AirPods Max connection bug with non-Apple device

(I am writing this in preparation of contacting Apple Support. I am 95% sure that there is a software bug particular to AirPods Max, revealed in steps 12 to 14 below)

Preface: My goal was to find a Bluetooth transmitter to connect AirPods Max to a PowerBook G4.

Most Bluetooth transmitters have two modes – one for transmitting and one for receiving. I narrowed my purchase decision by comparing devices that have AAC in the specifications. I found that virtually all transmitters support AAC in receiving mode only. The company behind the Arylic BP50 claims that it can also send AAC over Bluetooth, so I bought it.

The "Go Control" app for the BP50 reveals the Bluetooth codec being used , which I like. It never shows AAC in transmitting mode though, which leads me to suspect that the company's claim is false. But this is not the main topic I want to address here.

I am going to describe how AirPods Max connect to this Bluetooth transmitter. I also tested with AirPods 2. AirPods 2 connect just fine, which affirms my impression that there there is a problem with AirPods Max in particular.

Preparation: On iPhone (with iOS 17.2) set "Connect to This iPhone" to "When Last Connected to This iPhone".

Step 1: Connect PowerBookk G4 with BP50. I use the digital optical output of the PowerBook to connect to the BP 50's digital optical input.

Step 2: Turn on BP50 and set it to "Optical in" mode.

Step 3: PowerBook: In Settings, confirm that audio output is "Digital out".

Step 4: Put BP50 into pairing mode. Observe that the "BT" LED is flashing to signal pairing mode.

Step 5: Remove AirPods 2 from its charging case and place them in your ears. (I had previously paired them to BP50 and would expect them to connect automatically without having to pair them again.)

Step 6: Connection to BP50 succeeds and audio plays through AirPods 2.

Step 7: Open the "Go Control" app to see that the connection is established and to see which codec is playing (SBC).

This is the flawless reference case. Once paired, AirPods 2 will connect to BP50 by request of BP50. As you would expect.

Step 8: Disconnect AirPods 2 by disconnecting them in the Go Control app. Put AirPods 2 back into the charging case.

Step 9: Remove AirPods Max from Smart Case.

Step 10: Put BP50 into pairing mode (like in step 4 above).

Step 11: Whereas AirPods 2 would react to the pairing request, AirPods Max do not, even though they have been paired to BP50 before. Following Apple's pairing guide, I press and hold the noise control button until the status light flashes white.

Step 12: Place AirPods Max on my head and notice audio in the left cup only. After ~6 seconds, there is a "snap" sound and the connection to BP50 disconnects. A clear indication that something is wrong.

After repeating steps 11 and 12 several times to confirm the bad pattern, you might want to give up and conclude that there is an issue, but there is more...

Step 13: Remove AirPods Max from my head, notice that its buttons are unresponsive for circa 10 seconds, followed but a green light, after which the buttons are responsive again.

Step 14. (I discovered this step by chance. I would normally have given up after step 12) Make sure BP50 is in pairing mode, put AirPods Max into pairing mode and once pairing is confirmed by BP50, put them on your head. As in step 12, audio from the PowerBook is only routed to the left cup.

This time, don't wait for the "snap". Within 6 seconds, open Control Center on iPhone and tap on AirPods Max, as if you wanted to connect to iPhone.

Now, here is the interesting occurence! Control Center shows AirPods Max as connected. AirPods Max however goes through some kind of calibration process, which lasts ~3 seconds, after which audio from the PowerBook sounds in both earcups. Now I have a proper connection!

This – of course, is totally counterintuitive. Why would AirPods Max adjust itself to properly connect to BP50 when requesting it to connect to iPhone? This does not make logical sense. But in practice, this is what happens and I can repeat this sequence, which means it is an unintended pattern.

I am relieved that I can get this connection established, but this is not how Apple intended it.

Step 15: Remove AirPods Max and hold it in my hands while sound continues to play from the PowerBook via BP50. After ~6 seconds, there is a hiccup and sound plays only to the left cup. I can now go into Control Center again and tap on AirPods Max. This will again initiate some kind of callibration until sounds plays okay through both cups. In Control Center, the checkmark switches back to iPhone.

Strange, isn't it? But this should be interesting for Apple developers. 👋🏻

In sum, I can connect AirPods Max, but only after a failed connection is remedied by a strange connection attempt to iPhone.

I hope someone can appreciate this report and figure out what is preventing AirPods Max to establish the same flawless connection as AirPods 2.