Phase Alignment versus Time Alignment

[Dan Twomey]

I just recently watched a video that covered REWs alignment tool and they used it to align the phases of the
subwoofer and speaker woofer at the crossover point. I found this quite interesting but it made me also think of
driver time alignment where you use (I have a two-way active system) the acoustic timing reference to
time align the drivers.

Thoughts anyone?

Regards,
Dan

 

[Keith_W]

Please read Bob McCarthy's article on phase and time alignment.

In a nutshell, the goal of phase/time alignment is to (1) get rid of egregious delays, and (2) remove nulls at the XO point as much as possible. So you have to do both - time align first, then phase align.

Look at it this way: Take two identical sine waves. If one is 180deg out of phase with the other, it will perfectly cancel. It will be the same at 540deg (180 + 360). The only difference is that the second sine wave is delayed by 1 period. If all you did was to shift the phase by 180deg, you would still be left with a delay of 1 period. At 80Hz, one period is 12.5ms. It's probably marginally audible but it's still better not to have that delay in the first place. So you have to time align first to bring the two speakers roughly into alignment, then use the alignment tool's fine delay adjustment to remove the nulls as much as possible.

 

[Dan Twomey]

I have a basic understanding of phase misalignment.

Many thanks for the link to the article.

Regards,
Dan