DAC in streaming over bluetooth

[dheqwu]

Hi,

I'm wrapping my head around sound reproduction, and I can't find for the life of me an answer to this question: when the source is digital, streamed or stored, and listened through bluetooth, does the source device matter? It seems to me that the only digital to analogue conversion happens in the bluetooth receiver, and everything before that is digital.

So, if I stream through an app on the phone a file of a certain quality, is that file transferred as is to the bluetooth receiver, which is then entirely responsible of the quality of the reproduction, or does the transmitter do any re-encoding of the file? The follow up question then naturally is: should I invest in a music player or in better bluetooth headphones?

Thanks a lot!

 

[Vincent Kars]

does the transmitter do any re-encoding of the file?

It always do.
Basically your media player reads the audio file being WAV, FLAC, MP3, AAC, wat ever format supported and decode this to PCM. This is send to the Bluetooth sender. There it is compressed using the codec negotiated between sender and sink e,g, SBC, APTX, AAC, LDAC, etc.
This is lossy compression because of the limited bandwidth available for BT audio.
The receiver decodes it back to PCM. This is send to the DAC of the headphone and the output is amplified by the headphone amp.

Bit more detail: https://www.thewelltemperedcomputer.com/HW/Bluetooth.htm

 

[dheqwu]

thank you, very interesting.

So, would you say that the transmitter has the same role as a preamp, or does it matter less in the final sound? Thanks again!

 

[Vincent Kars]

transmitter has the same role as a preamp

No, it has the same role as MP3, saving bandwidth by applying lossy compression.