Wayne Parham Messages: 18836 Registered: January 2001
Illuminati (33rd Degree)
I suspect it's cone breakup. To test that, I'd measure something else (to make sure it wasn't a measurement system anomaly) and in a different location (to make sure it wasn't introduced by the environment). That would help know that what you were seeing was caused by the speaker. Then, if so, you might do something that stiffens the cone or makes it heavier to see if the peak changes shape. If so, it's due to cone flex. You can do reversible things like using radial lines of masking tape on the cone.