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I have read quite a few threads in this forum and have not come across the thread I need, I hope someone here can help me.

I am new to using REW. I recently started experimenting with a mini DSP 2 x 4 to make an active crossover for an old pair of Klipsch speakers that I have. In the process of learning to create a crossover I came across the importance of time aligning the speakers. MiniDSP recommends using REW with a loop back to accurately measure the time taken for the sound to travel from speaker to the measurement mic. My understanding is that I can measure that time for my woofer and then measure the time for my tweeter subtract the two measurements and then use the difference as my alignment in my miniDSP.

I have the REW software. I am using the software on a MacBook. I have successfully installed and calibrated an ART Dual Pre And Dayton audio measurement microphone. I have a loopback cable in place with the dual pre from right input to right output. I made a calibration file for the Dual Pre and have the correction file for the mic. I have my preferences set under Analysis tab to use loopback. I have unselected the checkbox setting for Set T=0 at IR Peak.

My measurements seem to still be setting at 0 at the peak of the impulse response. Am I doing something wrong? Where should I be looking for the timing measurement information? I could really use some help in identifying this time delay information in REW.

Thank you for your help in advance.
 

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This sounds correct. Just some thoughts:

I have my preferences set under Analysis tab to use loopback. I have unselected the checkbox setting for Set T=0 at IR Peak.
In the latest REW version that I am using (latest beta version) that check box is disabled when 'Use loopback for timing reference' is selected. It will have no impact on the result.

My measurements seem to still be setting at 0 at the peak of the impulse response... Where should I be looking for the timing measurement information?
> Review the channel selections in 'Preferences/Soundcard'.

> Did you zoom out enough on the ms scale of the 'Impulse' graph to be sure where the IR is located? There may be a small IR tick at 0ms due to internal crosstalk with some soundcards. This should be ignored.

> You may want view and review the Info popup for the measurements and see if loopback was applied.

> If there is still a problem, I suggest you post an .mdat file containing a measurement of the horn and of the woofer. There is maybe a hint of the issue in the file.
 
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