Difference Vector Average and RMS + Phase

[pklose]

I am confused: What is the diiference between Vector average and RMS + Phase average? Everytime I try it out, I get the same results with the methods. The manual does not really help me. Can someone please explain?

 

[John Mulcahy]

In vector average the magnitude response depends on the relative phases of the signals being averaged. In RMS + phase average it doesn't.

 

[pklose]

I cannot think of a situation where on is more useful than the other.

 

[moedra]

I seem to recall that there was a way to check for phase issues between channels (where they are out of phase with each other) from the LP by comparing some of the averages together. I can't remember exactly what to do to get the result I want, though. I do know that the mic remains stationary and that the left and right speakers are measured once each.

I think it was something like this:

- Average the left and right channels together using one of the dB or SPL averages (again, can't remember which)
- Create a vector average of the left and right channels
- Compare the two averages on the All SPL page, looking for areas where they deviate.

Maybe there was an operation to execute on the averages... memory fails me.

What looks right to me is comparing the vector average to the dB average, but I'm not sure. Perhaps the answer is to compare a vector average derived from the measured L and R responses to a vector average derived from minimum phase copies of the L and R responses. I'm just not sure what combination is actually telling me what I want to know, which is, at which frequencies in the spectrum the speakers are in phase with each other, and where they are out of phase with each other.

Perhaps John can enlighten me. I think that this would be a useful thing to see. If there's a way we can visualize phase issues at specific frequencies, would it be possible to use that information to help with room treatment decisions?

 

[John Mulcahy]

Comparing the vector and RMS averages would achieve that, or look at the overlay phase responses.