Originally Posted by weltersys
If you place the microphone very close to the ground outdoors, well away from large objects and buildings, you eliminate floor reflections applicable to low frequencies. I use a windscreen for all outdoor measurements, and simply lay the microphone down on a 1/2 meter square piece of plywood, usually at around two meters from the sub.
I'd measure further away, but various buildings are all around my test area, if I measure at 10 meters they affect the response.
As far as test tones, if you don't have a sine wave tone generator you can down load sine wave tones for playback. For a 2 meter test, set the output of your amplifier to 5.66 volts at 60 Hz, then leave the output the same as you test at different frequencies.
Your dB meter should be set to "flat" or "C" if there is no flat setting. The "C" setting will roll off the response slightly in the bottom end, about -2 at 40 Hz and -6 at 20 Hz.
Make sure that wind noise (and other ambient noise) is not part of your reading, a steady wind can show up as a fairly high dB reading, especially with no wind screen.
Higher drive levels will make for a better signal to noise ratio.
Even with a wind screen, I spend more than half my measurement time waiting for gusts to die down.
Good luck, hopefully the chamber results are not indicative of your cabinet's response.
i'll keep you informed.
Thanks for a loooot all your help!