[smlong79]

Hi all - I've posted on this earlier in other forums regarding a recurring issue I've had with the "premium" audio system in my 2016 340i. I'm posting an update here in the hopes someone can point me in the right direction.

Since I took delivery of the car (June '16), the left (driver's side) front tweeter has worked only sporadically. The problem started as random but persistent crackling and popping and eventually developed into complete cut-outs/signal drops of the high frequency portion of content for extended periods of time. The problem occurs during playback from all sources - AM/FM, satellite radio, CD, bluetooth iPod, USB iPod, and even bluetooth telephone. Audio sources which are primarily mid-high frequencies (e.g. voice - radio and telephone; and melodic guitar - jazz and blues) are the worst.

I've taken the car into the dealer to address the issue 4 times. The first time, they ran some diagnostics but found no problems, so no repairs were performed. The second time, they detected some "shadow faults" in the amplifier and so they replaced the amplifier. The problem seemed to be fixed for a week or two and then returned. The third time, they ran diagnostics and again found no issues; however, they did jiggle the elephant trunk between the A-frame and the door and again, the problem seemed to be fixed for a week or so and then returned. I then complained to BMW NA and when I brought the car in for the fourth time, the service manager sat in the car with me and acknowledged that the left front channel sounded muffled compared to the right. Without running any diagnostics, they simply replaced the left front component speaker set.

After they replaced the speakers, I thought for sure the problem was fixed. I used to install high-end custom car stereos in a previous life, and the symptoms I was observing led me to believe I had a failed speaker set (the tweeter dome, in particular). Unfortunately, the problem again seemed be fixed - this time for several weeks - but just recently I noticed the left front tweeter cut out again for a period and then emit a few crackles. The drop out seemed to coincide with some bumps in the road, but not particularly hard ones.

I think there definitely was a problem with the original speaker pair, as the audio playback has been much better in general since they replaced the speakers. However, I'm now thoroughly exhausted as to where else the problem could lie and I am so tired of taking my car into the dealership to chase a ghost. Because the problem is difficult to reproduce on command, we will waste more time troubleshooting with no smoking gun.

Does anyone have any recommendations for what I should do next with BMW? At this point, I'm tempted to pursue legal action through my state's (NC) lemon laws. If not legal action, are there any BMW audio experts out there who might have a suggestion for where else the problem could lie? At this point, I think the only thing we haven't positively checked is the head unit, but wouldn't a head unit problem show up in the diagnostics?

[claykin]

Based on what you say has already been troubleshot and replaced, sounds like they should be looking for a pinched wire in the harness going to that door.

or try replacing the headunit in dash. The amplifier only amplifies the low level signal input. if that signal is messed up, you get an amplified version of that.

[Kevin @ Integral Audio]

Personally, I would not suspect the headunit - the HU puts out 4 channels, if you were losing one of those you'd lose the entire tweeter/mid/underseat woofer. the strange part is that it went away after they replaced the speakers. Did you experience any other long periods without trouble, similar to after they replaced the speakers?

The sound you describe does match what would happen if you had a had an intermittant chassis short on the tweeter wire. I haven't checked the wiring diagrams on the premium (I assume harman/kardon in your case?), but I believe the topology is the same as the HiFi, with the tweeter and mid sharing an amplifier channel and the tweeter connecting to the housing on the midrange driver. If that is the case, a short to ground should activate the overcurrent protection on the amp channel and you'd lose both the midrange and tweeter. But it doesn't sound like that's what you're saying you are hearing. It's possible the short is large enough to cause you audible trouble but small enough not to activate the overcurrent protection in the amp (if it were shorting to painted metal and/or just a strand or two of wire).

Do you feel comfortable taking the door panel off (you can use the Soundstage™ instructions from our site for directions) and accessing the midrange and tweeter?

[cfm56d7b]

I suggest to call BMWNA, open a case, and mention that despite prior repair attempts the problem still persists. Insist that you suspect a short in the wiring and ask BMWNA to approve diagnostic efforts to find the short.

[smlong79]

Originally Posted by Integral Audio

Personally, I would not suspect the headunit - the HU puts out 4 channels, if you were losing one of those you'd lose the entire tweeter/mid/underseat woofer. the strange part is that it went away after they replaced the speakers. Did you experience any other long periods without trouble, similar to after they replaced the speakers?

The sound you describe does match what would happen if you had a had an intermittant chassis short on the tweeter wire. I haven't checked the wiring diagrams on the premium (I assume harman/kardon in your case?), but I believe the topology is the same as the HiFi, with the tweeter and mid sharing an amplifier channel and the tweeter connecting to the housing on the midrange driver. If that is the case, a short to ground should activate the overcurrent protection on the amp channel and you'd lose both the midrange and tweeter. But it doesn't sound like that's what you're saying you are hearing. It's possible the short is large enough to cause you audible trouble but small enough not to activate the overcurrent protection in the amp (if it were shorting to painted metal and/or just a strand or two of wire).

Do you feel comfortable taking the door panel off (you can use the Soundstage™ instructions from our site for directions) and accessing the midrange and tweeter?

Kevin - thanks for the reply and very helpful info. As I've been paying more and more attention to the issue, it appears that the tweeter and the mid-range are cutting out together. The mid-range frequencies I'm hearing, although muffled, are coming from the rear driver's side speaker which isn't too far from my ear. So yes, it's possible there's a chassis short.

When BMW checked the integrity of the wiring harness/elephant trunk running through the front pillar assembly, the problem did seem to correct itself for about a week and then resumed. To my knowledge, they've only gone into the door once - to replace the components - and it appears they didn't spend much time looking at the wires. I'm not thrilled about taking the door panel off, but yes I can do it and will take a look. Where are the crossovers located on the H/K system? Not in the door?

Thanks again for the very helpful advice.

[Kevin @ Integral Audio]

That fits the pattern better then, seems like a probably suspect. The crossovers in the HK (and HiFi for that matter) are built into the OEM amp.

Does it happen more at higher volume levels? On bumpier/rougher roads?

[Wires]

I might be ignorant to US lemon laws, but I really doubt they'd lemon a car because one A pillar tweeter sporadically works. And I'm not sure how many lawyers would be all over a giant case about the quiet tweeter.

You would be better off going directly to BMWNA to get it resolved. It does sounds like a broken wire to the amp or tweeter.

[smlong79]

The problem actually seems to be more noticeable at lower volumes...it seems that I can somewhat overcome the problem by increasing the volume, but without being able to reproduce it reliably in my driveway and listen specifically to each speaker, I can't be sure that it's not just the rear speaker volume taking over.

It does tend to be affected somewhat by bumps and/or during driving maneuvers with high lateral acceleration, which further indicates it's a physical connection/short issue. Funny though - hard/large bumps don't tend to have an effect, but smaller bumps and generally rough/etched roads do.

I ordered a new panel removal kit (lost my old one) last week and hope to get in to the door this weekend. Thanks again for all of your help.

[smlong79]

Originally Posted by Wires

I might be ignorant to US lemon laws, but I really doubt they'd lemon a car because one A pillar tweeter sporadically works. And I'm not sure how many lawyers would be all over a giant case about the quiet tweeter.

You would be better off going directly to BMWNA to get it resolved. It does sounds like a broken wire to the amp or tweeter.

Well, you might be right...but in NC to qualify as a lemon you only need demonstrate that the dealer was unable to fix the same problem after a "reasonable amount of time" and/or "reasonable amount of attempts", which turns out to be 4 or more time or greater than 20 cumulative business days. It applies to any problem that affects the use, value, or safety of the new vehicle...and while a defective left front speaker channel may not significantly affect the use or safety (although I think one could make an argument), I think you could demonstrate that a very noticeable defective audio system in a luxury automobile substantially affects its value. No?

[Wires]

It could be. Like I said, I'm completely ignorant to US lemon laws, and have no clue if something like intermittent audio would apply.

In Canada, as long as the dealership gave you something that resembles a car, then they can wipe their hands clean and we're on our own. Heck, it could be a donkey with a roundel on it's head!

[mastermoe]

Originally Posted by Wires

It could be. Like I said, I'm completely ignorant to US lemon laws, and have no clue if something like intermittent audio would apply.

In Canada, as long as the dealership gave you something that resembles a car, then they can wipe their hands clean and we're on our own. Heck, it could be a donkey with a roundel on it's head!

LOL, so true man!!