The importance of Kms(X) and BL(x) for mid-ranges

Hello All,

Sitting here on my bench is a GRAS 46B-1 1/4 inch microphone.

A fun fact, microphones are calibrated in SPL per Pascal. Microphones are pressure sensors.

A driver in a sealed enclosure operates with with the additional stiffness of air suspension. The air pressure can be measured with a in box microphone. All of this is knowable and measurable. The in box air pressure will effect the position of the voice coil in the motor flux field.

Now I am visualizing what will happen to the in box air pressure in a enclosure fitted with a passive radiator. An interesting thing is that the PR will have a much longer excursion than the the driver Voice Coil. The in box air pressure will modulate differently than in a sealed enclosure speaker.

Thanks DT

I will make some measurements with the sealed box. Impedance, Frequency Response sweeps, HD and IMD. Thoughts?

Later with the Passive Radiator.
 
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