2 different pairs of front left/right speakers

Do you mean two front speakers at the same time?  And two center channels at the same time?  There are few worse things I can think of that one can do to create bad sound.  Playing the same content from more than one speakers causes what is called comb filtering.  That can't be fixed, not even with Audyssey...

Yes - I have a home theater and I want to add more speakers, especially another center channel above the screen (one on top and one below).

Are subwoofers not affected by comb filtering?  I have 2 now and thinking of adding 2 more.

Hi Will,

Subwoofers are not affected because the wavelengths are so long.  But, it's a really bad idea for speakers.  You will end up with voices sounding like they are in a bathroom...that's what comb filtering sounds like.

Hmmmm............OK so I guess my logic was flawed.  I was thinking that to get the center channel some help and create a wider front (left/right) soundstage, I could just add more speakers.  

So the solution would be to add bigger speakers (for my home theater) just keeping it with the 1 center, 1 pair front L/R, 1 pair surround, and 1 pair back?

The professional movie theaters and sound rooms must have custom engineering speaker drivers with custom crossovers to eliminate this problem?

Thinking through this a little more, I think I am better off just adding another pair of front L/R speakers as DSX WIDES to get that wider soundstage I am after.  An upgrade to my pre/pro for DSX is available.

I would like to somehow give the center channel a bit more ooompfff so if you can suggest something, I am all ears.  Primarily looking for more low end.  At what frequency is the comb filter a problem?  Could I perhaps disconnect the tweeter in one of the centers?  Disconnect the tweeter and the midrange?  I'd have to see what the crossover points are before doing this.  I can easily disconnect each driver in the speaker cabinet.

Hi Will,

The notion of stereo doesn't apply to vertically spaced speakers.  It's not possible to create a solid phantom image as it is with horizontally spaced speakers.  This is because of the mechanisms we rely upon for hearing that are different in the vertical direction.  

It is possible to get a wider stage with additional wide speakers, but the content sent to these speakers has to be different than what goes to the front L and R speakers.  As you note in the followup note DSX was designed precisely for this application:

http://www.audyssey.com/audio-technology/audyssey-dsx

It sounds like you are trying to tailor the center channel response away from flat reference to something with more bass.  I would opt for an external graphic or parametric equalizer and a separate amp if that's what you are trying to achieve.  Adding more drivers is not really the way to go...  Or perhaps a center speaker with larger woofers?

My center channel speaker is much smaller than the front L/R speakers so when watching movies where most of the sound comes from that speaker it seems to be the weak link.  My thinking was to boost this by adding another center channel with each center driven by a separate amp via daisy chain from pre-outs.  

I can't buy a bigger center that is voice matched to my L/R - I'd have to replace all speakers.

 I have a choice of putting one center on top and one underneath or both side by side (underneath the screen).  Based on what you noted, I would have the comb filter issue with either scenarios even with both speakers driven by separate amps?

THANKS!

1. Try moving the xover point of the center speaker higher so that the sub takes over more of the bass duties.  

2. Get a bigger center speaker. The concern about mismatch is valid, but it will be greatly improved after running MultEQ so I wouldn't worry too much about it.

3. Separate amps will not help with comb filtering.  I strongly advise against splitting the center channel into two speakers.  You will end up with worse worse than what you have now.

OK - I think I've got it now.

Moving to the heights and wides, can these be small satellite speakers?  I'm not sure I have room for my current floorstanders to fit into that 60 degree placement.  My room is only 12 feet wide and the screen occupies almost half of that.  I was thinking I could get some small satellites and bracket mount them to the side walls so I can angle them properly.

Yes, absolutely.  Bass management will take care of redirecting the bass from these speakers to the sub.

One last question and I'll leave you alone on this:  My rear surround speakers are those angled dipole/bipole types with identical drivers on each side.  They are switch selectable monopole, dipole or bipole.

How do I set them so I do not have the comb filter issue with them?  They essentially are 2 speakers in one with the same signal coming from each side.

I have them set on bipole now. I use them for home theater and mulitichannel music.

It's best to set all surround speakers to dipole mode so they are diffuse and not localizable.

Thanks!