This discussion has been locked.

You can no longer post new replies to this discussion. If you have a question you can start a new discussion

BMW Navigator IV / Zumo 660: Very poor bluetooth stereo headset sound

Former Member over 13 years ago

Hello,

I recently purchased a BMW Navigator IV (rebranded Garmin 660) and am experiencing an intolerable Bluetooth stereo (A2DP) sound quality issue. High-frequency sounds are "smudged" in transmission over the bluetooth connection, resulting in a fairly obnoxious static-like or scratching sound delivered through the headset. The unit is running the latest available software (as of June 12, 2011), i.e., version 4.20.

The issue is most prominent on certain tracks. One track that I'll use as an example "Subdivisions" from Rush's "Signals" album. The issue is not unique to this track, it just works well as a test case as the problem is apparent very early in this song.

The track sounds as expected when listening to it with a set of headphones plugged directly into the unit's 3.5mm jack. Listening with the same set of headphones plugged into a Sony Ericsson MW600 bluetooth headset results in very poor sound quality. (NOTE: this stereo bluetooth headset is designed to accept any set of headphones, for this test I used the set of headphones which were included with it).

I tried playing around with MP3 encoding to see if there was any correlation with it. I started with an uncompressed (WAV) copy of the track "Subdivisions." I tried encoding at 64, 96, 128, 192, 256, and 320kbps constant bit rate, and a few variable bit rate settings using the popular LAME encoder. I also tried encoding MP3s using iTunes (Mac) with both default and best-quality settings. In all cases I started with a CD quality WAV file. None of the encoding settings had any effect on the issue.

I've tried reducing the volume on the unit and/or the headset. The artifacts are still present at the same level as the music itself.

I've tried two different Bluetooth headsets. The first is a Motorola S9-HD and the second is a Sony Ericsson MW600. Both exhibit the problem. The problem does not occur with these headsets (and the same track) when they are paired to other devices, such as Motorola Droid X and/or Droid 2 phones.

I've tried disabling and unpairing all other devices. I've tried resetting all Bluetooth settings. I've tried re-applying the 4.20 update. I've tried resetting the device (hold lower-right corner on boot, erase all data). No effect.

From what I understand about Bluetooth, audio is recompressed and digitally transmitted from a music player to a stereo headset at a bitrate agreed upon by both headset and music-playing-device. Devices can specify a minimum required bitrate. I believe this minimum bitrate value is too low on the Garmin Zumo 660/BMW Nav IV, and must be increased in order for the device to transmit music at an acceptable quality.

I'd greatly appreciate any advice, workarounds, hacks, suggestions of specific Bluetooth headsets which work well, etc.

Best
--Tod

0 Tony_Worrall over 13 years ago

Hello,

I recently purchased a BMW Navigator IV (rebranded Garmin 660) and am experiencing an intolerable Bluetooth stereo (A2DP) sound quality issue. High-frequency sounds are "smudged" in transmission over the bluetooth connection, resulting in a fairly obnoxious static-like or scratching sound delivered through the headset. The unit is running the latest available software (as of June 12, 2011), i.e., version 4.20.

The issue is most prominent on certain tracks. One track that I'll use as an example "Subdivisions" from Rush's "Signals" album. The issue is not unique to this track, it just works well as a test case as the problem is apparent very early in this song.

The track sounds as expected when listening to it with a set of headphones plugged directly into the unit's 3.5mm jack. Listening with the same set of headphones plugged into a Sony Ericsson MW600 bluetooth headset results in very poor sound quality. (NOTE: this stereo bluetooth headset is designed to accept any set of headphones, for this test I used the set of headphones which were included with it).

I tried playing around with MP3 encoding to see if there was any correlation with it. I started with an uncompressed (WAV) copy of the track "Subdivisions." I tried encoding at 64, 96, 128, 192, 256, and 320kbps constant bit rate, and a few variable bit rate settings using the popular LAME encoder. I also tried encoding MP3s using iTunes (Mac) with both default and best-quality settings. In all cases I started with a CD quality WAV file. None of the encoding settings had any effect on the issue.

I've tried reducing the volume on the unit and/or the headset. The artifacts are still present at the same level as the music itself.

I've tried two different Bluetooth headsets. The first is a Motorola S9-HD and the second is a Sony Ericsson MW600. Both exhibit the problem. The problem does not occur with these headsets (and the same track) when they are paired to other devices, such as Motorola Droid X and/or Droid 2 phones.

I've tried disabling and unpairing all other devices. I've tried resetting all Bluetooth settings. I've tried re-applying the 4.20 update. I've tried resetting the device (hold lower-right corner on boot, erase all data). No effect.

From what I understand about Bluetooth, audio is recompressed and digitally transmitted from a music player to a stereo headset at a bitrate agreed upon by both headset and music-playing-device. Devices can specify a minimum required bitrate. I believe this minimum bitrate value is too low on the Garmin Zumo 660/BMW Nav IV, and must be increased in order for the device to transmit music at an acceptable quality.

I'd greatly appreciate any advice, workarounds, hacks, suggestions of specific Bluetooth headsets which work well, etc.

Best
--Tod

I concur with everything you have written. The mp3 reproduction via the BT connection is not much better than Eddisons 1st attempt using a wax cylinder.
My only solution was to hard wire the 550 to my Starcom1 intercom via an audio cable. Unfortunately this means that I have to connect my phone via the BT dongle (BTM-02) on my Starcom1 - ok for receiving calls but you cannot use the 550s address book for making calls.
I think this is a poor solution but it does give you good quality music from the 550.