[jinjur]

Hi gang, hope someone can help or advise

We have a 2014 F31 325d (UK car) with pro nav HK and L7 audio

Car has been fine for 5 years but last week the audio went weird.

Seems to be from all sources (radio, media, bluetooth) and notably all of the system sounds as well.

I have attached a video and you can hear the distortion most notably in the gong in that video but it is present in all sound.

I have changed all settings in the HU to try and isolate it but the distortion is in all speakers. I have tried with L7 on and off, no change

I reset the HU as well, no change

I have checked for errors in ISTA and nothing is shown

Only other notable thing is that the other day the car started asking us to select a profile every time it was started. This hasn't happened in about 5 years of ownership. I went in and turned this option off but I guess the reset might have triggered that.

https://youtu.be/N5l0sq1Xp7E

I had a look around the amp in the boot area as i knew that the E9x series had issues with water ingress affecting the amp but it is all dry

At a loss guys so really hoping you can help

Can't really be throwing a fortune at this for BMW to muck about and I am fairly hands on with things so happy to investigate if you can help me

Cheers

Jinj

[Onizukachan]

Borrow a mates amp and see if that resolves it?

[jinjur]

Nobody I know drives one of these buddy......most people have moved on to newer models etc

[Onizukachan]

Can you get one from junkers then, cause that’s what I’d start with since it is all sources all speakers.

[jinjur]

Trying to source one at the minute but they are all £600+ which is A LOT and not even remotely feasible to try something out.

Am I able to put in a non-Logic7 amp?

Like one from the basic model or anything~?

J

[Billfitz]

It could be the amp, could be the head unit. The usual method for testing either would be with another amp. If a different amp doesn't fix it then the head unit is the likely culprit. By no means do you want to buy an amp without knowing if that's the problem, so your only alternative may be going to a shop that has an amp on hand for test purposes.

[jinjur]

Just thought I would post an update here.

So, well, I really don't have the $$ to throw at an amp on the off chance and unfortunately I am not in a position to test it out with a known working one.

I have pinged multiple BMW breakers here (Northern Ireland) and they either don't have any cars with this specific spec or they know exactly what they can ask for them and that is usually upwards of £600.

So I spent a little time in the car trying to work out what was going on as this doesn't really fall into the water damage/sound gone situation that usually happens.

Anyway, I have discovered that this noise is 100% isolated to the centre/dash channel.

It was hard to actually identify that because of how intrusive and loud it actually is but I was able to trigger each channel in isolation within ISTA and noted the centre channel was the only one that sounded off.

So I have disconnected that main speaker (at the mid unit which looks to kill the tweet too) and the car sounds better

I am going to try and remove the speaker unit (mid and tweet) in its entirety so I can test the speakers themselves but I guess, is it likely that the centre channel on the amp only would crap out like this is or is it more than likely the speaker?

J

[Billfitz]

The speaker is more likely to be blown than the amp. Finding those used at a reasonable price should be easy, as there's lots of guys who fell for the advertising hype and bought replacements.

[Onizukachan]

Super easy to remove with a 1/4 drive socket and t20 bit.

[jinjur]

Appreciate the input guys, will hopefully get to test the speaker tonight.....might just use another channel in the car to test or I will jerry rig it to my wee car which is much easier to pull apart.......its French, its basically ALWAYS apart

[Billfitz]

What you describe may be a bad voice coil former. Remove the midrange, gently push the cone in by 3mm or so, with your fingers spread around the cone to provide even pressure. If you feel or hear any scratching the voice coil former is toast. You may also connect and disconnect a 1.5v battery to the terminals. The cone should move without any scratching noise, producing only an audible click when you make the connection.

[jinjur]

Originally Posted by Billfitz

What you describe may be a bad voice coil former. Remove the midrange, gently push the cone in by 3mm or so, with your fingers spread around the cone to provide even pressure. If you feel or hear any scratching the voice coil former is toast. You may also connect and disconnect a 1.5v battery to the terminals. The cone should move without any scratching noise, producing only an audible click when you make the connection.

Super suggestion brother. Will do exactly this and report back. Thanks

[jinjur]

Amp I fear.

Disconnected the whole centre unit and connected it to an old cinema speaker that I had lying around (known to be fine)

Same distortion came through

So I guess I can live without the centre but out of curiosity, does anyone on here know the ins and outs of the amp~? i.e. does the centre channel have its own amp? what is it (fet & cap etc)? does the centre channel come in through the MOST cable? could it STIL be the headunit?~

J

[Onizukachan]

On all prior bmws the output from head was stereo. The amp creates the fade, balance and center from the two stereo L/R outputs.

Know any OG stereo repair guys? I bet they could fix it,probably is just a bad mosfet.

[Zingaling18]

I have the same issue with gong sound and what I believe to be ASD when under high acceleration. The sound seems to be coming from the driver side door speaker.