stereo replacement
 

simple question is upgrading stereo on 2004 sl600 - stereo seems to be going bad - big job to replace? Should I just have it repaired? Basically, trying to understand if replacing stero is an easy swap or if it is somehow connected to the computer and therefore swapping stereo now gives other items trouble. If so, what are options. Thanks!

It can be done, but there are some complexities. First of all, the system uses fiber optics to send audio signals from the head unit to the CD changer and amp mounted in the trunk. This means that there is no "speaker wiring" in the dash. You will need to run your own speaker wire from the dash to the trunk, disconnect the Bose amp, and then tie into the an analog speaker wiring there. It's not a big deal, jsut a little extra work to run the wiring. Of course if you want to go beyond your new head unit's puny built-in amp and install a separate amp, it's the same - run pre-amp wiring from the dash to trunk, install your amp there, and tie into the high-level speaker wiring at the harness for the (now removed) Bose amp.

Another small challenge is that the wiring harness for the radio does not have circuits for switched 12v+ or illumination. The factory radio gets these signals from the CAN bus. Your options there are to either tie into the cigarette lighter and ashtray for those circuits, or, get a CAN bus interface. There are CAN interfaces available that will allow you to use your steering wheel control buttons for the aftermarket radio. Many of those also supply the switched 12v+ and illumination circuits. just make sure you get the proper type - your car uses the pre-facelift CAN signals with D2B fiber. The other type is the My2005+ facelift CAN with MOST fiber.(which would not work in your car).

This won't affect any other functions of the car. I would mention TeleAid, but since yours is a MY2004, it is defunct anyhow as it's on the old analog cellular network, so no worries there. Also, even with that CAN interface, I am not aware of any way to get the radio display on the instrument cluster as you'd have with your factory unit. However, there are some aftermarket "drop in" head units from China that claim to be plug and play. I have not heard great things about these, so I would not recommend them. If you do go looking, make sure you are shopping for a pre-facelift D2B version.

One other thing are the speakers. Most people do not like the sound of the 2ohm Bose speakers once the Bose amp has been removed. Apparently, Bose uses fairly inexpensive speakers, but them has special digital processing in the amp to make then sound decent. Also, make sure your radio or amp is capable of driving 2ohm speakers.

Thank you very much for taking the time to try and help me. Great info that will be a big help to me. I have two other questions if you could.

First - the reason I asked about a new radio is because every once in a while the CD player and speakers will both go out at the same time. I assume that is due to a wire or some other part that goes from the knobs/stereo back to the CD player and speakers - like a harness or such. Also it only happens when I shut/off turn car back again which leads me to believe it is not a loose wire - any ideas?
Second - when the time comes to replace stereo I will want something that is an easy swap and can use my cell phone for a lot of things like Waze for map directions, outgoing phone calls and would really like to keep all steering wheel functions as discussed. Is there a vendor you know of that will have experience with swap out on 2004 SL600 and will at least be happy to give advise on the radio install if we are buying from him? Have my company mechanic who does great work on my cars but knowledge and experience makes his life much easier.

THANKS !!

Check out a few local audio shops in your area and see what they can do for you. A good shop can make it look basically stock with all features you want. Expect to pay around $500 to $1200 for the head unit to do all the current things people want.

The amp and CD changer are all connected to the head unit via the fiber optic loop. If there is a problem with the fiber, that could be the culprit.

Again, thanks for trying to help me. Is there a schematic, photos and locations of all components somewhere on web or mbworld? 2004 SL600. Need to know where to look for bad connection - rather not pull apart anything that does not need to be pulled - thanks again!

Try taking it to the dealership for the diagnosis. It may end up saving you money in the long run.

When COMAND powers up it sends an electrical "wake up" signal to each of the components on the D2B optical bus. Your CD changer may not be receiving or responding to that signal.

To test the wake up signal and other aspects of your vehicle's audio you ought to invest c. $350 in a Star Diagnosis system.

Schematics and component locations for many models are here: http://www.sf.nexedge.com.my/. Viewing is easiest if you have Windows XP and a plugin from Autodesk called "Whip". An alternative method for viewing schematics is explained here: http://www.benzworld.org/forums/r129...l#post17477509.

Ok, got it, thanks. I assume that it sends the wake up signal and if there is something wrong it shuts down both the speakers as well as the CD. I assume that because it appears (as far as I can tell without sound) that the only things not working are the speakers and CD. Can you tell me where the D2B optical bus is? Also where I can buy the $350 Star DIagnosis system you suggest. Have not looked for one in a few years and, as I remember, back then the choices and peoples opinion of them - at $350 - was not too good - as I remember - could be more like 5 years but you get the point

I do not know in detail where you will find the optical bus, nor can I imagine how this would be of interest.

You can buy a C3 multiplexer with software for $244 here: https://www.obdsvs.com/car-diagnosti...-and-cars.html. There is an array of sellers on aliexpress.com as well. I recommend getting an external hard drive with software pre-installed for a Dell D630 laptop. The Dell can be had for $60 from eBay.

From a stereo signal the factory audio in an '03 R230 derives 4 channels of audio source material that feed 7 channels of amplification used to power 8 speakers. Incorporated into the Bose amplifier is custom digital signal processing and equalization.

If someone has a link to an aftermarket install that matches the technical excellence of the factory system, kindly link to it on this thread.

@Rudeney it seems that you know your stuff when it comes to stereos. Can you recommend me one?

Sorry for being off-topic. I'm looking for a good stereo and can't make my mind up which one is the best.

There are so many aftermarket stereos that it's hard to find a good one. Many of them have one digit difference in their name. Anyways I've been reading reviews on the nets and they are all hype. Most of them downplay the negatives and hype features like 7" as if it would be that important. I've found a different blog and I've set my heart on the kenwood dmx 7706s. The thing I liked about this blog is that it says it how it is. No sugar coating no BS. This kenwood review is a bit critical. It has highlighted some flaws that put me on the fence. What do you say?

Any tips?

I'm not exactly sure how the 03' Comand surround system works, but on the 05 and newer (MOST), the signal coming from the Comand head unit is indeed just 2 channel, but if the source is multi-channel, it down-mixes it Dolby Prologic or something similar, where the Rear Channel and LFE information is multiplexed on top of the normal from Left/Right channels. The Bose or the HK amps then de-mux the signal into the discrete channels.

The problem is that the head unit must tell the amp to decode the signal, it's not done automatically. So even if your head unit can output 2 channel multiplexed surround audio, I don't think the Bose amp would play it in surround, because there is no instruction from the head unit to enable the surround sound decoder.

I had to read my old post many times before I understood what it meant to say.

I don't think music ever plays out of the center speaker on the dash; also, music only plays from the rear speakers if one of the "spatial" options is selected from COMAND. So with ordinary stereo there would be 3 channels of source material (left, right, subwoofer) and 5 channels of amplification (left-high, left-low, right-high, right-low, subwoofer). If a spatial option is selected, there is an additional source channel (rear) and an additional amplification channel for same.

The Bose speakers have no crossover network, so the tweeter and woofer drivers are electrically independent. Frequency division is done within the Bose amplifier to create "high" and "low" signals for both the right and left stereo channels.

I tried quite a few times to listen to surround soundtracks on my old Comand radio, and if I fed it a DVD movie, I could indeed get surround. I did play my Star Wars DVD, and the rear channels contained rear surround effects like they should, and I could swear the voices came from the front center speaker.

But when I used the surround effect on my iPod source or MP3's on a DVD (surround was not available from radio), you could hear the rear channels, but there were basically a fake surround, with the same audio as the front, but slightly delayed. And I don't think the center speaker did anything. However, the center speaker seemed to work with the phone.

So this is why I said that if the source contained a true surround sound track, the system I believe multiplexes the surround, LFE and center channels into the front L/R channels and sends it out as a stereo signal to the AMP, which demuxes it and sends it to the appropriate speakers, assuming the surround function is enabled from the head unit.

This is how Dolby Prologic / Prologic II works. If anyone remembers the good old days of LaserDiscs and SVHS, those devices did not have discrete surround output in the early days, they only had stereo, but the movies were encoded in Dolby Surround and Dolby Prologic, and if you had a proper receiver, it decoded the sound into full 5.1 channel audio. Only later, did discrete multi-channel audio came around in the form of Digital Dolby, and DTS, etc, and the devices started to use optical cables like TOSLink.

The last thing I put in was a Pioneer AVIC in my C240, and that's been 14 years ago. That radio was decent, but it actually ran Windows CE, which was a bit slow, though there were ways to customize it. I'd probably look at something that runs Android OS. Also, I like the ones that have some hard buttons for things like volume, mute and source selection.