HallMarc Novice Contributor
Number of posts : 56 Age : 43 Location : West Point, Ms Registration date : 2011-05-08
| Subject: Port ? Tue May 10, 2011 11:03 pm | |
| See if you can fallow me on this one... When you put dimensions and whatnot into a port calculator, desired port size and tuning fq, it gives you a length. BUT, does it automatically take out the displacement of the port???
Say you have a port 12x4 (just for example) and a box after all displacement is exactly 3ft3... (This is using the port calc on 12volt.com...) @45hz it gives you a length of 15.574826200688225, round it down that's 15-9/16. Assuming 3/4" materials external port would be 5.5x13.5x15-9/16, port displacement would be 0.6687. That makes your total box vol 2.3313ft3... Now, a 12x4x15-9/16 port in a 2.3313ft3 box would tune to 51.06hz... Following me?
I know of a couple port calculators and all of them give about the same info as far as port length... Maybe I'm just putting too much thought into it. I could understand it if your port was external because then your not adding port displacement to your box volume. Which brings me to another question; What or is there a difference between internal or external ports? What about half internal and half external? I mean, You'd have the same amount of port area, right??? | |
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Thomas HUFFman Basic Contributor
Number of posts : 453 Age : 40 Location : West Point MS Registration date : 2011-05-07
| Subject: Re: Port ? Tue May 10, 2011 11:13 pm | |
| The half internal and half external was how the 3 Nighshade 12's were in the colorado with the bed cut, it was 14'' long and 9 inches of it was out in front of the subs. I even still got some pics of that. | |
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