Calculating room volume?

[P-Dub]

Well, in a nicely closed off room, that's easy, LxWxH. But what about the various opennings? At what point do you say, enough is enough?

Take for example a house I'm looking at renting. The main living room is nice and large, I'd estimate a 24ft x 18ft x 8ft room. But it's not closed off. At one end it opens up to a dining area and kitchen. The openning is about 10ft wide, and the dining area goes back to about 12ft to a wall. The dining area leads to the kitchen, and that extends from the dining room wall, about 24ft. In other words think of one big room, 24ft x 30ft, with a wall that cuts inbetween the two rooms starting at the 18ft point of the 30ft wall and going 14ft.

This is where a digital camera would have been handy.

To continue, the living room also has another large entrance, it's basically a split level. So it opens up to stairs leading up to a hallway and bedrooms, and to stairs leading down to a rec room. The bottom rec room, is about a 15ft by 15ft room, and there's another hallway. The stairs leading up to the bedrooms only go about 5 steps.

So if I was to have my HT in the living room, I'm assuming I have to include all that space, plus the adjacent space in the dining area and kitchen, plus the rec room space, plus the space up the stairs to the hallways.

I'm not even going to bother adding up the hallway volume.

So taking my above rough estimates.

Living room 24x18x8 = 3,456
Dining & Kitchen 24x12x8 = 2,304
Rec room 15x15x8 = 1,800
upstairs = 8x20x8 = 1,280
Total volume = 8,840 ft^3

That's a lot of volume to fill!




Paul

There are three kinds of people in this world; those that can count, and those that can't.

[Wayne A. Pflughaupt]

Paul,

This is a tough question. If you’re asking how to determine just how much space the system “sees,” the answer is definitely... “it depends.”

My system is also in a large living room. There is no “back” of the room – it opens to the dining room and kitchen, like yours does. To the left side is the front entryway. Total volume is 6200 cubic ft. It took me a pair of DIY 12” Shivas and 650 watts to adequately fill the room with high levels of low frequency down to 25Hz.

So based on my room, I used to tell people “you have to figure in all open areas,” until I got a chance to get into some other homes.

When I visited a friend with a new system and saw where it was set up, I expected the worse. It was like yours, only in reverse: This one was upstairs in the open “play area.” It was open to the entire downstairs living areas, so I figured bass would be really lame. Well, during U-571 my seat-of-the-pants impression was that he was getting some good “woofage” down to about 30Hz or so, which really surprised me. However, the HT “room” itself was fairly small and had three good sides (walls, that is). The sub was in the corner, away from the openings, which helped.

At a recent HT meet we hooked up with a local guy who had his system set up in a room off the entryway. It was a long, narrow room perhaps 10-11ft. x 19-20ft. He was set up in the front half of the room. To the right of the seating area was the opening to the entryway that was about 6 ft. wide and fully open to the 9-ft. ceiling. The entryway led to the downstairs living room and kitchen. Of course, there was open space upstairs. Again, I was surprised at the sub’s performance. My seat-of-the pants feeling was that his sub was getting substantial energy at and perhaps below 25Hz.

So getting back to your question, Paul, based on these admitted unscientific evaluations I’d say that though even though an HT area is open to other rooms, system and bass performance depends on just “how open” it is. It appears that if the immediate area has some confinement there can still be quite a bit of boundary reinforcement and cabin gain.

Regards,
Wayne A. Pflughaupt

[P-Dub]

Wayne, thanks for the excellent reply.

Unfortuneatly we didn't get the house. It would have been pretty cool to see what 2 SVS subs could do with that much volume. But for now I'll just have to see what kind of damage I can do with just 2,600 ft^3.

It sounds like the listening position comes into effect. If I'm only say 10 - 15 ft away from my subs, I'll still get maximum impact, as opposed to being downstairs, or upstairs. The old sound level decreases by the square of the distance from source. Then add in the room gain, the corner gain, and you can still have a decent sounding HT system in an open space.




Paul

There are three kinds of people in this world; those that can count, and those that can't.