High freq noise through bluetooth stereo?

[Earl42]

Just bought a pioneer deh-p7900bt head unit for my truck. When I play music through the bluetooth there seems to be some noise/destortion/tininess in the upper range. Is this normal for bluetooth? I have tried many of the bluetooth tweaks but to no avail. Anyone else have this problem? Any suggestions?

[dishe]

there's a lot of bogus / outdated tweaks floating around the net for BT audio. The A2DP support in WM5 was very poor, and some crazy registry settings claimed to alleviate the problem.

Since WM6, the optimal settings are very different, so you have to make sure you haven't been following an older set of tweaks.
Here's the current recommended settings:

REMOVE ALL ENTRIES AT HKLM\Software\Microsoft\Bluetooth\A2DP\Settings

Except for this one:
UseJointStereo = 1

THIS IS THE ONLY NECESSARY SETTING FOR GOOD A2DP. What this does is enable Joint-Stereo for the SBC codec, which is important and makes the biggest significant change to improve sound quality. (Note: In earlier versions of WM5 and WM6, Joint-Stereo was broken and resulted in a mono-output. This is not the case anymore with the newer WM6 ROMS.)

Delete the bitpool settings! I can't stress this enough! they serve to limit the amount of bandwidth/CPU time dedicated to encoding the audio, which results in lower-quality sound, but frees up system resources for other tasks. This was necessary on slower CPUs (like the 200mhz omap), but you don't need it and all it will do is lower the quality.

For audiophiles, you can also optionally set:
Name: SampleRate
Value (DWORD): 48000 (decimal)

Default is 44000. This shouldn't make a great deal of difference, but trained ears might be able to tell. To be quite honest, I prefer the sound of 44000 often because it has a more forward-clarity. For complex instrumentals, 48000 will give wider range I think.

If you do this right, and have a decent stereo receiver, bluetooth audio can sound as good as wired headphones. I've plugged saunheisser earbuds into an a2dp receiver, and had audiophile friends swear they can't tell the difference.

[NissanGuy01]

Originally Posted by dishe

......For audiophiles, you can also optionally set:
Name: SampleRate
Value (DWORD): 48000 (decimal)...

Where do you change the samplerate reg key at? I didnt see it anywhere under blueteeth or under the a2dp settings.

[Earl42]

Where do you change the samplerate reg key at? I didnt see it anywhere under blueteeth or under the a2dp settings.

HKLM\Software\Microsoft\Bluetooth\A2DP\Settings
add new DWORD
name: SampleRate
Value: 48000 (decimal)

THANK YOU DISHE!

That worked perfectly, no more buzz or upper end distortion.

[dishe]

Originally Posted by Earl42

HKLM\Software\Microsoft\Bluetooth\A2DP\Settings
add new DWORD
name: SampleRate
Value: 48000 (decimal)

THANK YOU DISHE!

That worked perfectly, no more buzz or upper end distortion.

No prob. Glad I could help another a2dp car stereo listener!

Lot of people still don't believe BT can transport good sound...

[luv2drum]

You also helped me! Thanks for the info. I'm sending audio from my Mogul to my Pioneer 7900BT with now great results!! XM who???

[Brett8187]

if it doesnt work search my posts ( i have like 2) i posted up a bluetooth fix to that exact thing i think a different way

[luv2drum]

Thanks! I have found the reg tweak above fixed the poor audio I had. Now I can stream Radioio.com or sky.fm to my Mogul then to my radio with great audio quality! I had my Pioneer DEH-7900BT before I got my Mogul and had only used it with my Treo 755p. Now I'm really glad I upgraded to the Mogul!!