In reply to:
Thanks for your comment, semi_on, but a down-firing sub doesn't "amplify" the sound by bouncing it off the floor. All subwoofers couple to the floor on which they sit (it's the nearest surface) whether or not the energy emerges from a front-firing driver, a down-firing driver plus a port, a side-firing driver, or a port alone (a bandpass design where the driver is inside the enclosure, venting its energy to the room through only a port).
Thanks for the correction. What then is the functional difference between the sound that comes from a direct firing sub and a down firing sub?
They've always seemed a bit boomier to me.
