A useful measurement needs little equipment: a measurement microphone, an interface and swept-sine software. The microphone need not be expensive, but it must come with its calibration file.
Indoors, reflections corrupt everything below roughly 300 Hz. Time windowing removes them: the impulse response is truncated before the first reflection arrives, at the cost of limited resolution in the bass.
For the bass itself, a near-field measurement with the microphone almost touching the cone gives a usable result, which is then spliced to the far-field curve.
Impedance measurement usefully complements the acoustic one. It reveals the real cabinet tuning, the driver resonance after mounting and any air leaks, which are invisible otherwise.
Comparing the impedance curve before and after filling the cabinet shows the effect of damping immediately: the peaks round off and shift slightly downwards.
Measure at the distance you will listen from, on the axis you will listen on. A curve taken at one metre on the tweeter axis describes a condition nobody experiences; at two or three metres the drivers sum as they actually will.
Keep the raw files. A measurement is only useful against another measurement, and the comparison that answers most questions is the one between this attempt and the previous one.
