Alesis M1Active Série Manuel D'utilisation Du Propriétaire page 14

Speaker Orientation:
The M1Active 520/620 has been designed for maximum flexibility when it comes
to speaker orientation (i.e., whether the speaker is upright or laying down on its
side). For best performance, place the speakers vertically with the tweeter on top.
If this is not practical in your control room, go ahead and lay each speaker on its
side, but make sure the tweeters are on the "inside" and are closer to the engineer.
This will give you the best possible soundstaging for this orientation. Avoid
having the tweeter on the "outside" since the added distance between the tweeters
may result in a "gap" in the middle of your soundstage.
12
Ideal Orientation
Acceptable Orientation
(tweeters on the inside)
Poor Orientation
(tweeters on the outside)