2 minutes with a mic and you can have a perfectly time aligned setup. This is about as easy as it gets.
Why should you time align
Short answer: you'll get the most accurate imaging
Detailed answer: see my post on the reason time alignment is needed
What you will need
Measurement mic that will interface with DCX (ECM8000 or similar)
Step 1: equipment setup
1. Place your mic in your listening position. For this test you don't require a mic tripod, since you can probably simply place it in your couch, where your ears are when listening.
2. Connect the mic to input C on Behringer DCX
Step 2: run Auto EQ
1. Press the setup button
2. With the page button navigate to page 2 - auto align
3. Press OK
All channels will be muted. Un-mute all the channels by pressing all of them. A series of pulses will play through each channel.
4. Set gain
Rotate the dial to set the gain on DCX. If you have a preamp upstream, it will not work since DCX is acting as a source. You will need to set the volume quite high or the routine will not work.
5. Click OK
DCX will play a series of pulses and measure the time delay. It will then assign settings to align.
Step 3: review settings
1. Press channel 1 then via the page button navigate to page 7 - polarity.
You may notice the polarity of some channels has been inverted. Click through all the channels to see what has been done.
2. Review delay settings on page 8.
If you have a subwoofer included, don't be surprised if the other channels have been delayed by a large amount like 8m or 20 ms. DCX is correcting for phase shift as well, not simply the physical location of the drivers.
Why does DCX do it differently each time?
If you run the routine again, with nothing altered, you will get different settings. At first, they may appear radically different, but on closer inspection you will find the different settings are in fact doing the same thing in slightly different ways. It can correct differences with both polarity reversal and digital delay. If in a subsequent run it handles polarity differently, then it will compensate with different delay.
Confirming with measurements
You may wish to confirm with measurements. Investigate with frequency response where phase is also plotted. If you see a common 180 degrees phase shift at the crossover, DCX will simply invert polarity. If the shift isn't a neat fit, then digital delay may be used. If you know the phase shift at the crossover, you can work out the required digital delay.
First work out the time for one full cycle
Time = 1/frequency
eg. at 3k, time = 1/3000 = 0.3 ms
Delay = phase shift/180 x time for one cycle
So the delay = phase shift / 180 x 1/frequency
In this case, reversing the polarity at 3k is equivalent to 0.15 milliseconds.
Time alignment series
Why you should time align >
Is it really necessary?
Time alignment overview >
A bird's eye view of various ways that are used to time align speakers. Does physical offset really work?
Time alignment with Behringer DCX >
This is about as easy as it gets. You need a mic and a few minutes to run the auto routine.
Digital time alignment >
My preferred method. No need to build bizarre baffles that can introduce their own issues.
Subwoofer phase alignment
Yes, even subwoofers benefit, but not for the same reason