Jon -
Jim, one question on the songcenter - would it be better to mount it vertically? Horizontal gets the drivers closer to the screen but vertical would maintain a vertical dispersion pattern. I guess the ultimate would be an acoustically transparent screen with the center mounted vertically behind the screen. Or does it not matter that much?
Interesting question.
Obviously, the best option would be to mount the speaker vertically. If you could do that, perhaps a third SongTower behind a transparent screen would be an even better option. But let's take a look at what is going on here and see if there is much of an issue to be concerned about.
If you measure any MTM speaker (midwoofer-tweeter-midwoofer), like the SongTower, on axis at the tweeter level, you will have a reference frequency response graph. Now, if you take a series of measurements at various distances above and below the tweeter, you will see that the FR graphs are not quite the same. This is generally not a significant issue. When you walk around the room, you will not notice a change in FR since your ears will always be a constant distance above the tweeter level. So the response you hear does not change significantly until you are far off-axis. (With the SongTowers, even 60-degrees off axis the response is very good.)
If you mounted these speakers horizontally and walked around the room, to the extent that these variations in FR were audible, you would hear the changes since you would be varying your position above and below (in this case to the left and right) of the tweeter axis.
So the best option would be to mount the center channel vertically as it would eliminate these variations. But is it a problem if you mounted the center channel horizontally? Not really.
When using the speakers in a home theater application, you will normally be seated and in a constant relationship with the center channel. So you will not hear any changes in FR response from that speaker. What little variation there would be in response from the left and right mains would most likely not be noticeable either (unless you have an incredible sense of hearing).
So, in theory, vertical positioning of the center channel would be ideal. But as a practical matter in a home theater application, unless you are a purest and are obsessed with theoretical perfection, it really doesn't matter.
What is more important is that the center channel is as close to the center of the screen as your set-up permits. The dialog is almost always delivered by the center channel. And since the characters are on screen, it is important that the sound of their voices appear to eminate from there as well.
I hope that helps.
- Jim
