Referencing For Time-Alignment

[M49]

Dear REW Folks,
When I use the Acoustic Timing Reference, Impulse Response measurements from different distances are all normalized to 0.00ms--no matter the distance. When I use Loopback as reference, I do see the timing differences. But all the guidance instructs using Acoustic Timing Reference--and that makes sense, except that everything gets normalized to zero. What's going on here?

 

[sm52]

This screenshot shows four drivers measured with Acoustic Timing Reference.

 

[John Mulcahy]

When you use the acoustic timing reference times are relative to the arrival of the acoustic reference at the microphone, so the travel time from reference speaker to mic is automatically removed. When you use a loopback you need to remove that travel time manually, which you can do using the timing offset entry on the Measure dialog.