Originally Posted by joxr
about 2900 cubic feet
Seating distance is about 8-9' .. listen levels around -10db
Im just wondering if you run your towers as small are the extra woofers doing anything if you are cross'd at 80
Most definitely. A small single woofer tends to distort quite fast in the 80-300 Hz range, so having 2-3 woofers covering this range makes the speaker more capable with lower distortion and better sound quality. If you never want to listen at higher than conversational levels it of course won't matter in terms of power handling, distortion, etc. Other factors come in to play for some such as aesthetics, as to whether you like how small speakers balancing on stands look compared to a normal tower speaker etc.
-10 dB requires 95 dB *peaks* at the listening position...most bookshelves will have a fair bit of distortion coming into play at that level. For example, using a small inexpensive but well designed and well regarded speaker of above average sensitive, the Ascend CBM-170 bookshelf speaker is hitting about 5% distortion from the single small woofer at 95 dB at 2m. Distortion at your listening distance at that level would be higher, since room and boundary gain is not going to increase sensitivity over the frequency range in which the woofer is distorting.
To further this, anyone who is optimizing spekaers for sound quality will be adding eq to the speaker below 300 Hz. At bare minimum, room eq will likely add 3-6 dB of eq, which doubles or quadruples the amount of power being dumped into the speaker. This will skyrocket distortion. Yep, things will sound intolerably loud from this.
A tower speaker will play quite a bit louder before this distortion sets in. Happens at lower levels than people realize.
Bookshelves are fine for some, but towers hold very clear advantages in many regards even when crossed to subs.
Here is another much more expensive, very well designed, highly regarded bookshelf speaker at 90 dB @ 2m. 10% distortion at 100 Hz
the steeply rising lower black line is distortion level)
Again, increase output to account for distance greater than 2m, eq, etc.