2015 B8.5 S5 B&O MMI3G+ no more subwoofer sound

189 Views 4 Replies 3 Participants Last post by swissbandit1974, 4 d ago

swissbandit1974

Discussion Starter · 15 d ago

Hi Gents, new here but have some hours researching this issue.

About a week ago i noticed that my MMI lost the sound settings. The bass and treble settings as well as some others where defaulted again. Well, set them back but then i noticed, i have no more sounds from Subwoofer.

Here something after reading all the existing threads: All the people that think the B&O is disappointing, you probably have the same issue i have.. before the incident: WOW, since i have this issue: Blahhhh, sill kinda nice but underwhelming and nothing like before.

What have i done:

3-Finger reset
Factory reset
Pulled the fuse of the amp
Disconnected the amp and reconnected
Opened the amp: no damage visible on the PCB
Unplugged the large 32Pin connector at the amp again and measured the Sub's impedance at pin 25 and 30: it is 2 Ohms
used a 9V Battery on the same pins (cable side) and i did hear the Sub move.

I am at a loss, i can't determine if there is no signal coming from the head unit (note: all other speakers react normally when i increase the bass setting) or if the amp is defective or the subwoofer.

Any tips?? Please? I have a spare amp, factory sealed. But if i open it, i have to buy it. That could be a costly test to do..

Oh yes, another question. I got the cabriolet.. how the hell do you remove the rear left side panel to get to the subwoofer? Especially the belt mechanism seems to be a nightmare.

Please guys, any help or tips or experiences?

Thanks a lot

Andy

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JohnS4

· #2 · 13 d ago

Welcome. You will have to scan the car for fault codes. That should point you in the right direction.
Also worth checking in the boot for damp and water ingress. That is known for breaking the amplifiers.

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swissbandit1974

Discussion Starter · #3 · 13 d ago

Hi, I will get my Carly hopefully tomorrow and i will check for error codes. I opened the amp and there is absolutely no visible.damage to the circuits. No dampness in the boot either. There are so many post about bad subs (not many B8.5 S5 Convertibles though) and very few actual solutions. Defective amp is mentioned a lot bir really identified as the root cause.

Nobody seems to know how to access the sub. It is behind the side-panel behind the driver. If i could get to it, I could quickly wire it to a spare sub i have form an old stereo. I will.post the codes if i have an soon. Thanks for your help

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SimonRoma

· #4 · 11 d ago

Swiss me ol fruit cake. 90% moisture, 8% amp is deceased. 2% however could be your car battery.

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swissbandit1974

Discussion Starter · #5 · 4 d ago

JohnS4 said:
Welcome. You will have to scan the car for fault codes. That should point you in the right direction.
Also worth checking in the boot for damp and water ingress. That is known for breaking the amplifiers.

Hi, finally i got my Carly. no fault codes. So now i am lost. However, Carly cannot connect to the MMI ECU.

I don't know any way if i can check if there is no signal coming from the MMI in the first place, or if there is no signal going from the AMP to the Sub.

Does anyone know what the two optic fibers do? Is one Amp-MMI and the other MMI-Amp? Or is one front speakers and others back? I mean the rear speakers are working. Not very loud but they do emit sound.

I know the cables between Amp and Sub are good. I can measure the 2 Ohm impedance at the disconnected 32-pin plug at the amp.

Should i chance it and install the brand new Amp.... or shall I go to an Audi shop and have them run a diagnostics scan? Which will cost a couple 100 Bucks too..

Any help / Experience is appreciated.

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