Jay

iTrader: (2)

I am in the process of building a sealed box for my sub, based on the supplied dimensions from the manufacturer. Plugging the numbers into WinISD it looks on the graph to be a better choice to go with a much larger ported box.

So why would the manufacturer recommend something different? With the small sealed, and ported there is a peak before dropping off, but the large ported box is pretty flat down to about 30hz with a slight peak at 26hz and then drops off with an F3 of around 22hz, but this is with a 3.231 ft^3 ported box, which will be more difficult to get in the car.

Gummie

You can almost always get a flatter response from a ported enclosure than a sealed enclosure. End of story, there’s no possible room for argument here. There are two forces at play with the manufacture’s recommended box. The first is that almost everyone and their mom wants to run a sub. It’s suddenly become the thing to do. Since the average consumer is a finicky consumer and doesn’t want to give up much trunk space, subs are designed to operate in small enclosures and manufacturers will frequently lower their spec in order to sell more subs. The average consumer won’t know the difference and won’t care if you point it out to them.

The other thing is that some woofers don’t do very well sealed. I forget exactly what Q value it centers around but you can usually tell how a speaker will do in a ported/sealed enclosure based on this spec. Maybe Jim will step in and give some more info?

Aside from these reason’s there one additional thing that winISD won’t show you and that’s cabin gain. Cabin gain acts as a boost in lower frequency sound. This means that your average sealed enclosure will play ‘about’ flat in a car and a ported enclosure designed to play flat will have a bump in output. Don’t forget that the average consumer would have no idea how to build a ported box either. It was a nightmare trying to explain a box I built for a friend to him.

Jay

iTrader: (2)

I think for now i'm going to build the box according to the dimensions supplied, especially since I had already cut the panels
It's going to be easier to get everything else installed with a small box.
3 amps, 1 processor/xover, sat tuner, power distribution with additional add-on fuse panels, passive xovers.. all start eating up real estate quickly.

Just ordered my Damplifier/Overkill/Rattle Pad this morning so hopefully this weekend I can finish the box and amp rack, and be ready to deaden everything when it comes in.

I'm going to take measurements and see about fitting in the larger ported box with everything else for a later possible project... we'll see how it goes. I think I may upgrade the front speakers before that though.

Sitting Bull

The trouble with expecting really low frequencies from your sub (40Hz and lower) is they are largely inaudible. You will feel them more than hear them. When you add in ordinary driving and road noise it is unlikely you will ever be aware of what your sub is capable of pumping out down there. So I wouldn't worry too much about having a ported enclosure. In a car it is almost entirely a waste