A center channel speaker is the most important speaker in your sound system. And because of this, it is advised that you use a speaker aimed to provide a great center channel listening experience - focusing on bass, vocals and tuned to accurate dialogue reproduction. Clear vocals are crucial. A good center speaker should have a "three-way design" with a vertically-aligned tweeter and midrange. So if your chosen speaker has these main qualities, you can try using it as a center speaker but always opt to purchase a speaker designed for these purposes.