Sorry I stole this from another site. But, would this not be true and accurate.
I think that's called Bass Management. And Bass Mangement is the key to this discussion.
If you have a receiver/pre/pro with a modern Bass Mangement scheme, and you have satellite speakers with sufficient mid-bass capability, (i.e., 60 Hz or so), then a system comprised of satellites and subwoofer(s) can sound at least as good, and often, better than a system comprised of "full-range" mains. Why is this??? Several reasons:
1. Most "full-range" mains are not really full-range. In order to be full range for HT purposes, the mains need to have sufficient output at 20 Hz. Very few large, floorstanding speakrs have any output at 20 Hz. Most are limited to the low 30's or high 20's, at best. So, what happens when you send them a "full-range" signal? The deepest notes are.......
LOST!
Let me re-iterate... they are not reproduced.
However, if you use Bass Mangement to "filter the low frequencies from the main channels and send them to the subwoofer", (and presumably the subwoofer has deeper extension than the mains), they
WILL be reproduced...
by the subwoofer.
2. (Sanjay's point") The best location for bass reproduction in any room is rarely the best location for the main speaker for the purposes of imaging and soundstage. For the main speakers to do their best at presenting the audio image locked up with the video image, the mains should usually be well away from boundary walls. However, bass is reinforced by boundary walls, and often the best location for bass reproduction takes the main speakers out of their best location for imaging and soundstage.
Siphon the bass off to the subwoofer and you free up the mains to be placed where they provide the best audio/visual "image". You can then place the subwoofer(s) where they interact best with the room and the listening position to provide flat, deep, clean bass.
3. Amplifier efficiency. When you use BM to re-direct the bass frequencies to the subwofer(s), you filter it out before the amplifiers. Since bass frequencies are the most power hungry part of the audio spectrum, removing them from the main channels and re-directing them to the sub(s), frees up the main amps to do a better job of powering the frequencies they are asked to reproduce. This allows the entire system, (speakers, amps and subwoofer(s)) to play louder and with less distortion.
Bottom line, if you have a system that consists of:
...true, full-range, 20 Hz to 20 kHz speakers...
...AND those speakers can be placed where they provide a perfect soundstage AND excellent bass reproduction,
...AND you have HUGE amplifier capabilty that can power those full-range speakers to limitless SPL's without clipping,
...then you don't need Bass Managment.
OTOH, if you're like the rest of us, Bass Management will be the best thing since sliced bead.
