You can't get RT60 or decay from spatial averaging or from RTA measurements. You need to use impulse measurements. You can take a number of these, time align them, and then vector average them if you want to look at the average RT60 and Waterfall. That is a little complicated for what you are trying to do.By the way, is it best to use the center channel in conjunction with the subwoofer for the RT60 measurement ? The mic would be placed in the main listening position at ear level. Alternatively, I could take 4 readings around the listening area and average them. I guess spatial averaging enables better measurement repeatability.
Hi John, I've finally managed to get all my tools and connections in order:-