I might have found the source of the speaker static problem (kind of)

[JCtx]

Hey gang, I've read several complaints about weird speaker static. Mine was more of a shrieking noise for a moment, but I bet the source of all those static noises is the front tweeters as well.

Here's what I noticed on my Nav-equipped coupe: every time I open a door (either one, and I bet with the trunk as well), I hear the nav unit 'boot up' (sounds just like my computer), then spins for a few minutes. The weird thing is this happens even without my CA key in range, but am sure EVERYBODY with Nav will have this 'problem', although I can't understand why without the ignition on.

The potential problem I'm concerned about, and what I want you to report back here is this: If you put your ear next to the door tweeters while the spinning takes place (a few minutes after every time you open a door), and listen for a low-volume static noise (hence putting your ear against the tweeter). When the spinning stops, noise goes away. THAT can't be right. Or maybe it is (we'll see how many of you respond), but our amp shouldn't be powering up the freaking tweeters without even a key in range (with ignition ON, I'd understand).

I have many questions: Why the hell is the nav loading and spinning without even the key in range? My automotive stethoscope points to that, by the way. Now, the Nav unit is not connected to the front tweeters directly, so the problem sounds like the amplifier powering the front tweeters, but is there another interface between Nav and amp, or amp and tweeters? Finally, if somebody gets the loud static again, please confirm where it's coming from; I bet it'd be from the front tweeters as well.

Any guesses what's the culprit? Something is shorting out, but where, how, when, where??? All comments welcome, and thanks in advance for your help.

EDIT: Can somebody without Nav try this please? Maybe it's the CD player. And for the ones responding, please state if you have Nav and/or premium sound (it uses different amplifiers). Just trying to isolate what option combination has the potential problem.

[Grey Space]

The "key" does not power the car. The car is always powered, unless you physically disconnect the battery.

The "interface" between the Nav unit and the car audio is that they are not really separate - they are just components in a large integrated system. So there are no "direct" or "indirect" connections, because they are all on the same bus and all controlled by a host processor.

You are making the mistake of thinking about your vehicle in terms of separate components. It's not made that way. Think of it as a completely integrated computer on wheels.

So, a slight programming bug or momentary surge when something switches on or off can manifest itself as wierdness in seemingly unrelated stuff. But that's the thing - nothing is unrelated.

[Technic]

Opening any door or the trunk turns on the iDrive DVD drive (preloading the DVD data) and the OEM amp, regardless of having the key in the ignition or not.

[Grey Space]

Originally Posted by elp_jc

Now, the Nav unit is not connected to the front tweeters directly

BTW - the Navigation system speaks to you through the audio system, so I wonder why you could have thought that there's not a "direct" connection.

[BMWM.D.]

JC,
The CCC (audio system controller/nav unit) is a complex head unit consisting of 5 different control modules. This is the "gateway" module for the MOST bus, which is a fiber-optic bus system that is used for the audio/communication systems. It was first introduced in the E65/66 7 series and has since trickled down into all new BMW products. The only car currently being made that doesn't have a MOST bus is the X3.

Anyways, the amplifier is on the MOST bus if you have the high-end audio system. BMW refers to the high-end audio systems (ie. logic 7 or the individual audio system in the M3) as "top Hifi". When you open the door, the MOST bus is most (no pun intended ) likely woken from sleep mode. I suppose it is designed this way so the CCC can begin to boot up before you actually start the car and drive off. When the MOST bus comes up, the amplifier is also powered up which could explain the sound you hear from the speakers.

So yes, the front tweeters are in a way connected to the Nav system. The speakers are hard-wired to the amp and the amp is connected to the CCC via the MOST bus. I think this explains what you are experiencing. Is it normal? That is a good question, but I have not noticed it in my car (and I have Nav & premium sound).

Is it something to be worried about? I don't think so, but it does show you the consequences of frequent locking/unlocking and the amperage draw that comes with disturbing sleep mode. This is one of the things the vehicle monitors to help diagnose battery charge issues (in addition to short trips, lights being left on, excessive storage time, etc.). Each time you open a door or hit the remote button, the bus systems wake up and it actually takes the car about an hour to completely enter sleep mode. Just something to think about if you have a kid at home who likes to play with your remote key.

[JCtx]

Originally Posted by BMWM.D.

Is it normal? That is a good question, but I have not noticed it in my car (and I have Nav & premium sound).

Hey, can you put your ear on a tweeter to know if it's normal to have some static? I can't hear it without getting pretty close (heard it by accident while cleaning that wax-like crap on my door hinges, which forced me to put my head next to the tweeter), but if your car doesn't make that noise at all, I found the problem with my car. Something had to trigger that super loud shriek; something's not right in there, otherwise I wouldn't even bother. Don't want to deal with that ultra expensive, 5-module system out of warranty (plus troubleshooting charges ).

Thank you very much for your detailed explanation man; everybody else missed what I was asking. I'm not used to anything 'self-powering' without at least the 'acc' mode, but now I know how it works (thanks again). And yes, I'm aware this car discharges the battery quite a bit when working on it so I charge it twice a week.

The issue is knowing which of the 5 modules you mentioned could be my problem, since I'm sure no code is thrown. And FYI, at least 2 guys have reported loud static that didn't go away when opening the trunk; at least my issue was momentary.

Hope some of you take the time to put your ear to the speaker when entering your car; takes a second. I'd appreciate it. Thanks.

[Grey Space]

Originally Posted by elp_jc

Thank you very much for your detailed explanation man; everybody else missed what I was asking.

No, I don't think so. My point is that you are chasing down a rathole. I don't know anything about your "loud shriek," but whatever that was, I don't think it has anything to do with the low-volume RFI noise that is always present in the audio system when the Nav DVD spins up. That is, as I said, a side effect of the integrated nature of the bus-attached modules.

If you feel your car has a problem, you need to look elsewhere, because this line of inquiry isn't likely to get you anywhere useful.

[BMWM.D.]

Well, the 5 modules I was talking about are just what are installed in the CCC itself. Most of the individual parts of the CCC are replaceable on their own, but usually when a problem occurs we replace the entire unit ($2k+).

The situation gets more complicated due to the nature of the MOST ring. Any one module on the MOST bus can cause an issue with the audio system. Besides the CCC, there are several other modules on the bus. Depending on options, there is the Amp, TCU (telematics), Satellite radio, CD changer and ULF module. Any one of these modules could be the cause of your problem.

As an example, I had a 745i a while back that came in for a problem with the audio system. The owner said that once in a while a ticking sound would appear from the speakers while listening to the stereo. He said the sound traveled around the car, from speaker to speaker like it was some sort of self-test. He had brought the car in a few times for this in the last few years, but nobody could ever duplicate the problem. I finally got ahold of the car and was able to make it happen. It was a strange problem, really. After some troubleshooting and studying the wiring diagrams, I found the problem. Turned out to be the telematics control unit (TCU). This module is strictly for the BMW assist and bluetooth systems, but it was wrecking havoc on his entire audio system.

I will take a close look at my car next time I go for a ride to see if I can hear anything. Either way, I wouldn't be too concerned about the noise or your warranty coverage right now. You have a long way to go before that is a problem. I'll let you know if I find anything.

[FlyFish]

Originally Posted by Grey Space

The "key" does not power the car. The car is always powered, unless you physically disconnect the battery.

The "interface" between the Nav unit and the car audio is that they are not really separate - they are just components in a large integrated system. So there are no "direct" or "indirect" connections, because they are all on the same bus and all controlled by a host processor.

You are making the mistake of thinking about your vehicle in terms of separate components. It's not made that way. Think of it as a completely integrated computer on wheels.

So, a slight programming bug or momentary surge when something switches on or off can manifest itself as wierdness in seemingly unrelated stuff. But that's the thing - nothing is unrelated.

And what is a 'key' without the 'Nav' if no one is interfacing with or without such complicity of someone holding the key near the components of manifest at the source of the computer on wheels? Such fastidious interpolling of said complexities can or can not be said with truth or reality as the balance fluctuates in and out of our preceived matrix Neo...

[JCtx]

Originally Posted by Grey Space

I don't know anything about your "loud shriek," but whatever that was, I don't think it has anything to do with the low-volume RFI noise that is always present in the audio system when the Nav DVD spins up.

For now all I want to know is if other cars with iDrive and enhanced audio have that low-volume RFI noise to see if it's normal or not. I'd appreciate if you just say if you have the noise or not, and let somebody like BMWMD with MUCH more knowledge than you decide if I'm chasing a rathole or not. Sorry for trying to understand what my problem could be; you could learn something from this thread instead of being so negative. Please don't ruin my thread; thanks man (you're on my 'ignore list' now so no need to reply again).

BMWMD, as always, thanks a million for your great insight and explanation. Thanks to you, I understand much better what kind of ghost I'm dealing with here. And makes perfect sense, as bluetooth and BMW assist also use the tweeters.
I'm not worried about it for now, and I don't think I'll be as lucky to be the only car with the low-volume static (that'd be GREAT , but still have to hear from somebody on this) to get my system replaced now, but will be watching the other threads about the loud static noise for further education on the possible fixes. And yes, I'd really appreciate if you could relay your findings next time you drive your car. Take care, and have a great weekend.

[Grey Space]

Seems like you have bigger issues than problems with your car. Hope you find a way to resolve them all.

[BMWM.D.]

Always glad to be of service

So JC, it seems like this is normal for cars with CCC and Premium sound. As an update for you, I checked out my car this morning before I left for work. I unlocked the door and opened it. Before I touched anything else, I put my ear up to the tweeter. Sure enough, there was a very slight static noise. It is so faint that you really have to be trying to hear it, though.


I doubt this noise has anything to do with the other "shriek" noise you heard. Come to think of it, my car did something strange like that shortly after I took delivery. I think I was either locking or unlocking using my comfort access, and there was a sudden, loud noise from the audio system. It actually kind of startled me. Hasn't happened since in over 6 months, so I'm not worried about it.

Hope this answers your question and enjoy your ride,

[Grey Space]

Originally Posted by BMWM.D.

So JC, it seems like this is normal for cars with CCC and Premium sound.

I doubt this noise has anything to do with the other "shriek" noise you heard.

I believe I said this already. It's nice to be vindicated though