I'm getting my hands into 4th order, been playing around on the 4th order calculator on carstereo.com. It obviously doesn't take into account the acoustics of a vehicle, so I'm having trouble simply with finding the right sizes for the front and rear chambers, and the tuning. I get the S value, and the parameters for the woofer. The passband (-3db point on both ends of the spectrum) draws up different between the carstereo.com calculator and winisd. And not by a little, but by a lot.
So kind of stumped. I understand Qtc when it comes to a sealed enclosure, and I'm sure that would apply somehow considering there is a sealed porting.
The way I see it, you basically boost the Qtc (as in the frequency response) with the ported side. Now how that reacts in the vehicle, idk. I would think the cutoff frequencies would be the same whether in a vehicle or not, just certain ranges would be boosted (aka louder) than others, due to putting the enclosure in a vehicle. The ported portion would boost a certain frequency range, but how that would actually play out in a vehicle would be different than free-air.
I also understand how to use the S factor, but don't know exactly what that number means, or how it is derived.
So, that's where I stand.
