For those thinking about measuring outside, for practical reasons I don't do it. The last DEQX calibration that I was involved was with a pair Apogee Full Range and at 300 pounds each they ain't going anywhere! Measuring outside lengthens the time it takes for the calibration microphone to hear the first reflection. Longer the time until the first reflection, the lower in frequency your calibration will be accurate. Recently, after talking with Nyal Mellor of Acoustic Frontiers, I normally don't try to correct anything below 500 or 600HZ anymore. I seem to get better results now rather than trying to correct all the way down to 250 to 300 Hz or so which is usually where the first reflection places its limit on lower-end calibration when measured indoors.
Normally when I do a DEQX calibration indoors, I move the each speaker (if movable) one at a time to the center of the room and perform a measurement then move it back. I also toss some blankets of the floor between the microphone and the speaker to be measured, then perform the measurement. The first reflection usually comes from the floor or ceiling.
What I saying is that by not measuring the speakers outdoors is by no means a deal breaker. You can get great result measuring indoors. Just use the Earthworks M23 or M30 calibration mic. If you have large speakers with large ribbon drivers or large array like Apogees, you will probably find that you will get the best results if you measure the speakers anywhere from 5- to 7-feet back rather than the recommended 3-feet.
