Impedance correction at a compression driver's Fs - How to calculate - Wayne P?

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Posted by Peter K [ 130.225.37.97 ] on March 21, 2006 at 05:13:57:

Hello!

I have a pair of 2” BMS 4592 ND (16 Ohm version) coax compression drivers on their way to be used from about 300 Hz and up on a large 200 Hz exponential horn for my home system.

I would like to make an impedance correction curcuit to flatten-out the impedance peak around the Fs of the BMD "mid-section" (app. 360 Hz according to the graphs on the BMS website). There is a link to the driver below.

Besides, I have from the manufacturer (BMS) got the following values for the 16 Ohm version:

Re (mid) = 8.9
Le= 0.19 (at 10 kHz)


If I understand it correctly, an impedance corrections curcuit (Zobel?) can be calculated quite precise when the driver’s Qes and Qms are available. But that is usually not the case when the driver is a compression driver, as in my case.

However, at the link given here:

http://www.the12volt.com/caraudio/crosscalc3.asp#zobel

there is an online Zobel-calculator that based on the description seems to do what I search for.

1. The calculator asks for the “Nominal resistance”. In my case, is that the 16 Ohm (because it is said to be an 16 Ohm driver), or the Re = 8.9 Ohm provided by BMS, or…??

2. Is the formula in the link the way to go, or should I rather do something else - and in that case what?

I would really appreciate your help – thanks!


Regards
Peter


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