A component speaker has separate drivers and an external crossover to designate which driver plays what frequency. The most common example of such is a standard bookshelf speaker that uses a two way design, which will look something like this:
A coaxial speaker, on the other hand, has multiple drivers that fit into the same cabinet cavity and radiate from a shared center – co-axis, hence. It looks something like this:
The main advantage of coaxial speakers is that you can get a full range woofer that only takes the space of a single cone. This works well where there are space limitations, such as in a car, the hull of a boat, or any other such location. The design is trickier though, and generally accepted to have unavoidably inferior performance, mainly because the stacked drivers will interfere with one another.
In a home theater setting, however, there’s just no real reason to use a coaxial speaker unless there’s an unusually restrictive space requirement for whatever reason. Why not just have speakers that are bigger as long as they can fit just as easily. Most home theater speakers are component anyhow, so with better selection will come better potential value.
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