Krakin Posted November 18, 2014 Report Share Posted November 18, 2014 Always build your port area with you xmax parameter. Power only matters if you are very well experienced and don't want to ever upgrade an amp, ever. 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 November 18, 2014 Report Share Posted November 18, 2014 Good point above. Regardless of power, Xmax is Xmax. The sub WILL NOT reliably move more than that, just less if feeding less power/not near tuning frequency. I have to ask, if you're listening to country, why not stick with a sealed enclosure? It's a personal preference, but for accoustic bass (rock, country, alternative, ect.) I tend to like the sound of a sealed enclosure better than ported. I always go ported for rap/hip hop/electronic music. 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...
mylesshivers Posted November 18, 2014 Author Report Share Posted November 18, 2014 Good point above. Regardless of power, Xmax is Xmax. The sub WILL NOT reliably move more than that, just less if feeding less power/not near tuning frequency. I have to ask, if you're listening to country, why not stick with a sealed enclosure? It's a personal preference, but for accoustic bass (rock, country, alternative, ect.) I tend to like the sound of a sealed enclosure better than ported. I always go ported for rap/hip hop/electronic music. Okay, I have thought about sealed, but I have fallen into the trap that ported is louder and "shakes" more. Link to comment Share on other sites More sharing options...
Krakin Posted November 18, 2014 Report Share Posted November 18, 2014 Only around tuning. But a low tuned enclosure will have a very fast group delay close to a sealed enclosure and the extended bass shelf of the wave manipulation of ported enclosures. 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...
mylesshivers Posted November 18, 2014 Author Report Share Posted November 18, 2014 Only around tuning. But a low tuned enclosure will have a very fast group delay close to a sealed enclosure and the extended bass shelf of the wave manipulation of ported enclosures. What do you mean only around tuning? So is this what you are say..... if I tune a ported(slot or aero) box lower to something along the lines of 25 hz. It will have faster response and more back pressure, but also move air and be louder than a sealed enclosure? Link to comment Share on other sites More sharing options...
Krakin Posted November 18, 2014 Report Share Posted November 18, 2014 Get a modeling software like WinISD and just make a few scenarios and see what happens. 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...
Joe X Posted November 18, 2014 Report Share Posted November 18, 2014 OK, y'all are very, very informative, I am actually starting to get overwhelmed. Let me know if this is correct, Since I am overpowering the subwoofer there needs to be more port area because of more airspeed. Slot ports require larger box's. My set max dimensions are L = 30" H = 14". The width is flexible up to 13" My "application" and goals is for a daily driver, I listen to country all the time, but love the bass. I would like the box to be thin enough to be able to put golf clubs on my trunk without having to worry. I also have a question, do I need to power it at 600 rms to be able to correctly and effectively determine to port area? If you are overpowering the sub you will most likely benefit from ported to evacuate heat if you are not reverse mounting the sub, to improve transient response limit net volume, probably 1.75 net and tune low like say 30-32 Hz, give ample port area as possible, pretty sure some 32 square inches of slot port area will be more than enough at that tuning range, if you want a displacement/tuning based way to calculate port area look into Richard H. Small's estimate, you need to feed real data to it for it to work well. Link to comment Share on other sites More sharing options...
mylesshivers Posted November 18, 2014 Author Report Share Posted November 18, 2014 Richard H. Small's estimate, Where can this be located? Link to comment Share on other sites More sharing options...
Krakin Posted November 18, 2014 Report Share Posted November 18, 2014 The first response. All it is, is converted the metric units and simplified the expression for most people to use. Another estimate he used was having the velocity of the air of the port have at most a speed of 15 m/s. 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...
Joe X Posted November 18, 2014 Report Share Posted November 18, 2014 The first response. All it is, is converted the metric units and simplified the expression for most people to use. Another estimate he used was having the velocity of the air of the port have at most a speed of 15 m/s. Right is just that the calculator leads to inaccurate results as it uses a table for cone surface area that can be off significantly sometimes, higher displacement subs surround can lead to lesser cone surface area than a low displacement ones for example and Xmax of that sub is specified to 70% BL = 19mm, that may not very linear for some applications, you may also go over that in other applications. And yes the formula tries to set your max airspeed to about 4.5 % of mach but again accurate data should be used. Link to comment Share on other sites More sharing options...
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