Originally Posted by dhodgson7
just about to purchase a set of book shelf speakers for the living room (not Home Theatre), they'll be used for watching movies and listening to music.
The speakers will have a space behind them about 10 - 15cm due to a wall and will be mounted on speaker stands. I'll be using a denon 2312 to drive them.
I was thinking of B&W CM1's but since they are rear ported would the sound quality be massivly impacted by the limited space? If so I was then looking at B&W 685's since they are front ported.
Once you have that much space (a port diameter like Bill points out) so you're not effectively lengthening the port and changing its resonance it doesn't matter what side the ports are on (even at 100Hz sound waves are 3.4 meters long and wrap around anything you can fit in your living room like it wasn't there so what you hear doesn't depend on what direction the source is facing).
The big issue is that you need speakers voiced specifically for near-wall use. I'd buy in-wall speakers (with MDF enclosures) if I owned the place and on-wall speakers if I didn't instead of trying to make stand mounted speakers work in the location.
Both designs won't have the baffle step compensation needed for free standing use that yields too much bass near a room boundary and singers that sound like they have chest colds. This also allows them to be 3-6dB more sensitive for more headroom than the same drivers in a speaker built for free standing use. The in-wall designs also won't have an SBIR null from the front wall proximity (where the path length of the reflection is enough for the sound to make a 180 degree phase shift and cancel. Sound travels about 340 meters/second; so a speaker 20cm deep 10cm from the wall which puts the mid-bass .3 meters off the wall would have a notch at 340 / 4 / .3 = about 280Hz) or enclosure diffraction.
Sound stage depth will be less than you get with properly placed free-standing speakers but you're already giving that up by not keeping your speakers a healthy distance off the front wall (100 - 150cm is a nice number).