Speaker rumble?

[n13]

Just recently my rear nearside speaker does a strange rev-linked rumble (see video Here).

The video is of me connecting and disconnecting the main speaker (tweeter doesn't seem to do it). this video was recorded with the Comand turned off but presumably the amplifiers are all on anyway?

It looks like when the connector is connected, the cone is pulled into the magnet then slowly extends (not back to normal position) and then gets pulled in again.

It happens quicker as revs increase but only this one speaker.


anyone help?

 

[John]

That's really weird.

It's sort along the lines of what you get when car audio is not properly-grounded (i.e. not "attenuated well") but just on that one speaker.

If I was a betting man I would bet there is a / are break/s in the wires to that speaker and / or a problem with the output channel on the AGW (Audio GateWay which is an interface and amp combined for the audio part of COMAND if I understand it correctly).

Something like someone screwed through the speaker wires or similar.

I would start with the wire as it is cheaper then repairing an AGW!

You could just test that one speaker on the other side or on your house stereo if you have one - just to check it works fine but I suspect it will be fine.

The only way I can think of is tracing the wires back from that speaker to the boot (where the AGW is - normally on the left of the boot behind the carpet I believe... or at least that always seems to be where it is on the Mercs I've had) - just to see if there is an obvious issue although you might not be able to see the whole cable run.

I am not expert-enough in electronics to know if there is a way of testing the wires (by removing the wires plug from the AGW and using the pins that represent both wires respectively - up to the end of the speaker) - maybe someone else might know if there is a way to test that?

Worse-case, you might need to run new wires.

 

[optimusprime]

You get this if the wires are crossed over,, but this is not possible if the positive conector on the speaker is larger than the negative wire . Did you fit this radio or is it original radio ?. Look further at the wires and conections going to the radio receiver . There could be damp ,only a guess .

 

[n13]

Thanks for the replies. I went out to check the wires with a multimeter to see if there was some pattern of large voltage over the two. And I got nothing so plugged it back in and its working OK... I'll see if it does it again then investigate whilst it's doing it.

 

[John]

Thanks for the replies. I went out to check the wires with a multimeter to see if there was some pattern of large voltage over the two. And I got nothing so plugged it back in and its working OK... I'll see if it does it again then investigate whilst it's doing it.

Could be something as dopey as it not making a good connection and plugging it back in removed whatever contaminant was stopping a good connection.

A plug plugged-in doesn't guarantee a good connection.