What's wrong with bluetooth measurements ?

Hello, I am doing some tests on loudspeaker having a bluetooth and a RCA entry.

I use the USB wired UMIK-1 to record.

I was really surprised to see the differences in IR for 2 sweep measurments, one driven by RCA wires (and soundcard of the PC) and the second driven by bluetooth :


(RCA)


(Bluetooth)


Same setup, same sweep, same level on the computer, software and loudspeaker...

But there is an ugly response with bluetooth, with this big bounces before what seems to be the IR peak...

Also, we can hear and observe that the sound level is a bit smaller with bluetooth (I don't know why neither)

Then, I have 3 questions :

1 - is this behaviour common, or pathological and caused by a problem in the bluetooth transmission ?
2 - is there an explanation for the differences (especially for the bluetooth response, as the RCA response seems "normal") and a way to have clean bluetooth measurements ? (As most people will use bluetooth)
3 - the music rendering on bluetooth is still satisfying, but should I expect an altered rendering because of this IR ? Or is it more a REW artifact ?

Thank you for your help !

Thank you, I'll try it next time

So there isn't such a difference in sound during a regular use ?