center rear channel 6.1 question

[cebbigh]

Have just purchased an onkyo 501 receiver and am not sure if it is worthwhile putting in another speaker. Also not sure what demands are put on that channel. Is it best just to match the front center or front left and right or is it just another surround? What is the consensus on the value added by the additional channel?

[Woochifer]

In general, the rear center speaker gives a little bit more fill in the back soundstage and helps make the encirclement effect a little more convincing. It works best with 6.1 soundtracks, and at the moment, the only discrete 6.1 soundtracks are DTS ES. Less than 100 movies are encoded in DTS ES, so check the movies you're most interested in and make your own decision if playing back a DTS ES movie in that format is something you want. Dolby Digital EX is an encoded format that has a back surround track encoded in with the surround channels. And here too, I believe there are fewer than 100 movies encoded with DD EX.

If you want to connect a rear center speaker, you need to first make sure that you have enough room behind your listening position to accommodate the speaker. If you have a sofa right up against the backwall, forget about the rear center speaker. It won't work right if you're set up that way. Just position the surround speakers a little bit behind the sofa (with the tweeters preferably about 2' above ear level) and point them directly at one another. If you got some space behind the listening position, then you should definitely consider adding the back surround speaker.

The rear center speaker should be identical to the L and R surround speakers, unless you're going with dipoles, in which case you should just go with a timbre matched direct firing speaker. The horizontal center speakers should be used only where you got a TV sitting directly where a middle speaker would ideally go (and that's pretty much how most home theaters with direct view and RPTVs are setup). With the back surrounds, you don't have that problem, so a third surround speaker would work best.