Krakin Posted February 11, 2014 Report Share Posted February 11, 2014 This should cover a lot of this topic. A lot of the problem with the SPL being lower with a door/window closed is due to destructive interference. To get destructive interference you require several conditions be present at the same time. The first condition is there has to be a reflective surface and/ or speaker.This reflective surface/speaker needs to reflect the wave back into another wave, known as the angle of incidence. This wave also has to be the same frequency of the other. This occurs at a distance that has to be within quarter of a wave length of the wave being affected by destructive interference. Take this as an example, inside of an enclosure you may have suitable reflective surfaces, at a suitable angle incidence, the frequency are the same, however it is missing one vital aspect to cause destructive interference. The distance between the reflective surfaces are NOT on quarter length apart. (unless your enclosure is huge) So with the windows we have a reflective surface, at an angle of incidence to another surface (the opposite window) therefore we can calculate the first destructive frequency be measuring that distance and dividing by four. The highest frequency a subwoofer should be playing is around 80 Hz, therefore the distance has to be a minimum of 3.6 feet between reflective surfaces. If we measure the distance between the windows we can confirm that the frequency at which this first null will occur. This is likely to be caused by acoustic loading. http://www.trueaudio.com/st_spcs1.htm By reducing the loading, you decrease the SPL. The steradians loading is the reason why people love listening to bass in a car. 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...
tacomaguy1 Posted February 11, 2014 Report Share Posted February 11, 2014 One window down is loudest here.....will roll with it cracked no matter how cold for that reason Team Flex Issues Link to comment Share on other sites More sharing options...
Miguels Posted February 11, 2014 Report Share Posted February 11, 2014 so that explains everything.. bass in my car i love it and the louder the better.. at home i can honestly say i hate it and it irritates me my logshttp://www.stevemead...-my-new-set-up/my blow through loghttp://www.stevemead...future-updates/ 96 ss http://www.stevemeadedesigns.com/board/topic/164094-96-impala-ss-build/ Link to comment Share on other sites More sharing options...
Dude2800 Posted February 11, 2014 Report Share Posted February 11, 2014 Mines seems to be louder too. It would be nice to have a termlab for experiments. For some of the competition guys, is it ever louder sealed? Link to comment Share on other sites More sharing options...
tacomaguy1 Posted February 11, 2014 Report Share Posted February 11, 2014 Mines seems to be louder too. It would be nice to have a termlab for experiments. For some of the competition guys, is it ever louder sealed? Not usually, but there's always exceptions Burp/spl vehicles like crx's that are built for being sealed can lose with a window down Team Flex Issues Link to comment Share on other sites More sharing options...
DireRaptor22 Posted February 11, 2014 Report Share Posted February 11, 2014 People outside the car can also hear it better when you roll the windows down. It's always more fun to cruise by a Wal Mart entrance with windows down and bass full blast. People just can't resist turning to look at what's shaking the ground “The fascination of flight can't be expressed with words. But it really lies beyond the capabilities of human endeavor. Once you've experienced it, you'll never be able to forget it.” - Friedrich Oblessor Link to comment Share on other sites More sharing options...
Katt Posted February 11, 2014 Report Share Posted February 11, 2014 People outside the car can also hear it better when you roll the windows down. It's always more fun to cruise by a Wal Mart entrance with windows down and bass full blast. People just can't resist turning to look at what's shaking the ground I work at wal-mart and you're that asshole that does that. Or pulls into the auto center full tilt. And the reason people are pissed at us bassheads. *06 330i - Sundern x12 - saz-3500* *91 Foxbody V1 S-Trim Notch* Link to comment Share on other sites More sharing options...
alaskanzx5 Posted February 11, 2014 Report Share Posted February 11, 2014 yeah sorry direraptor22 but you will get a lot of hate here with that attitude. its called be respectful to others. driving around blasting music to annoy others will just piss people off and gives us bass heads the bad name that we have. rather then making everyone else listen to what you want to hear keep it respectful rather then disturbing the peace and giving people to push for more strict laws on bassheads. t1500bdcp 2 t2d4 15" 1 t600.4 1 t400.2 1 set p1 tweets singer alt, tons of wiring, smd vm-1, 80prs, back seat delete, still in the works, aiming for a 145-147 with the ability to play 25hz up to 50hz. Link to comment Share on other sites More sharing options...
Kyblack76 Posted February 11, 2014 Report Share Posted February 11, 2014 Mines seems to be louder too. It would be nice to have a termlab for experiments. For some of the competition guys, is it ever louder sealed? Not usually, but there's always exceptions Burp/spl vehicles like crx's that are built for being sealed can lose with a window down Tim's on it. Most will gain with something open. Door, window down, all that. A big reason a lot of us, only post legal (sealed) scores. But, there are builds and enclosures that will fall straight on their ass when anything is vented/open. I meter sealed up, and demo first sealed up, then crack the window to get the "second" HUH? face... SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
Kyblack76 Posted February 11, 2014 Report Share Posted February 11, 2014 People outside the car can also hear it better when you roll the windows down. It's always more fun to cruise by a Wal Mart entrance with windows down and bass full blast. People just can't resist turning to look at what's shaking the ground and, im not gonna touch that.... SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
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