Speaker Subs whining after shutoff

[MrStickles]

Just got my bike back from the dealer for brakes and they also did a software update. I now notice that when I power down the bike I get about 5 seconds of whine or reverb of some type from both subwoofers. After that about 30seconds later I get an audio crack from them, I’m guessing when the power finally disconnects. I’ve checked the fuses and they all seem ok. The speakers both do work when the bike is on. Any ideas? I’ve cleaned all of the fuse contacts and replaced the 15, 20 and 50 amp fuses. The 20 and 50 looked a little funky on the contacts but nothing horrible. Could this be something that happened because of the software update?

 

[Star-Lord]

I didn't even think of checking my software version after the Reverse Recall work was performed...

 

[Aussie-Hoss]

Just got my bike back from the dealer for brakes and they also did a software update. I now notice that when I power down the bike I get about 5 seconds of whine or reverb of some type from both subwoofers. After that about 30seconds later I get an audio crack from them, I’m guessing when the power finally disconnects. I’ve checked the fuses and they all seem ok. The speakers both do work when the bike is on. Any ideas? I’ve cleaned all of the fuse contacts and replaced the 15, 20 and 50 amp fuses. The 20 and 50 looked a little funky on the contacts but nothing horrible. Could this be something that happened because of the software update?

Check your connections under the seat. I had the same problem when connecting a Canbus for my trailer plug. The Canbus would fit into the under seat wiring - but this is NOT where they should go. Canbus wiring is connected into the DWA unit (in front of the battery on the left side of the bike).

 

[MrStickles]

Everything looks connected and tight near the battery. But… what is supposed to screw in the open hole?

 

[Aussie-Hoss]

Nothing, unless you're going to use it as an earth point - which I did for the canbus - takes an M8 thread.

 

[harrisrc740]

Do you have any recent additional power hookups? Such as lights, powered phone craddles.... If so check the polarity of those connections.

 

[MrStickles]

Do you have any recent additional power hookups? Such as lights, powered phone craddles.... If so check the polarity of those connections it went to have the re

Do you have any recent additional power hookups? Such as lights, powered phone craddles.... If so check the polarity of those connections.

It went and had the reverse disabled, and a software update. I’ve checked all the fuses, battery connection, looked for any worn wires. My optimate battery tender is showing green and yellow on the battery test so I guess that means it’s about 80%. When I turn the power on it’s showing 12.4amps before the start. Riding season is almost done for me. Having hand surgery this week which puts me out for at least a month so I’ll be well into December in Pennsylvania. Hopefully the reverse fix comes and I’ll let them check the subwoofer then.

 

[physiqo]

Any update on the issue? Just to be clear, before they did the software update, was there ever a faint tone or power-down click from the audio system upon shutoff? Also do you notice clicks or pops when powering on the bike?

Click and pop suppression is actually a common feature on audio amplifier ICs. I have no clue what BMW chose to use on the R18s but it could be that the circuit behaves differently at different temperatures and so you noticed the output noise more prominently after getting it back (in the fall)? This is typically a hardware level thing, so the capacitors and resistors used in the circuit define whether or not popping happens during power on/off. If you're familiar with circuit diagrams and feel so inclined, Texas Instruments makes several amplifier ICs that have this feature and you could read the "CLICKS AND POPS" section of the LM4766 data sheet, for example.

Again, no clue what's actually in there so for all I know some parameter in the software may have changed and now the system pops but I suspect that's unlikely IMHO. It's possible that a loose connection like @Aussie-Hoss was suggesting may cause weird behavior on one of the power rails to the amplifier but it sounds like those connections haven't been altered (confirm?). Have you told the dealership? They can be clueless when things get too technical but it might be worth having them consult with BMW to address it if it's really bothersome.

Hope your hand is healing well! Interested to hear what you find.