Can you help me understand why it's of the "extreme" category? It seems to me it will be a fairly typical open basement room design with a nice TV viewing area. Granted it's not a full on dedicated theater, but that's not what I intended. do I want the best I can get out of it... well yes. Over all a descent set of towers or bookshelf speakers, that I can adjust for optimal view/listening, should be able to get some pretty stellar sound??? right?
For mains, center, and surrounds, a speaker's output capability is more affected by the distance between speaker and seat. If you sit far away from your speakers and want reference-level output, your speakers better have either high sensitivity or good power handling with high wattage amplification. But if you're only a few feet from your speakers, even if you're in a huge room you can get excellent sound with low sensitivity speakers at low wattage. Most listening at normal conversational volume happens with less than a watt of power, in fact.
But for subs on the other hand, linear distance is less of a consideration than the volume of contiguous space in which the sub lives. Your theater's being open to the rest of the floor means the rest of the floor must be considered when determining what sort of output you need from your sub. Your theater space is about 2,000 cubic feet. Just eyeballing your floor plan, it appears that the total combined space exceeds 6,000 cubic feet. Rooms 5,000 feet or more fall in the Extreme category
according to AH's bassaholic scale.
See, have you ever noticed that bass is typically stronger in pickup trucks than in cars? And compact cars typically do more with a smaller subwoofer than SUVs? That effect is cabin gain. The smaller the area to be pressurized, the more profound the gain.
Extend that idea into a room in your home. Even the smallest bedroom in your house is several orders larger than the space inside a vehicle. As an aside, that's a big reason why great subwoofers for a car are often horribly suited for use in a home system. In any case, it takes a lot of effort for a speaker to produce sub bass. Within a smaller room you can often get satisfactory output from a weaker subwoofer (within reason) because room gain will provide a boost to the lowest frequencies. For a cavernous room such as your basement, you don't get the benefit of room gain. Therefore, your sub(s) need greater native output.
I feel like I'm not be explaining this very well, and I apologize. I hope someone a bit more articulate might jump in and explain it better.
