Problems with music over Bluetooth
November 29, 2011 8:08 AM   Subscribe

I'm having problems playing music in my car from my iPhone via Bluetooth.

I just got a new car that has Bluetooth. For the most part, playing music from my iPhone 4 (running iOS 5.0.1) via Bluetooth is great. However, there are some albums that completely cut out some of the channels in the songs. For example, listening to Giant Steps by Coltrane this morning, the lead horn sounded far away than the rest of the band, like it was down the hall and in a different room (metaphorically speaking).

I've noticed this on several other albums. It seems like it's mostly 60's-era music that I ripped from CD instead of buying online. I've looked for settings on my phone (both iTunes and Bluetooth) as well as my car stereo, and can't find anything that seems to solve this problem. Am I missing something, or is there something wrong with the music files that I'm trying to play?
posted by slogger to Technology (8 answers total) 2 users marked this as a favorite
 
The 'vintage music' note is telling; in the early days of stereo recording they'd often mix the lead or specific accompanists almost completely to one channel only. The idea was to sound like they were in one corner of your room when playing over speakers.

For example, on a Coltrane track I have, he's almost exclusively in the left channel. I find this almost unlistenable from my iPhone 4 5.0.1 on my Bluetooth headphones, for example, but I can confirm that those headphones do at least deliver both stereo channels, and it sounds like your car isn't.

At the risk of sounding condescending, I'd check the L/R balance of your car speakers, and also verify they're each producing at similar levels when balanced with modern tracks that are mixed more moderately. If it's still whacked after that, then perhaps your car Bluetooth receiver only pulls one channel? Maybe it has a wiring issue? Only guessing on that.
posted by BlackPebble at 9:27 AM on November 29, 2011


I should also mention I once had problems playing vintage tracks on my previous iPhone through a dock. I found the left-channel pin in the 30-pin connector port was bent and not making contact, so only the right channel was coming through. Sounded just like your soloist down a long hallway.
posted by BlackPebble at 9:29 AM on November 29, 2011


I think BlackPebble is likely on-point here. Does this car stereo also have a 1/8" jack input so you can compare the same song and same playback system and only change the transmission medium?

There's no reason I'm aware of that the bluetooth should be notably different from listening via headphones or using a dock connector. The only way I could imagine a difference would be if the bluetooth transmission bypasses the decoder. I remember people whining about the decoding in iPods back in the day; its' possible your car stereo's decoding is defective in some way but that seems questionable.

Testsounds.com has some audio files that sweep around the frequencies and channels. Try loading some on your phone and playing them back both via the built-in speaker and the bluetooth. If you have major missing sections then you know it's a car hardware problem.
posted by phearlez at 9:59 AM on November 29, 2011


Thanks BlackPebble and phearlez. I just went out to the car during lunch. The music sounds find over the 1/8" jack and dock connector. It's only over the Bluetooth where the channels are cut out. I downloaded a couple of tracks from testsounds.com and played them over both the Bluetooth, dock connector and the 1/8", and sure enough, the left channel test track isn't audible over Bluetooth, but works fine over the dock connector and 1/8". Looks like it's back to the dealership for me *sigh*
posted by slogger at 11:13 AM on November 29, 2011


You don't say what kind of car you have, but is it possible that your car doesn't use the Bluetooth A2DP profile needed for stereo streaming?
posted by FreezBoy at 11:37 AM on November 29, 2011


Freezboy: It's a 2012 VW Jetta Sportwagon. I'm trying to Google whether the "Touchscreen Premium VIII sound system" has A2DP, by my Google-fu is failing me.
posted by slogger at 11:50 AM on November 29, 2011


I am reasonably certain that there was not a mono bluetooth profile defined, but I would be shocked if there was one that didn't collapse the channels into one rather than just dumping one.

It seems far more likely that you have a radio where there's a bad solder joint in the radio on one of the pins coming off the bluetooth decoder chip. Or so I'd hope - the alternative is there's a manufacturing flaw and ALL the radios are dicked up. However you can test this pretty easily by having them let you try your phone in another car on the lot with the same sound system.
posted by phearlez at 12:48 PM on November 29, 2011


I just took my car to the dealer and had it checked out. They tested it through different phones on my car, and with my phone on different cars. They reproduced the effect on other cars with the same stereo, so it looks like it's a design flaw with the VW stereos. Hard to believe I'm the first person to uncover this flaw, but there it is. Thanks to all for the help!
posted by slogger at 7:08 AM on November 30, 2011


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