Are questions about speaker design allowed?
I have always wanted to post a question asking what the major differences were between a PA speaker, a guitar cab, mixing speakers coaxial speakers, etc.
The way you have asked this question would make it off topic, however as AJ says, there is a core question which can be on topic, which based on your Music.SE question may be appropriate here.
I completely disagree. I would say "On Topic" (though the way you phrased it was very broad I wouldn't know where to start answering.)
Last I checked, theatrical sound design was technically on topic. Loudspeaker choice and an understanding of loudspeakers has a massive impact when you are trying to reproduce sounds in a small or midsize theater. I would personally love to know more about this. Speakers come in to play when recording electric instruments too.
I think this is off topic. Not that it's not a valid question, but we can discuss anything that 'influences' the sound 'design' this way. Isn't this place about the actual creation of sound(s) and not the general amplification of them?
If you would be experimenting with shaping sounds through speakers (a technique called worldizing), like what they did with treebeard in Lord of the Rings, then it would be on topic.