Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
That looks like a measurement made indoors. We're seeing room modes and self-interference. The dips around 100Hz to 150Hz look like self-interference from the nearest boundary, which are precisely what flanking subs correct.
You'll notice your first measurement shows this dip too, which was probably also an indoor measurement. But in your first measurement, the microphone rolls off heavily under 100Hz, so we don't see any output below the notches. It looks like sharp rolloff below 150Hz but that's just because you can't see the output below the 100-150Hz self-interference notches.
I'd say the speakers are fine, and probably what you want to do is to add flanking subs to mitigate the self-interference anomaly. It's pretty normal, and all speakers suffer from that because it's a room issue, not a loudspeaker issue.