Thank you but I fixed it. It was not related to a corrupt install but due to Apple design and manufacturing.
To anyone else with BT problems (stuttering, dropping connection, etc):
Bluetooth Explorer crashing when clicking Audio Tools is normal. The app is coded wrong by Apple. The AAC Bitrate slider goes out of bounds.
Run:
sudo defaults delete bluetoothaudiod "AAC Bitrate"
To get it to stop crashing when clicking Audio Tools and reset the slider back to default. ("defaults delete" merely sets it back to default)
To prevent BT stuttering and connection drops:
Run Bluetooth Explorer (from Additional Tools in Xcode 11.4)
https://developer.apple.com/download/all/?q=xcode
Set all 3 sliders to max i.e. 64, so you get:
sudo defaults read bluetoothaudiod
(enter your pasword)
{
"Apple Bitpool Max" = 63;
"Apple Bitpool Min" = 64;
"Apple Initial Bitpool" = 64;
"Enable AptX codec" = 1;
"Stream - Max Outstanding Packets" = 15;
}
And also:
defaults write com.apple.BluetoothAudioAgent "Apple Bitpool Min (editable)" -int 40
So you get:
defaults read com.apple.BluetoothAudioAgent
{
"Apple Bitpool Min (editable)" = 40;
}
Don't set them higher than 64 because you will see packet drops in BT explorer graphs.
Now: The 2.4 ghz Bluetooth in these old MBPs conflicts often with Wifi signals that are also using 2.4fgz Wifi. If you use one of these MBPs considering switching your home Wifi to 5.0ghz.
Also golden tip that few people know about:
Run RSSI Sweeper in Bluetooth Explorer from Additional Tools Xcode 11.4 (linked above). This scans the BT landscape and adjuct the packets accordingly. Scan, then click “Force Resume”.
If you move a MPB to a heavy BT congestion zone feel free to run this again prior to any heavy BT work.
Also if using Airpods to listen to music make sure the Input under sound preferences (System Settings) is not set to the Airpods microphone but is set to the internal microphone. If it is set to the Airpods mic it won't use AAC. Also set all outputs to 48khz (from 44khz) in Audio Midi Setup (Launchpad/Utilities).
You now have crystal clear audio over BT using modern airpods or a speaker and an old Macbook.
You're welcome
