[brucemck2]

I use a DEQX to PEQ my front two speakers and to perform crossover duties between my L/R mains and subs. I use REQ to determine PEQ settings.

The extra digital processing inserts a LOT of incremental time delays (could be 38ms) for my fronts and subs that all the rest of my speakers don't incur (a Center and four surrounds don't go through those delays.)

I'm wondering if I can use REQ to time align my Center and surrounds with the mains, and, to confirm time alignment between my subs and L/R mains? I figured I could take a measurement of each speaker, individually, and use the time differentials measured to compute effective distance differentials.

As I understand it the place to look is the time vs. energy chart. When I eyeball charts I see a "steady decline" from the initial peak/impulse down to around 3ms, then the chart "levels off" from a steep vertical to a more horizontal slope, and, begins to "wiggle" or "modulate" up and down quite a bit.

I assume the point in time at which that transition occurs is the "time gap"? ... that if I calculated that point for each speaker then the differences would be the effective distance differentials for each speaker (eg, if one speaker were at 6ms and another at 2ms then the first speaker was 4ms further away than the second speaker?

A related question. When run full range my surrounds have very little energy below 60hz, so I suppose to get this right I'd have to begin the measurement of all channels at a frequency high enough that all speakers would be "active"? That is, I assume the time vs. energy chart "begins" at the low frequency beginning of the sweeps?