover to it's internal amps out to the speakers, and trying to then take that speaker level signal back through Analog-Digital->processor->Digital-Analog->amp-speakers.

Thanks for the diagrams. I wonder if those outputs to the amp (RadLV+, RadLV- etc) are enabled if you only have the base system, or if you need to have your VO changed/ head unit coded?

I also wonder if they are differential line level signals?

If nobody knows, I can dig out my Oscilloscope on the weekend...
If they are line level signals (differential or not) that would solve my problem I think.. :)


Thanks heaps ..

Cheers
OzTme

oztme 05-25-2022 02:31 AM

3 Attachment(s)
Hi Guys,

Well, finally got around to taking my head unit out. Wow. This was a surprise. This is in an Australian delivered X3, 2019 model, with the base stereo (not even hifi).
The whole setup is different. Gone are the MOST connectors, and a whole bunch of other things..

This is the internal photos (scroll down for pics)

https://fccid.io/T8GMGU/Internal-Pho...ctures-3811252


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