Pretty happy with my test setup, sans $250K anechoic chamber. I ended up just opening my garage door and facing the speaker down the driveway, just placed outside the garage door opening. This meant I didn't have to drag everything out to my yard, and the results were 100% better than indoor testing which was basically useless, other than seeing how colored the environment is. The data:
The low frequency dips at 120Hz, 350Hz and 700Hz are resonances due to the test setup, so those can be ignored. They appear in my Fostex speaker, too. You can see that the low frequency -3dB cut off is around 70Hz, and that is indeed the spec for this speaker. Above 4kHz, we have a rising output due to a mismatch between the tweeter and woofer. The stock crossover has a 10W 1.5 ohm resistor that could've been larger. It's not horrible, but I think this explains why this speaker's tweeter is referred to as harsh by many listeners - it just slightly overpowers everything else. Finally, note that I'm not using a calibrated, lab grade mic, but a RS SPL Digital meter (with inverse C weighted transfer function). But I think my sweep is pretty close to reality and makes sense to me. I'll post my Fostex speaker for comparison:
The two low freq dips are exactly the same as the Infinity, so I am confident it is my imperfect test setup. The flatter response between 4kHz and 10kHz seems correct to me, and leads me to believe that the Infinity sweep isn't faulty in the same region.
I was pretty happy with this sweep. My -3dB cutoff is around 80Hz, and I have fairly flat response for this design - I expected much worse resonances. I think it is obvious I need to add a tweeter to this speaker - just a simple cap coupled tweet and no other crossover components.
Shannon