external ports

[dudeogo]

are external ports calculated the same way as internal? and also, it is totally safe to reverse polarity on subs for invert mount? (Not asking if it required, just if it is totally safe)

[Joe X]

External ports have no box displacement, yes it's safe to reverse polarity, subs reverse mounted have a small negative driver displacement.

[dudeogo]

External ports have no box displacement, yes it's safe to reverse polarity, subs reverse mounted have a small negative driver displacement.

Okay, the no displacement is why I had picked it in the first place, because I am squeezing 2 SA-15s in the trunk of my bonneville. Thanks for reassuring me on inverting I was pretty sold on it but had heard some people say you had to reverse polarity and some say you didn't, I just wanted to make sure I was being safe on my subs either way.

[dudeogo]

PS totally sorry in advance for the noob questions. I am only 16, and am moving from one rockford p3 12, in a box I just found on craigslist, to a real system, being a 2400 watt cea 06 certified amp and 2 sa 15s in a ported box I'll build myself. Still learning and trying to get better!

[Joe X]

You're gonna love this forum then, keep asking anything you need.

[ckeeler11]

its great to see youngster get involved. post p pictures when you get to building.

Asking questions is how you gain knowledge.

[reedal]

The only time reversing polarity for subwoofers is required is if you have one sub inverted while the other is not, while using the same airspace/enclosure. I know it's not what you asked, but you should know, because it's good info to know. If both/all subs are mounted the same way, then there's no point in reversing the polarity, as it won't change anything. If you have one sub inverted while the other is not, and you do not reverse the polarity on one, the subs will be out of phase, which will reduce output immensely, and could damage one or both potentially.

Keep learning a good understanding of basic electronics can go a long way in the car audio world. bcae1.com is a great source for beginners if you haven't already checked it out.

[MrSkippyJ]

Well you don't want your subs out of phase with the rest of your system either.

[dudeogo]

The only time reversing polarity for subwoofers is required is if you have one sub inverted while the other is not, while using the same airspace/enclosure. I know it's not what you asked, but you should know, because it's good info to know. If both/all subs are mounted the same way, then there's no point in reversing the polarity, as it won't change anything. If you have one sub inverted while the other is not, and you do not reverse the polarity on one, the subs will be out of phase, which will reduce output immensely, and could damage one or both potentially.

Keep learning a good understanding of basic electronics can go a long way in the car audio world. bcae1.com is a great source for beginners if you haven't already checked it out.

Yeah I knew about the isobaric thing thanks though I'll try reversed and normal and see what sounds better!

[dudeogo]

Also! Since I am doing an external port, would inverted subs back, ext port front work? if so I can port through the ski pass of my car. I could probably swing subs inverted back and port external back though. I have a massive trunk.