I am not really experienced with Arduino within the field of Bluetooth or audio. For a project I need to play several audio files on different devices (phones can be used for this) at the same time. So when I click on the audio file I want it to be played on the same time on each device. I will probably use 4 or 5 devices at the same time. The number of audio files will probably be 20 and up.
If you know how I can do it with Bluetooth (or on a different way), please let me know
Bluetooth 5 allows sending audio to TWO devices, but that's not what you're after.
Bluetooth is a secure way to connect one transmitter to one receiver, so what you're looking to do isn't really possible... it's not like radio waves that any receiver can pick up.
If you really need to use Bluetooth to do this, you're going to want to get multiple Bluetooth audio transmitters so each receiving device (headphones, speaker, etc) can pair to one Bluetooth transmitting device. They're less than $5 from Aliexpress, the kind you plug in to a USB port and plug in an audio aux cable. You'll need lots of aux cable splitters too!
Thanks for your reply. I have found a way to do it (but I will not prototype it myself). I will make use of Walkie Talkies (transceiver) and use radio waves!
