Alan,
With regards to your car stereo analogy, what you typed seems most logical, but hasn't always seemed to be the case with what I've noticed in practice. I've never really thought about why it happens, but I distincly remember cracking the front windows just a few inches and listening to the bass become much more full and natural sounding. It would appear to go deeper and with less effort. I've noticed this in different cars with different systems.
Is it because there is too much pressure in front of the woofer cones? Is it because the waves can escape before there are too many wave reflections that could cause cancellation (this is blatant speculation on my behalf and very well may make no sense whatsoever)?
I have a 1999 Dodge Intrepid right now that I replaced the stock speakers with Polk Momo coaxials, and I replaced the factory deck with a Pioneer model (that I love). I put in a significant boost at 40 Hz and can notice what I'm talking about even without a subwoofer.
Any ideas anyone?
