Like Sean has explained, your room makes a HUGE difference in the low end of the spectrum.
I like the concept of REW but I have never gotten around to getting the rest of the equipment that is needed. I know an external sound card and a calibrated mic will be handy in by my home and cars but I'll stick with my trusty Rat Shack SPL meter for a little longer.
OK robert. You've helped me in the past, not sure if you can remember.
Is a 'home theater' sub necessary or will a car audio 18" do ? Is 4 ohm the standard for both types?
There is no such thing as a "home theater" sub or a "car" sub. Those are just marketing terms. Subs are subs and there are a few that will have the appropriate Theile/Small parameters to meet your design goals. 4 ohm isn't standard in the car audio world and hasn't been for about 10 years. My car sub is wired for 1 ohm right now. There are some high end car amps that will handle a 1/2 or even a 1/4 ohm load. My home audio subs are both wired for 2 ohms because that's the load my amp puts out the most power into while in stereo mode.
Stereo Integrity (Known as SI for years in the car audio world) has some new 15" and 18" models that are getting rave reviews from the home theater guys.http://www.stereointegrity.com/ TC Sounds is still a major player in both the car and home theater market. They are available from Parts Express and a few Ebay sellers. Speaking of PE, their Dayton line of subs is always a good choice. Sundown Audio has a new line of subs with the first pictures posted yesterday. These things are capable of huge amounts of excursion. http://www.caraudioc...ion-photos.html Finally, Pink Star Industries (PSI) Car Audio will custom build you a driver to fit your exact needs. I run one of his one-off custom models in my wife's car and have some others sitting around the house. When I say one-off, I mean it. There are no others like it. They were my design with a little help from David (the owner). http://psicaraudio.com/