where should I aim the port/sub?

[weikertball]

I'll be using an Elemental Designs 19Ov.2 whenever it gets here for some HT useage in my basement. It's a small box subwoofer and the recommended enclosure for it for car audio is 3 cubic foot ported. Now I thought I would throw it in a large box (9+ cubic foot) tuned fairly low, below 20 hz. It will be placed in a corner so what would be a good place to aim the port and sub? I thought port aimed towards one of the walls and have the sub downfiring? I could go IB but being in a basement would make it kind of difficult. Any help would be appreciated.

[zobsky]

make sure your sub is suitable for downfiring applications. If so, then downfire it and sidefire the port, or downfire both.

[weikertball]

oh yeah, I forgot to check if it's "downfireable" If it isn't then what? Thanks for the quick reply!

[Andy Westcott]

That's an interesting point:
In the interests of furthering my education on such matters, what would make a driver unsuitable for downward firing?

[weikertball]

http://www.adireaudio.com/Files/Tech...rientation.pdf

[AndrewT]

Hi,
Adire's calculations for "sag" seem too simple.

Quoting from the pdf that Weikertball posted.

Mms =1 / [(2*Pi*Fs)^2*Cms]
sag=Cms*Mms*g = g / [2*Pi*Fs]^2

so sag depends of Fs squared, as I said it sounds too simple.

Can anyone confirm the calculation method from another source?

Going a little further,

Xmax > 4970 / Fs^2
for sag to be less than 5% of Xmax.

As Adire said "go, do the numbers for your downfiring driver".

[Ranthum]

The way I understand it, most drivers are can be downfired but some will sag too far and really cut into their output through a much shorter xmax. I prefer the driver facing outwards because I like to look at it and don't have to worry about it sagging over time. And your port shouldn't face a wall if it's too close as that might block some of the port output and alter the tuning.

[weikertball]

so, should I downfire the sub and port or just have the subwoofer downfired and have the port firing to the side towards a wall? Would it work if I made the box really tall and have the sub downfired with ports firing towards the ceiling??

[Big Kev !]

I always thought it was best to aim the port in the same direction as the driver, although I've seen many many designs that contradict this. The downfiring woofer and forward firing port seems to be a common design in many commercial woofers.

[Ranthum]

You want to make sure that the port opening inside the box isn't placed too close to the back of the sub. The sub will force more air out of the port that should be coming out and it will change the tuning and make it sound like crap. The right angle design is common in many commercial subs with a downfiring woofer and sidefiring port. It's up to you as to how you want it to look, but as long as the port isn't too close to the sub or any walls, you should be ok.