Question about Damping, Leakage and Port Q

[philiprst]

I am using Speaker workshop to help design my first "from the ground up" project; a 2 cu. ft. vented enclosure with a single 3" port.

I have just measured the impedance of the prototype enclosure+driver. The two impedance peaks are in roughly the right place and the box frequency is within 1Hz of where it should be for the alignment I chose. However, the width of the impedance peaks in the measured curve is significantly bigger that the calculated impedance and the peak heights did not agree very well.

I assume that this discrepancy has something to do with the choice of Q values in the model not matching the actual Q values for the real enclosure. I have started by using the SW default values of: Leakage Q =7 and Port/Damping Q=100. Can someone please help and tell me how to estimate these values for a real enclosure? The enclosure is heavily braced 3/4" MDF with 1" baffles with (at the moment) about 30% dacron polyfill stuffing. Is it possible to derive any of these Q values directly from the measured impedance curve?

Philip