# REW measurements, subwoofer phase?



## lillgunde (Dec 10, 2010)

Hey everybody.

Took a couple of measurements of my subwoofer using REW, and I am trying to determine if the subwoofer
is in phase with my front speakers.

I have checked the polarity of the speakers so they are wired correctly, but I don´t know if I should run the
subwoofer at "0" or "-180" phase.

http://www.minhembio.com/bilder/bild/?pic_id=458817.jpg

Is the above image enough to read out the phase?


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## Wayne A. Pflughaupt (Apr 13, 2006)

We’d have to see a full-range measurement (main speaker + sub) to see if there are any phase issues. It would show up in the frequency response in the region of the crossover frequency. I’d measure at 0 and 180 and see which one looks best.

By the way, welcome to the Forum!

Regards, 
Wayne


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## lillgunde (Dec 10, 2010)

Thanks for your answer Wayne.
I have done a lot of measuring this week to get my Minidsp up and running.
I am still a little confused about the phase response since my pioneer receiver has some 
crazy phase function so I am trying to stick with the phase of the subwoofer at 0.

I am wondering about the "Estiamte IR Delay" function that REW has though???
Left, Center and Right has an estimated IR Delay of -0,0035ms, a discrepancy at the most.
But the subwoofer has an estimated IR Delay of -10,954ms (-12,33ft)....?

Is this a correction that I can add to the subwoofer to get all of the speakers to play/be more
in sync with eachother and thereby get a little more out of my setup...? Or something else??


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## JohnM (Apr 11, 2006)

lillgunde said:


> I am wondering about the "Estimate IR Delay" function that REW has though???


That function is mainly aimed at arriving at an appropriate zero time setting for the measurement, it is not useful for relative timing of speakers. For that you need to have a loopback connection to provide REW with a timing reference signal and to look at the differences in the system delay figures REW then produces (as shown in the info panel for measurements made with a timing reference loopback connection).


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