How does a box with 1 8" areo port work so well?

[sbg]

I am in no way a master at box design or know all to be known about how boxs work.

I have been seeing all kinds of people with boxs. That have like 4 12s in 5cuft with one 8" areo port. And they are loud and get low/move a lot of air. How is this working? Like I have been wanting to build a new box for my HHR, my box now is just over 8 cuft net. With 4 -6" round ports. 113" port area and 12.62 port per. Tuned to 37Hz. It does well gets kinda loud don't play lows all that good. So how is it I see a other guy with with the 4 12s in a box with 1 8" port. With 50" port area and 8" port per play lows better then I can and be louder...

[sbg]

I ask because I would like to build a much small box then I have now and use one areo port, But when I try to design something like that it don't seem to work out

[Triticum Agricolam]

Well here are a couple things to think about.

Its tough to compare different setups in different vehicles, there is probably a lot more that is different than just the size and type of ports being used, so I wouldn't draw too many conclusions just from that.

Round/aero ports are very space efficient if you can use one large one. Once you start using multiples the advantage diminishes. If you are using three or more round/aero ports you would probably be better off with a slot port at that point.

Just because someone is getting loud with their current setup doesn't mean they couldn't get louder with some changes. A single 8" port for four 12"s in a 5 cubic foot box is a pretty low port area combination. Its going to depend on how much power the person is running, but I bet they would benefit from more port area. Once port velocity gets too high the port will compress, which eats the output for lunch.

Port area shouldn't effect frequency response/bandwidth. If it is its because the port is undersized and is compressing, which will reduce the peaky nature of a box at max volume, but it comes at a terrible cost of decreased output.

[sbg]

Well here are a couple things to think about.

Its tough to compare different setups in different vehicles, there is probably a lot more that is different than just the size and type of ports being used, so I wouldn't draw too many conclusions just from that.

Round/aero ports are very space efficient if you can use one large one. Once you start using multiples the advantage diminishes. If you are using three or more round/aero ports you would probably be better off with a slot port at that point.

Just because someone is getting loud with their current setup doesn't mean they couldn't get louder with some changes. A single 8" port for four 12"s in a 5 cubic foot box is a pretty low port area combination. Its going to depend on how much power the person is running, but I bet they would benefit from more port area. Once port velocity gets too high the port will compress, which eats the output for lunch.

Port area shouldn't effect frequency response/bandwidth. If it is its because the port is undersized and is compressing, which will reduce the peaky nature of a box at max volume, but it comes at a terrible cost of decreased output.

Lot to think of.i want to make a box like that work. So port per foot is more important then port area?

[Triticum Agricolam]

Lot to think of.i want to make a box like that work. So port per foot is more important then port area?

I would say no, port area per foot is not more important than port area. Neither is really a good way to determine what the right amount port area you need is. There are just too many variables. The problem with "port area per foot" is it doesn't account for how much power is going to be used, or tuning frequency. Obviously a 3,000 watt system needs more port area than a 300 watt would, even if they were in the same size box. The problem with fixed port area recommendations is they don't account for box size or tuning frequency either. For example, Sundown recommends 40 sq in of port area for the Z.v4-12 and that's a good amount in their recommended 2.5 cu ft box tuned to 32 hz on RMS power. But if you put the same sub in a 1.5 cube box tuned to 26 hz, now you don't need as much port area.

Like most things, port area can be a complicated problem if you want to get as close to 100% performance as possible. Seems to me like the car audio community sometimes tries to over simplify things. Port area per cube rules are a good example of that. They will usually get you at least 90%, but if you want that extra 10% you are going to need to use more sophisticated methods.

ETA: If you ever aren't sure, erroring on the high side when it comes to port area is almost never a bad thing. It just takes up more space.