Humps at 43Hz, 90Hz, and 110Hz

[RickyV]

Frequencies under 200 Hz are difficult to measure in a normal room because off all the reflections. Even Nearfield measurements, say 50cm from the woofer cone are not very trustworthy.

Even in a room like this where I did my final measurements of my speakers, every thing under 100Hz is difficult.

 

If you measure several times see if you get the same plot more or less. If you do that over the whole spectrum you can see where it starts to get unstable.