BassDoctor Posted March 6, 2014 Author Report Share Posted March 6, 2014 Thanks for the replies guys, these are the replies that I was hoping to get. I'll look into everything that you both have suggested. 04 Honda Accord LX Sedan Kenwood Excelon X998 XS Power D3400 XS Power D1200 Singer 275A alternator with factory bypass 64 sqft SecondSkin Damplifier Build to be decided Link to comment Share on other sites More sharing options...
shogen Posted March 7, 2014 Report Share Posted March 7, 2014 http://bitpusher.in/?p=portarea Pioneer Premier P880PRS ll Front Stage: US Acoustics 4060 - Random speakers currently ll Sub Stage: Crescendo BC3500D - 15" Xcon sealed @ 3.28 cubes ll Electrical: - Kinetik HC1800(front) NEW***DieHard P-2(rear) beaker- I know this sounds like a lot of anime bullshit, but it is true. Link to comment Share on other sites More sharing options...
Krakin Posted March 7, 2014 Report Share Posted March 7, 2014 http://bitpusher.in/?p=portarea Chrome is telling me that link contains malware and is telling me to not enter the site :( 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...
shogen Posted March 7, 2014 Report Share Posted March 7, 2014 http://bitpusher.in/?p=portareaChrome is telling me that link contains malware and is telling me to not enter the site :( You might be right... I'll message the she author Pioneer Premier P880PRS ll Front Stage: US Acoustics 4060 - Random speakers currently ll Sub Stage: Crescendo BC3500D - 15" Xcon sealed @ 3.28 cubes ll Electrical: - Kinetik HC1800(front) NEW***DieHard P-2(rear) beaker- I know this sounds like a lot of anime bullshit, but it is true. Link to comment Share on other sites More sharing options...
BassDoctor Posted March 7, 2014 Author Report Share Posted March 7, 2014 I would like to see the formula. Is there a formula to determine the proper port area for a sub? The formulas used in the calculator I posted above. http://www.carstereo.com/help/Articles.cfm?id=21 For much more detailed formulas you can check these out. http://www.diysubwoofers.org/misc/portcal.htm It can get even more complicated, but that would probably take some schooling to figure out. Using the formula from the calculator (dV>=39.37*(47hz*0.0014904)^0.5) I've gotten that I need 85.275sqin of port at the least for two DC Lvl 3 10s (sd=0.0324m/sub xmax=0.023m) in an enclosure tuned to 47hz. Would this be the port area that I'd want to use for all enclosures with these two subwoofers, no matter the size, as long as the box is tuned to the same frequency? I apologize if these questions seem stupid. 04 Honda Accord LX Sedan Kenwood Excelon X998 XS Power D3400 XS Power D1200 Singer 275A alternator with factory bypass 64 sqft SecondSkin Damplifier Build to be decided Link to comment Share on other sites More sharing options...
Krakin Posted March 7, 2014 Report Share Posted March 7, 2014 They are not stupid at all! And yes, no matter the box volume. For those two subs at that frequency you will need that amount of area for you port. 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...
gckless Posted March 7, 2014 Report Share Posted March 7, 2014 It gets pretty complicated. For example, when you're talking lower frequencies, it doesn't matter as much. But when you're ~40Hz or more, coupling with the environment becomes important. Also, math doesn't explain what happens all the time either. Like math says a square or round port will always be better. But, if you corner-load, a slot port is almost always better performing. But I guess that wasn't really OP's question. I believe that's been answered. Circles are most efficient because of less drag. "Clipping" is the biggest forum boner now. It's like witchcraft... it automatically explains just about everything people don't understand. My build log: http://www.stevemeadedesigns.com/board/topic/200295-gckless-2011-chevrolet-impala/ High resolution photos: Gilbert Kless Photography Link to comment Share on other sites More sharing options...
Krakin Posted March 7, 2014 Report Share Posted March 7, 2014 All the variables is what keeps me entertained In the lower frequencies you get a lot less usable velocity compared to playing the upper frequencies. You can test this by playing a 20 Hz tone with your doors open and listen to the chuff chuff chuff if you don't have enough. A lot of it changes with the tuning of the port, which is why WinISD is such a great learning tool. 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...
Triticum Agricolam Posted March 7, 2014 Report Share Posted March 7, 2014 Using the formula from the calculator (dV>=39.37*(47hz*0.0014904)^0.5) I've gotten that I need 85.275sqin of port at the least for two DC Lvl 3 10s (sd=0.0324m/sub xmax=0.023m) in an enclosure tuned to 47hz. Would this be the port area that I'd want to use for all enclosures with these two subwoofers, no matter the size, as long as the box is tuned to the same frequency? I apologize if these questions seem stupid. One thing to keep in mind is that formula definitely errors on the side of caution, you can probably get by with a little less than that. Things like flaring the ends of your port will help a lot. When I build I usually use a kerf bend at the port mouth to give a nice, large flare and I round over everything. If you can do that you can reduce your port area by about 30% and still avoid chuffing. Earlier I mentioned there is a formula for calculating the effective area of a rectangular port compared to a round one, here it is: D=(1.3*(X*Y)^0.625)/((X+Y)^0.25) X and Y are the length and width of the port, doesn't matter which one is which. D is the effective diameter of the port. If you want to convert D back into area the formula is: Area=(D/2)^2*3.14159 "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
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