im thinking aoubt building a ported box for my 2 12w3v2's. i have never built a ported box before. is there any rules different from building a sealed box? does the shape of the box matter. and how do you make a good port?
i would try out a simple program like WinISD....i even sill use it sometimes for calculations...it can be easily found as freeware on the net
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Darky, I'm not familiar with the spec's on that speaker. You can build one based off the spec sheet or using a program like jeffchilcott recommended or like BassBox Pro. I have built boxes for about 14 years now, half of which has been professionally. If you have a spec sheet, send it to me via email if you can (fosgate3@yahoo.com or fosgate3@cma.access.com) and I will be happy to look at it for you. Contrary to popular novice belief, you can't just put a port in a box and call it "ported". Generally speaking, a ported/vented enclosure is about twice the size of a sealed enclosure. Vents/ports are different sizes and shapes and it really is based on how much space in the box that you can spare and how low you want to tune the port.
The length of the port, at a given size opening will help tune the port to a specific frequency, all to enhance that frequency. For instance, in my 1991 Ranger, I did a bed cut for one Kicker Solobaric 10L7 in a 1.7 cubic foot box with a 3x10 inch port (3 inch PVC pipe x 10inches long). This was tuned pretty low, I think to around 35Hz? (it's been some time since I first built that).
rectangle Vent or cylindrical pvc Port? That's another common question that I have asked. Personally, I like vents b/c you can really make them look good with a little time and a good router! There is a method of converting a port dimension into a vent. If you need to know, pm me and I will explain. I have heard more wind noise on ports than I have on vents--even after rounding the edges down on the port. Other than the windnoise (and it's extremely minimal as well, if you do it right) It's hard to notice any difference between a box with a port and a box with a vent. Very hard. In fact, I have never heard of anyone saying one is better than the other. That's not to say one is or isn't better than the other, only just that I've never heard about it. I have used both styles and have been extremely successful with each.
I hope this helps. Let me know if I can do anything else.
Do not forget to figure in the driver displacement as well as the ports displacement.
Thank you audiokid1. Those are both important facets to consider especially if you want the box tuned *exactly* to the desired frequency and you want a precise performance.
I will say that it has been my experience that driver displacement and port/vent displacement has not made much noticeable difference in sound performance for the one's that I have taken the time to do. In fact the difference in air space for driver displacement is so minute that usually, I don't bother to calculate it. Port/vent displacement could make a slight difference but most of us I'm afraid are too deaf to know! hehehe
I would say that unless you are going to the IASCA Finals with this system, in which case you would want the most perfected system possible, I would not lose any sleep over whether or not you considered that .01 cubic feet of driver displacement and .1 cubic feet of port displacement. Most of the spec sheets you get that show optimal performance on a woofer are computer made to begin with. Trust me, I have proven the computer wrong before. I know that I have had numerous conversations with Kicker's tech support about my old system (1 Solobaric 10L7 in a bedcut in a 1991 Ranger, ported with 3x10 and a 1.7 cubic foot box) that they said would not perform great but let me tell ya, it did! 140 on the dash which, given the location and constraint in the vehicle and the fact it is only one sub, that's not too bad!
What is even more interesting is the fact that different computer programs and calculators give different results if you can believe that. For instance: David Wood (the same who's purple MX-6 made it to the 2003 Feb issue of Car Audio and Electronics and the 2000 Feb issue of Auto Sound and Security) had a special Cascio calculator awarded to him by Orion, made specifically to calculate port size, box size, and even graph the information using the T-S parameters. He put in the data for my box and compared it to the response that BassBox Pro gave... it was different though the parameters were all the same. Then we called Kicker and that was still different. So, you can't always trust everything a computer gives you... I don't know why I put all this in here, I guess I just felt like it.... *shrug*