misconceptions about impedence rise

[helotaxi 5,000+ posts]

It's purely a factor of the enclosure. The air in the port is most excited at resonance. It is also perfectly in sync with the cone at that point. The whole tuning equation calculates the port length and size that equates to a 180deg phase delay at the mouth of the port relative to the rear wave of the driver. Because of this phase delay the driver is also attempting to overcome the inertia of the air in the port. The port inertia exercises maximum cone control at this point and makes sure that the cone moves the least here. IIRC capacitive reactance is the main component of impedance at this point in the curve. As frequency increases, the inductance increases.

Final thing, in you original post, I missed this before, resistance is constant with frequency and does not have a phase. The current flowing in the system is out of phase with the voltage because of phase lag from inductance.

 

[nineballsafety8 10+ year member]

thanks taxi... thats some good information. whats your backgroung in the biz... you sound like you have a fairly good grasp

 

[helotaxi 5,000+ posts]

Just a hobbyist for the last 17 years. College degree in Econ that involved more engineering classes than econ ones. Two trips to the desert under my belt as well. Headed that way again in a couple weeks.

 

[nineballsafety8 10+ year member]

u know where you're going?

 

[helotaxi 5,000+ posts]

Afghanistan. Spent a few months at LSA Anaconda/Balad AB about 2 years ago and a few months at the CAOC about 2 years before that.

 

[audioarsonal 10+ year member]

Your knowledge will be missed....//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[helotaxi 5,000+ posts]

I'll still be online.

 

[audioarsonal 10+ year member]

//content.invisioncic.com/y282845/emoticons/woot.gif.aaa6090e619a97b6090d16dd863c5a69.gif

 

[nineballsafety8 10+ year member]

stay safe and rake in that dough... my wife is headed to Balad in March.