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      01-15-2021, 09:43 PM   #1
Ron ///Man
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Drives: 2015 X5d 2011 335d
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Weird Audio with L7 - Need some help!

Hi All:

Having very weird audio playback where I'm missing certain portions of music tracks, like vocals on one song or certain instrumentals on another. Car is 2011 E90 with L7 audio converted by professional audio shop to Helix 8 channel and BavSound speakers and a custom sub. I'm quite perplexed and don't know how to approach this problem, and it's driving me nuts... So, the L7 goes through a D to A converter and then into the Helix. Pretty straight forward in theory. All I can say is the system sounds horrible overall. It lacks stereo imaging and mysteriously certain things are just missing on certain songs. My source is typically my iphone with songs downloaded to the phone in lossless format. If I listen to one of the subject songs through earbuds, they sound perfectly normal and I can clearly hear the missing vocals, instrumentals etc that are missing in the car. So, it's not my source. Beyond that, I'm not sure how to diagnose the issue. I unfortunately didn't own the car long before I had the audio upgraded, so I can't say with 100% certainty that this wasn't an issue with the stock setup, but, I don't believe it was. Something like this sticks out to me and I'd remember it. My gut tells me that the D to A converter might be dropping some of the signal out, but I want to believe that D to A converters have been around for decades and are pretty well engineered. My instinct tells me I should replace my head unit, but that's a pricey "guess". I'm wondering if anyone maybe has seen similar issues in the past? I read in one thread that battery voltage can cause strange issues with the audio. I haven't measured battery voltage yet, but I know the car had a brand new battery installed at the dealer just before I bought it which was in March of 2020. Can anyone with higher knowledge than mine advise and guide me? The audio shop that did the install is over 2 hours away. I took it back to them once to diagnose the problem and they weren't a whole lot of help. Said they found a bad connection into the D to A converter and fixed it. No change however after their 'fix'... Then they said the situation I describe is 'impossible' yet I proved to them it exists. I think they just don't know what to do, or want to dig into it. I'm hoping someone who knows their way around the factory system can shed some light on my issue.

2015 X5 35d
2011 335d M Sport
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      01-16-2021, 12:02 PM   #2
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Drives: 325xi 06 wagon MT
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iphone connected how to what type of head unit?
Aux connection wireless connection?
If you play high quality audio through other sources
how does it sound on the radio or cd?
How is it wired?
Do you have the ability to tune it yourself?
What is the reputation of the shop you took it to?
If you went to a bass head shop maybe they tuned everything out but the bass.
What is the exact Head unit and Most Converter?
If things where working before this conversion I would not start out
by replacing known to work parts.

When you say D/A converter do you mean Most to analog converter?

There is a 14 part series on ytube on how to tune a Helix DSP.

Last edited by ctuna; 01-16-2021 at 12:07 PM..
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