Crossover Capacitor In Parallel with Woofer
Sometimes what works is a second-order lowpass filter with a lower-than-normal L/C ratio and a resistor in series with the capacitor on the shunt leg. This is a damping resistor which prevents response peaking and its accompanying impedance dip. This would be called a "damped second order lowpass filter", and it can look a lot like a first order + Zobel. Duke |
It is certainly doing impedance correction, but 6 mfd sounds very low. Years ago, I rebuilt a pair of these and ran actual curves... I'm sorry, I just don't remember, but It seems to me that it was more like 20 to 40 mfd to correct the impedance bump in these. 5 ohm does sound right on the resister. |
I use ngspcie-30, downlaoded from SourceForge - a free program. https://sourceforge.net/projects/ngspice/files/ng-spice-rework/30/ Lots of info on passive and active circuits. I also use a free graphics interface called kjwaves_1.1.3 http://ngspice.sourceforge.net/kjwaves.html |
Oh, so the key difference when looking at a crossover between a 2nd order and Zobel tends to be the size of the resistor, and cap. The resistors in a Zobel are in the 4-8 Ohm range. The resistors in even numbered poles is tiny, anywhere from 0.2 to 1 Ohm. Also, the cap is smaller, since it's working up higher in frequency. I strongly recommend you try finding XSim and downloading it. It's free, and will help you simulate and see how different crossovers work. |
Sounds like a Zobel: https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-zobel_8.html The quick answer is it helps the woofer impedance stay flat so the low pass filter works more consistently. |
