# Time Alignment



## hobst (Oct 26, 2010)

Hello Guys

I am trying to measure the distance (delay) of the Tweeters & Mid-Woofers in my car to adjust it on the miniDSP.

I already have made all the equalization for every single speaker, but now i have some trouble finding the delay times.

Can somebody tell me what is the easiest way to measure the speaker distances and phase?

Thanks a lot in advance for your much appreciated help.

Best regards, Toby


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## hobst (Oct 26, 2010)

I think i found my main problem, i didnt make the loopback connection....


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## laser188139 (Sep 19, 2009)

That would certainly do it. 

To make sense of the group delay graphs, you may need to use a fair amount of smoothing. When I took near field measures of one of my front speakers, the difference in distance to the tweeter and the midrange is obvious, but at lower frequencies variations from room effects still creep in. (I might have been able to avoid this with the impulse window.)









When I took measures from in the room at the primary listening position, the group delay graph shows a lot of variation even at 1/6 octave smoothing. 









As you can see from the first graph taken in March before REW v5, you can use the group delay even without the left channel loopback. The impulse is justified such that the nearest driver is at time zero. The left channel loopback gives you an absolute time for comparing measurements on different speakers, as in my second graph. 

Have fun,
Bill


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