Deeznutz Posted August 30, 2014 Report Share Posted August 30, 2014 Hello, I just received my 4th Coustic subwoofer today. Now time to make yet another box! I have a question about the carstereo.com free calculator. I want to build another box with a square port and this is the info I'm getting. http://www.carstereo.com/help/Articles.cfm?id=31 PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES Vent Dimensions Calculator Formulas Minimum Usable Vent Diameter The first thing you should do when calculating a vent is to determine how big it has to be. "Port noise" can ruin the sound of an otherwise good enclosure design. If you do not have the Xmax figure for your driver(s), leave the default value (it is an average value suitable for most subwoofers). If you want to use this calculator, first choose what size driver(s) you are using, then enter how many are in your enclosure. Now, enter your Xmax figure (in millimeters), and the frequency that you need to tune your vent to. And, finally click the "Calculate Minimum" button to get your results. The "Minimum Diameter" box is for round ports, and the "Minimum Area" box is the minimum area required for a square vent. If you need to convert a measurement to/from English/Metric click here, then come back. Driver Size (Inches) 12Enter Quantity of Drivers 4Enter Xmax 11.4 mmEnter Tuning Frequency 32Hertz Minimum Diameter = 10.09inches Minimum Area = 79.94 inchesLength of a sidefor a square vent = inches Calculate Your Vent Length To use this calculator, first you will need to choose whether you want a round or a square port. Then, enter your internal box volume (in cubic feet). Next, you enter either an inside diameter for the tube you are using if you want a circular port, or the inside dimensions of the square port you are going to build into your box (make sure you click the "Slot Port" button if you are designing a slot port - if you don't understand the difference between a square vent and a slot vent, clickhere). And finally, press the "Calculate Length" button at the bottom, and your answer will appear in the "Vent Length" box. Select Your Port TypeSquare Quantity of ports 1Enter Enclosure Volume 7 (ft3 )Enter Desired Tuning Frequency 32 HertzEnter Desired Square Vent Enter Height Inches 8.94 inchesEnter Width Inches 8.94 inches Vent Length Inches 23.04 inches A 9" square port x 23" long? for 4 12's? Does it sound right? I already made a 7.75" port x 23.75" long port for a 5.25cf box last week. The box sounds great, no port noise what so ever, just not knowing if I am doing this right or not to begin with!? I have read alot about port areas being 300 square inches or something so the velocity is 30m per second, etc. Just need info if I am doing this right?? Thanks in advance. -Frank Link to comment Share on other sites More sharing options...
CleanSierra Posted August 30, 2014 Report Share Posted August 30, 2014 Any links to the subs themselves? I'm not really interested in gathering that info for myself. Im not the one you want to try to troll. Just a fyi for you. Link to comment Share on other sites More sharing options...
Deeznutz Posted August 31, 2014 Author Report Share Posted August 31, 2014 http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000021249.pdf Hey CS! Here you go! -Frank Link to comment Share on other sites More sharing options...
Deeznutz Posted September 2, 2014 Author Report Share Posted September 2, 2014 Anyone? Link to comment Share on other sites More sharing options...
philrab Posted September 2, 2014 Report Share Posted September 2, 2014 No experience with them, but their spec sheet is calling for a whole LOT of port area per sub/per cubic foot. 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
Krakin Posted September 2, 2014 Report Share Posted September 2, 2014 Per cubic foot is not a way to figure how much port area you need. The calculator at the top of the first post is a fairly accurate way to find out how much is needed. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
philrab Posted September 2, 2014 Report Share Posted September 2, 2014 Per cubic foot is not a way to figure how much port area you need. The calculator at the top of the first post is a fairly accurate way to find out how much is needed. I know it's just a rule of thumb, but going off the manufacturer's recomendation they're calling for a fairly large port for a single sub in 1.25-2.0 cu ft boxes. Just saying off hand that looks like a lot more port area than what the OP is running, but if he hasn't had issues with port noise.... 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
CleanSierra Posted September 2, 2014 Report Share Posted September 2, 2014 I just ran your numbers through an online calculator and since they are low Xmax subs, 81" is enough to avoid port noise and compression. That would explain why you haven't heard any port noise Im not the one you want to try to troll. Just a fyi for you. Link to comment Share on other sites More sharing options...
Deeznutz Posted September 2, 2014 Author Report Share Posted September 2, 2014 CS, So the software I am using is fairly accurate than? Cool! Now I can run to home depot and make the box! She gets her license friday. I would like to have the system ready by than. -Frank Link to comment Share on other sites More sharing options...
CleanSierra Posted September 2, 2014 Report Share Posted September 2, 2014 You can get away with significantly less port in a vehicle than you can in a big room. The room for the wave to develop is far less and noise will be harder to distinguish in most cases. Im not the one you want to try to troll. Just a fyi for you. Link to comment Share on other sites More sharing options...
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