Comand auto volume all over the shop!

[meb]

I have a strange problem in my SL500 R230 with D2B Comand 2.0. The volume increases and decreases of it's own accord and is really anoying. Even sometimes when just sitting still it will fade up very quickly when there is no increase in background noise.

Any ideas how this can be fixed? Has gone back to dealer once who tried softwre reset but this did not work.

 

[GazCaff]

Are you having any problems with your cruise control or ABS?

 

[meb]

No, none at all.

 

[television]

Too late tonight,,but I will have a look later but I have never heard of this

 

[jadefox]

Funny you should mention it, I did have this once or twice myself last week - but for me, it may be the auto volume (I didn't even realise there was an auto volume!!) is there any way of finding out what level you have your volume set to?

Could it be that you actually have it turned up to a higher volume than you think but it's a speaker playing up? Does the sound kind of cut in louder or does it sound like someone is physically turning it up gradually?

 

[meb]

Yes, I agree I think it is the auto volume but there are no menus to adjust this.

It is not a speaker problem and it is as if somone is quickly fading the level up and down when it happens. I think it may be either the Comand auto volume circuit or the sensor?

Anyone know how this auto volume works? Is it from the speed pulse or from a microphone/SPL sensor somewhere?

 

[television]

Yes, I agree I think it is the auto volume but there are no menus to adjust this.

It is not a speaker problem and it is as if somone is quickly fading the level up and down when it happens. I think it may be either the Comand auto volume circuit or the sensor?

Anyone know how this auto volume works? Is it from the speed pulse or from a microphone/SPL sensor somewhere?

All of these things work from speed pulse,,I am sure it can be disabled in the sound menu

 

[MBManInKen]

All of these things work from speed pulse,,I am sure it can be disabled in the sound menu

According to my manual, on my car (with the Bose system), this works by picking up the cabine's ambient sound levels through a microphone and processing that signal to determine adjustment. That makes sense as what matters is the volume of background audio, not the speed of the car (driving on cobbled roads can be louder at lower speeds than driving on a well designed motorway at higher speeds).

 

[meb]

According to my manual, on my car (with the Bose system), this works by picking up the cabine's ambient sound levels through a microphone and processing that signal to determine adjustment. That makes sense as what matters is the volume of background audio, not the speed of the car (driving on cobbled roads can be louder at lower speeds than driving on a well designed motorway at higher speeds).

I think this seems to make more sense to me as if it was just speed pulse surely my nav would also be misbehaving.

Assuming the SL uses this method like the S does, anyone know where the microphone and processor is?

 

[television]

According to my manual, on my car (with the Bose system), this works by picking up the cabine's ambient sound levels through a microphone and processing that signal to determine adjustment. That makes sense as what matters is the volume of background audio, not the speed of the car (driving on cobbled roads can be louder at lower speeds than driving on a well designed motorway at higher speeds).

I do not think that this can be so on a open topped car,, see what I can find

 

[MBManInKen]

I do not think that this can be so on a open topped car,, see what I can find

Good point - my s-class could of course be different from other models.

 

[meb]

Maybe it is disabled when topless..?

One thing I do remember once, the volume shot up when the sun visor closed with a loud snap but I was unable to repeat this effect with any reliability. This may be some kind of a clue..

 

[television]

I will have to come back to this.

There is the interior motion sensor, but this is only for the alarm, and switchable from the console.. The microphone for that is the small grill under the mirror nearest the screen

 

[Ted]

According to my manual, on my car (with the Bose system), this works by picking up the cabine's ambient sound levels through a microphone and processing that signal to determine adjustment. That makes sense as what matters is the volume of background audio, not the speed of the car (driving on cobbled roads can be louder at lower speeds than driving on a well designed motorway at higher speeds).

Does that mean that if you turn the volume up, like really loud, that it will detect this and turn the sound up even more?

 

[television]

Nothing found yet as to where it comes from,, on the audio 30 it defiantly was a speed pulse as I have worked on those

 

[MBManInKen]

Does that mean that if you turn the volume up, like really loud, that it will detect this and turn the sound up even more?

No, the DSP obviously knows its own output and is able to ignore that. That type of audio processing (filtering out your own input) is actually reasonably simple.

 

[jadefox]

According to my manual, on my car (with the Bose system), this works by picking up the cabine's ambient sound levels through a microphone and processing that signal to determine adjustment. That makes sense as what matters is the volume of background audio, not the speed of the car (driving on cobbled roads can be louder at lower speeds than driving on a well designed motorway at higher speeds).

Does that mean that potentially my kids could set it off? They can get pretty rowdy in the car at times!

 

[MBManInKen]

Does that mean that potentially my kids could set it off? They can get pretty rowdy in the car at times!

Sounds likely they would set it off .

 

[television]

I cant spend anymore time looking to see where it comes from

Nothing listed in the known faults

 

[meb]

Thanks for trying. Back to the dealer...