REW measurement issue

[Stef Smits]

Hello,

For some 3-way boxes I have to make a preset from scratch because of the new components, however when measuring I get an uncorrect phase response.
Obviousely I am doing something wrong but I cant see (the simple) error that I make.

Setup is as follows:
-Focusrite scarlett 2i2
-Behringer ECM8000

ECM8000--> channel 1
2i2 right out -->2i2 channel 2 in (loopback)
2i2 left out to mixer--> DSP and amps

48V turned on for ECM8000, channel 1/2--> Line, Direct monitor = Off


In the attached file, you can see the phase response that I am getting.

 

[John Mulcahy]

You are probably seeing the time of flight delay from speaker to mic, plus any processing delay in the DSP, since the t=0 point is set by the loopback which isn't subject to those delays. You can allow for that in the "Timing offset" field on the Measure dialog. If you use the "Estimate IR delay" feature in the graph controls REW will estimate that figure for you and enter it on the dialog.