Elite 12D Port Question

[Kirghiz]

If one were going to run a pair of Elites off an Elite.1 in roughly 4.5 cubic feet, would one 6" flared aero port be enough, or should one look at running a pair 6" aeros? Saw a video where a guy had 4 Elite 12's using four 4" aero ports, and was curious.

[Drock]

I would think you'd need a pair of 6". High excursion moves lots of air. I know it's not the same but my dd's made lots of port noise when I got them. They were in a spec'ed box but for some reason the port was calculated for one driver. It sounded like crap. I doubled the port size and now it sound fantastic. No idea what it's tuned to or anything. That is over my head. I just know that my 12" move a lot of air. So I think in this case bigger is better. I was running the elite.1 at 1 ohm with 2 dd3512d4's. the neighbor wasn't to happy with me.

[Mr. Wild]

One 6" aeroport is good up to about 2kW. If you plan on using all that Elite.1 power then use a pair of 6" or one 8" port.

[Kirghiz]

Yeah, that's kinda what I was thinking, but I thought I'd ask. Thanks

[audiophyle_247]

You cant judge port size by power levels, that is just absurd.

There are a LOT of factors that determine how big/small the port area needs to be.
This is a pretty handy calculator to give you a MINIMUM port area for a setup. Punch in the specs of your sub(s) and it will tell you how mush port surface area you should have based on the woofer(s) size, stroke, and enclosure's target freq.
http://www.carstereo.com/help/Articles.cfm?id=31

PG recommends a 2.5x12 port (30 sqin) PER 12" driver. A 6" aero port is almost 29sqin, so a little on the small side to begin with.
According to the calculator, 2 12" subs with an enclosure tuned to 30hz requires a MINIMUM of almost 99sqin.
That is more than 3 6" aero ports, and Ive used this calculator for years as a quick reference tool and it has been very spot on.

Keep in mind that port surface area also increases the chances of port noise, & 3 aero ports will have more port surface area than an equivalent area single port (10"x10" or an 11.2" round port).

I would just build a large single slot vent & call it a day. Aero's are over rated and way over priced.

[Mr. Wild]

I think it is pretty straightforward that required port area is determined by power level. The figures I quoted are just a rough guideline some SPL guys have figured out in practise.

If you build a box for two 10" or 12" or 15" or whatever size drivers which can only handle say 500W rms then a 100 sq inch port is just a waste of space. If the drivers can handle 10kW a 100 sq inch port won't be enough at all. So power level has everything to do with port size.

[Kirghiz]

Before and after posting this thread I was playing with vent configurations in winisd with the power I'm going to be running, and keeping the vent as short as possible, because that is the issue I'm having in the enclosure I'm working on. I was trying bigger and smaller enclosures trying to find a sweet spot. In a 4.5 Cubic enclosure I came up with a 6" x 10" slot port that is 26.5" long will be tuned at 33hz and have a vent speed of 75 mph. They say that keeping the vent speed below 10% of the speed of sound is the goal for reducing port noise, and that vent configuration seems to do that, and seemed like the best option for me in terms of keeping the vent size in line with my needs in the install, while doing it's job adequately.

But yes, more power means more air movement, which increases the vent speed, and you need a bigger port area to keep the port noise down. Too small of a port and the air is forced through too small of an opening, increasing vent speed, and causes whistling/chuffing. Considering that in my install I would practically be sitting on the enclosure, and there is no trunk to hide port noise, keeping the port quiet is real important.