Good idea, Mike. In fact, I have the mic and have downloaded REW, but have never used it. I'd love to get your steps to proper phase. I have a hunch that that is the first thing you should set. I'm further guessing that you should measure the phase of your main speakers then match the subs to that.
I don’t set phase first. As Early B says, each speaker is done separately.
The first thing I do after determining a starting placement and toe in (by physical measurements for placement and toe in for center image) is find the crossover point. This is done one channel at a time. Turn the sub off and run a full range sweep of the LS9. You can run three or more and average them if you like. If there are any major dips you will need to move the LS9s or possibly add some diffraction. Once there are no major dips, look at the graph and find out where the LS9s are 6dB down.
Turn the amp to the LS9s off and turn the sub amp on. For the initial settings I use:
PEQ - off
Phase - 0
Crossover - pick a setting close to what you think it should be based on the previous step
Line in/ low pass - AVR/12
Rumble filter - Off
Extension Frequency - 20
Damping -High. These are just the starting points I use
Now run a sweep from 15Hz - 250Hz. If the base is significantly elevated or depressed compared to the LS9s, turn the volume up or down as needed then run another sweep. Once the average volume of the sub is close to the LS9s, determine where the sub is -6dB on the high end. You want the sub to be -6 at the same point the LS9s are -6. Adjust the crossover control in the direction you need to go and run another sweep. Continue making adjustments and running sweeps until the sub is -6 at the same frequency the LS9s are -6.
Now compare the average output of the sub with the average of the LS9s again. If the averages are not the same, adjust the sub’s volume control again until the averages are the same. Now repeat the crossover adjustment until the sub’s -6 point is the same as the LS9. Then Check the average volumes again. Keep going back and forth until both the sub and LS9 have the same average volume and -6 point. These adjustments are all with the sub. The LS9 has not been turned back on.
Next look at the sub’s graph and see if there are any peaks or valleys. If there are any valleys deal with these first as the only way to deal with them is to physically move the sub. If you have to move the sub to fix a valley, go back and recheck the average level and crossover point as necessary. If there is a peak, turn on the PEQ and start adjusting the frequency, width, and gain until you have tamed the peak.
Now turn the LS9 back on and run a full range sweep with both it and the sub playing. If the crossover point is smooth, you’re done with this speaker. If it is not smooth, start adjusting the phase on the sub until it is.
Now do all that again with the other channel. The settings on the two sub amps will likely be close but not the same.
This will get them dialed in relatively flat.
Then I turn both channels on and run a full range sweep to see what they look like together. The shape of the two channel graph is usually very close to the individual channel graphs, just 4-6dB higher.
Now listen to music for awhile then experiment with the 50/24 and 80/24 slope positions and the damping positions to determine which you like best. You can also experiment with the extension settings.
I hope all this makes sense.