[ot1]

The reason, it appears, is simple: the optical network itself - the physical strands of glass fiber - don't have enough bandwidth to support more than 2 channels of audio.

Here's a clip from Wikipedia:

optical audio cable" or just "optical cable", its most common use is in consumer audio equipment (via a "digital optical" socket), where it carries a digital audio stream from components such as CD and DVD players, DAT recorders, computers, and modern video game consoles, to an AV receiver that can decode two channels of uncompressed lossless PCM audio or compressed 5.1/7.1 surround sound such as Dolby Digital Plus or DTS-HD High Resolution Audio. Unlike HDMI, TOSLINK does not have the bandwidth to carry the lossless versions of Dolby TrueHD, DTS-HD Master Audio, or more than two channels of PCM audio.


So, there ya go.

Now, that still doesn't explain how the Mercedes stereo does it; after all, they were doing 4 channel stereo over the same optical network. But it sorta suggests that there's some crafty signal processing going on. In a stereo image, the left signal is different from the right signal; but the front and rear signals are identical, differing only in their relative volume. So I think that printed into every header on each data packet is a chunk of code which says, in effect: "take whatever the signal is for the front channels and duplicate it at the rear, but make it X percent louder or softer." They don't need to send the same data twice; all they need to do is send the relative volume levels. I think that's how they did it.

A conventional car stereo doesn't generate that data packet; it just cranks out an analog stream on each of the 4 channels. It might - in theory - be possible to create a circuit that would 1) digitize all 4 channels; 2) compare a sample off a front channel to a timestamped identical sample off a back channel, and thereby determine the intended volume of the front and back channels; and 3) recreate a data header and packet that the Harmon Kardon Amp would understand, and slip it into the data stream.

That might work. But the knowledge to create that product is far beyond me; I just dream up the ideas, and let others do the real work.

Peace, all - Charlie

Millions of people can hear upper range sound (maybe not so much older people) of 20KHz or some even better, so let say 22KHz. OK to sample this analog wave and convert it to digital the sample rate must be least twice the highest audible frequency (Nyquist Theorem), 5 channels (left, right,front,back,sub) 5 x 48K = 240Khz, however the Harman Kardon HK Logic 7 is actually 8 channels =384Khz, but this is easily obtained running over fiber which can handle gigabit transmission rates, despite what the Wiki says. So coupling only a left and right analog audio channels from the Android H/U via RCA into the aftermarket MOST adapter is going to throw away 6 channels of superb audio quality. Mercedes isn't using magic to get the sound to the rear HK processor/amp, just state of the art design, haha 2002 I believe.

 

[ot1]

Well, Dave, now you've got me worried.

I've got the Comand unit with the 'sat' button. When I press it, I get a message "sat receiver not installed" (or something along those lines).

I do have an external shark fin antenna just above the rear window.

Now... will that antenna work for GPS even if my COMAND unit doesn't have a GPS installed?

Hey, I know how I can test this. I'll just take a cheap garmin inside, turn it on and see if it can find some satellites. Or my phone, for that matter.

Okay. That will let me test it, to see if I'm going to have a GPS reception issue.

It was always my intention to use the shark fin antenna, but as an AM/FM antenna. Not for GPS.

I know what you mean about family issues. I'm the only driver in my family, and all next week is totally booked - taking my Mom (95 Y.O.!) to the doctor, taking my sisters dog to the vet, taking my Mom to a different doctor... each one seems to eat up a sizable chunk of the day, and of course you cannot really take the dash apart when you also have to use the vehicle. And Sunday is Mothers day...

So, not this coming week. But the week after! That's the time!

Take care, guy - Charlie

The SAT button is for SiriusXM and on a 06 E320 that antenna is not the Sharkfin which is used for NAV GPS and phone, not sure if AM/FM too. The SAT antenna is a bump on the trunk deck lid.

 

[ot1]

The link you gave does not specifically indicate Sirius/XM radio, so I would not think it has it - though I confess, I am not familiar with the unit itself. The ad's wording is confusing , positioning "Satellite" (without "radio") and "GPS next to each other; GPS is of course a satellite based system for navigation, so the unit would seem to have that. Also - perhaps you had already considered this, but a $200 S&H charge is pretty high.

The Mercedes SiriusXM receiver is on the MOST ring, so unless the aftermarket H/U has a built in SAT (SiriusXM) receiver its not going to work.

 

[looksrshady]

Does anyone have a theory as to why im only getting sound from one side of my car?
I connected everything following this thread and all good except im not getting full sound on all speakers. I dont even know where to begin to troubleshoot.

 

[ot1]

@look, did you use an adapter to get into the MOST? Did you check the analog outputs of the Adroid HU using a spare speaker?

 

[looksrshady]

Turns out my right front coax on hu plug was doa, I replaced it and now all good

 

[Asadxtr]

Do I need an optical decoder? MOST audio 20(mf2311)

Hi guys,

I've ordered the aftermarket unit myself too and It's being shipped right now .

But I'm really confused whether I need an MOST optical decoder or not. I've an AUDIO 20 MF2311 unit.
W211: E220cdi (2003)
Searched for the amplifier in the trunk but It wasn't there.

So I think it's the situation shown on Page 49 of this document:
https://web.archive.org/web/2006090...w.mercedestechstore.com/pdfs/416_Telematics/416 HO MOST (CooksonI) 07-01-04.pdf

So I'm thinking that the only thing in the MOST ring/loop is the "Smart cradle control module (UHI)", because there is also no CD Changer installed.

I did a test with my AUDIO 20 with the MOST fiber cable disconnected and the sound was still working.
Does this mean that I can use the aftermarket without the fiber optic cable connected anywhere or would I get issues because of an "open MOST loop/ring" or something? Will I need to buy something or will it be Plug n Play? Kinda confused here

Does anybody know?

 

[Skylaw]

First, please let me congratulate you on doing your research. Your question is asked beautifully. Unfortunately, I am not certain of my answer, because I am not adequately familiar with the Audio 20 system. However, I think you are on the right track. If the only thing you are using on your fiber optic loop is the phone, you will lose that capability - but most replacement HUs have built-in Bluetooth, and you should be able to connect that way.

If I recall correctly, the Audio 20 had its own built-in amp (at least, for the front speakers in some configurations). If your replacement HU has its own amps (with speaker level outputs) you will not have to worry about anything to convert copper wire to fiber. You should be able to go directly to the speakers.

If I am wring here, please chime in!

 

[Asadxtr]

Thank you for your reply and help Skylaw!

I did a lot of research but couldn't find an answer to this . I'm learning as I go here. Really had to replace my Audio 20 HU, it just couldn't do anything!
The audio 20 had:
-No aux input capability programmed or installed
-Cd player stopped working(Tried to fix it, but didn't work)
-No CD changer installed
-No navigation
-Couldn't use the cradle, because who uses a Nokia these days haha
So I was basically stuck with only the radio :grin

I think you're definitely right here.
The audio 20 HU has its own amp. I've searched for Its output power specification, but couldn't find it though.
The Aftermarket HU has also its own amp called: TDA7851L - "4x48W MOSFET quad bridge power amplifier"
Full spec sheet: https://www.st.com/resource/en/datasheet/tda7851l.pdf
High output power capability:
– 4 x 48 W/4 ohm Max.
– 4 x 28 W/4 ohm @ 14.4 V, 1 kHz, 10 %
– 4 x 72 W/2 ohm Max.

I don't know how good it is compared to the Audio 20 amp though. I'll let you guys know when I find out I guess, it will arrive in a couple of days!

 

[MB•David]

The short answer is YES, it will be just plug and play, assuming the new HU is model-specific.

You do not need fibre optic decoder nor MOST loop, etc, etc.

The Audio 20 you have is not NTG1, it's NTG2 - I had the same model (slightly different shape as my car is C169), and I had UHI & CDC, plus power sound system with extra speakers and subwoofer, but no extra amp.

As you know, the UHI and CDC become redundant (or, in your case - just the UHI), but everything else works fine, including subwoofer.

It's been a year now, since I installed the new HU, and it's perfect - not a single issue so far.

Old:

New:

 

[Asadxtr]

The short answer is YES, it will be just plug and play, assuming the new HU is model-specific.

You do not need fibre optic decoder nor MOST loop, etc, etc.

The Audio 20 you have is not NTG1, it's NTG2 - I had the same model (slightly different shape as my car is C169), and I had UHI & CDC, plus power sound system with extra speakers and subwoofer, but no extra amp.

As you know, the UHI and CDC become redundant (or, in your case - just the UHI), but everything else works fine, including subwoofer.

It's been a year now, since I installed the new HU, and it's perfect - not a single issue so far.

Old:

New:

Thank you for your reply MB David!

I thought it was NTG1 because there is no sound amplifier in my E220(2003) and because it's one of the earliest models :dunno: . But I think you're right.
Nice to hear that everything will work fine and that it will be PnP .

By the way your setup looks great! That new HU and carbon fiber trim gave your car a new look! :thumbsup:

 

[Dave2302]

/\ /\ /\ Agreed, your speakers are hard wired at the front, the beige plug on your H/U, which will plug straight in to your new Android H/U :grin

I too got lucky, my W220 was a non Bose Car, so mine plugged right in :grin

Beauty of this is you don't have to go to the (minor) hassle of wiring the Centre Dash and Rear Shelf Woofer Speakers, because they are already connected in your loom, so they will work right off the bat :wink

Bose Cars have separate Amp Channels for these 2, so you have to re hard wire them at the Amplifier Plug

HTH,

Cheers Dave

 

[MB•David]

By the way your setup looks great! That new HU and carbon fiber trim gave your car a new look! :thumbsup:

Thanks! :grin

Yes, the HU works well with carbon fibre, which I 'restricted' to the centre console only, leaving the upper and side trims in original matte "dotted" aluminium, and also the custom steering wheel, gearshift handle and the armrest, all re-trimmed in Mercedes OE perforated leather and (steering wheel) in nappa leather, make the interior feel much more modern, I think.

I few blue LED ambient lights help too :wink - footwells, power socket tray, and the latest ones, which I only recently fitted - the door handle lights.

 

[ot1]

Hi guys,

I've ordered the aftermarket unit myself too and It's being shipped right now .

But I'm really confused whether I need an MOST optical decoder or not. I've an AUDIO 20 MF2311 unit.
W211: E220cdi (2003)
Searched for the amplifier in the trunk but It wasn't there.

So I think it's the situation shown on Page 49 of this document:
https://web.archive.org/web/2006090...w.mercedestechstore.com/pdfs/416_Telematics/416 HO MOST (CooksonI) 07-01-04.pdf

So I'm thinking that the only thing in the MOST ring/loop is the "Smart cradle control module (UHI)", because there is also no CD Changer installed.

I did a test with my AUDIO 20 with the MOST fiber cable disconnected and the sound was still working.
Does this mean that I can use the aftermarket without the fiber optic cable connected anywhere or would I get issues because of an "open MOST loop/ring" or something? Will I need to buy something or will it be Plug n Play? Kinda confused here

Does anybody know?

You can see what is on the MOST ring by accessing the engineering mode on the HU. and its a ring so if a component is removed you have to install an optic jumper and tell Star that item is no longer in the loop.

 

[charlieworton]

So... you might have noticed that I haven't been around the forum lately. (Or maybe not; I do have an elevated sense of my own self importance).

It was a really, really bad summer. In emergency twice. Part of the time, I thought I was gonna die; part of the time, I just wanted to.

So now I'm at home, convalescing... and I thought it would be a good idea to try to upgrade the operating system on my Android 8 head unit. Same one that expbaby has, I think.

So, the instructions on the tin were pretty simple. On the first of two SD cards, use the SD firmware tool to create a boot disk. Then, delete the sdupdate.img file, and replace it with another sdupdate.img file downloaded from a different location, and intended for Android 8 (the sd firmware tool creates a boot image for android 6).

This left me with these files on the SD card (see picture)

rksdfw.tag
sd_boot_config.config
sdupdate.img

So, the instructions said to "Insert the first SD card into the device into the SD card slot. Click on RESET or turn on the device (if it was off). The update will begin. When it is finished, it will ask you to remove the SD card from the SD card slot. Remove the SD card. The unit will reboot and the word "erase" appears. The device will reboot again."

Yeah... no.

I stuck the card in, and powered up the device with my bench power supply. I hooked up the B+ and ACC wires to positive 12 volts, and the black GND wire to ground. I pushed the button...

...and the unit booted up normally. Just as if the card wasn't there.

So I powered the head unit down, removed the card, put it back in my card reader... and the files were changed. Now I had: (see picture

Android (folder)
LOST.DIR (folder)
rksdfw.tag
sd_boot_config.config
sdupdate.img

So, I dunno. I started fritzing with this thing about 3.5 hours ago, and I've just had enough. Admittedly, part of the problem is that the computer in my bedroom only has 4GB of memory, so it tends to get bogged down easily, and fails to load web pages properly. Just that, alone, has me ready to throw lumps of pablum at the wall. I hate a s....l....o....w.... computer.

Anybody help? Could use a little, I think.

>Charlie

 

[503865]

I'm still trying to get to the bottom of all this.

My CLK63 needs (well, the owner I]wants[/I]) a new head unit.

Which, if any, of those Chinese units you see all over eBay is a safe bet?

How about this one?

https://www.ebay.com/itm/For-Merced...splay:6.2L|Make:Mercedes-Benz&hash=item1caadedc17:g:T~4AAOSwXiZbbTJp:rk:12:pf:0

In order of importance I want:

1. Must use all speakers, including the in-dash center and in-door tweeters and the sub using the existing MB amps if possible;
2. Bluetooth interface with microphone for my cellphone (Android);
3. Decent sat-nav, either Garmin or other GPS based, or readily updateable by SD-card or similar;
4. SD-card or micro-SD card slot for playing my MP3s;
5. Back-up camera interface;
6. Works with steering wheel controls and in-dash information panel;
7. Will last longer than the next set of tires.

I guess I will need a MOST adaptor as well.

I've already got a GPS antenna stuffed under the dash from when I was borrowing the head unit out of the wife's now-totaled CLK350. I also have the (hopefully redundant now) CD autochanger in the glovebox and the aux cable socket has been changed to one that takes a standard 3.5 mm stereo plug.

 

[gsxr]

I'm still trying to get to the bottom of all this. My CLK63 needs (well, the owner I]wants[/I]) a new head unit.

Which, if any, of those Chinese units you see all over eBay is a safe bet? In order of importance I want:

1. Must use all speakers, including the in-dash center and in-door tweeters and the sub using the existing MB amps if possible;
2. Bluetooth interface with microphone for my cellphone (Android);
3. Decent sat-nav, either Garmin or other GPS based, or readily updateable by SD-card or similar;
4. SD-card or micro-SD card slot for playing my MP3s;
5. Back-up camera interface;
6. Works with steering wheel controls and in-dash information panel;
7. Will last longer than the next set of tires.

I have the same question, but with a slightly modified list of needs. :grin

1. Must use all speakers, including the in-dash center and in-door tweeters and the sub using the existing MB amps if possible;
2. Must be able to display OBD-2 data, specifically engine temp, ideally trans temp too
3. SD-card or micro-SD card slot for playing my MP3s (or, iPod controls)
4. Works with steering wheel controls and in-dash information panel;
5. Will last longer than the next set of tires.

I'm curious about the OBD-2 data display of the various units, how long after ignition on (or engine start) before data is displayed? A few seconds, or 30-60 seconds?

 

[503865]

I've never heard of a radio that can display OBD-2 data.

You can get the oil temperature to come up on the in-dash display on my 2008 CLK and 2012 R, don't know about other models.

AFAIK neither oil or transmission fluid temperature are not measured by OBD anyway, and I think you need the Mercedes Star software and laptop and leads that go with it to get transmission temperature.

I wonder what you're doing that spanks your car so hard you need to work about transmission fluid temperature anyway :devil

 

[gsxr]

I've never heard of a radio that can display OBD-2 data.

You can get the oil temperature to come up on the in-dash display on my 2008 CLK and 2012 R, don't know about other models.

AFAIK neither oil or transmission fluid temperature are not measured by OBD anyway, and I think you need the Mercedes Star software and laptop and leads that go with it to get transmission temperature.

I wonder what you're doing that spanks your car so hard you need to work about transmission fluid temperature anyway :devil

I've seen photos of Android-based units that display engine data, of course I lost the one photo that I saved about a year ago, in a W211 E55 IIRC. :frown

Engine oil temp is available in the cluster so I don't need that. Coolant temp is the primary item I'm interested in, the W211 bar graph is not only impossible to read, it's also inaccurate compared to SDS live data.

I kinda figured the trans temp would be a long shot, but that would be helpful. SDS takes too long to boot and connect, I need the info pretty quickly after the ignition is turned on. This is for NHRA bracket racing use, btw.

:nerd

 

[503865]

^ Don't work about the accuracy of the coolant temperature gauge, its actually reasonably accurate. True it won't give you kind of 87.12 degrees Celsius readouts, but if you need those you're either called Hamilton or you're missing the point. Zis is a German auto und ve know how accurate ze Germans like to be and all that...

Just figure no steam good lots of steam bad