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Old 09-17-2004, 10:55 AM   #1
ike 557

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Fact or Fiction: For spl tune 10 hz below resonant frequancy

Hi

Can anyone tell me if this is true or not. I've heard of people gaining db's by tuning their boxes around 10 hz lower than the cars resonant frequency.

If this is true, can someone give a brief explanation of how or why? Also if it's true, do you burp at the box tuning or the cars resonance.

Any replies will be greatly appreciated

Thanks

Mat
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Old 09-17-2004, 11:56 AM   #2
jujumantb

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Well if you do some playing around in WinISD, you will see that a box tuned to, say, 32hz, will actually have its peak around 37-40hz. A ported box's peak is never right at the tuning frequency. So I dont think 10hz up is the magic #, it depends on the size and tune of the box.
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Old 09-17-2004, 12:25 PM   #3
free4all

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how exactly would you find your cars resonant frequency?
and if im not mistaken, theoretically if you found the cars resonant frequency, the car should rattle itself to pieces the same way that the tacoma bridge collapsed
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Old 09-17-2004, 12:51 PM   #4
Drkodin

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Quote:
Originally Posted by free4all
how exactly would you find your cars resonant frequency?
and if im not mistaken, theoretically if you found the cars resonant frequency, the car should rattle itself to pieces the same way that the tacoma bridge collapsed
totally different things. A at a res. freq. the car actually vibrates the least but there aren't any suspension parts on the chassis of the car. NOw if you did it to the shocks the car would start moving in unwanted ways, much like your bridge did.
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Old 09-17-2004, 12:53 PM   #5
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the res freq of a car isnt a factor of the car so much as it is the res freq of the volume of air inside the car...

and honestly, if you get the box right to the vehicle, tuning doesnt make much difference.. but until then.. trial and error is the only way.. i normally tune at my peak note, but im usually tuned a hair too high... id rather go too high than too low...
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Old 09-17-2004, 01:13 PM   #6
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i recall 2 things for resonant frequency's last year with physics that seem pertinent here. One was a lab which used cylinders and tuning forks, and yes, at the resonant frequency of the cylinder, the sound was the loudest. The other thing was the movie with the bridge where the wind blowing through the valley and hitting the bridge at the resonant frequency of the bridge. In turn, the bridge began to sway and or vibrate at an exponential rate and the bridge collapsed into the river. Of course the cylinder example makes more sense in this case, but thinking of resonant frequencies always makes me think of the tacoma bridge
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Old 09-17-2004, 03:16 PM   #7
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well this depends on the amount of power yuo have on tap.

at tuning, the subs will move the least, and put out the most sound through the port. If you have enough power to over come the pressure and get the subs to xmax tuning is the loudest spot on the subwoofer. If you cant get it pumping that hard at tuning, i would suggest tuning the box a bit below where your car is loud, that way the extra cone movement will add to your loudness....
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Old 09-17-2004, 03:45 PM   #8
DD MAN

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the only thing that matters in SPL are waves it's just finding out what you have to do to get them correct
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Old 09-17-2004, 03:47 PM   #9
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well yeah, but the sub has to make them first.... you dont burp your woofers with 6kw 10 htz above tuning or youd prolly break em
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Old 09-17-2004, 03:49 PM   #10
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not really in ALL out SPL you basicly creatate the tuning freq to a certian extant. I can tell you right now that the res freq of my van is not 60 hz but thats where it is the loudest
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Old 09-17-2004, 03:58 PM   #11
ike 557

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Thanks for all the replys guys

I guess it's not gonig to be as easy as that. I'll have to just make an adjustable port and do some testing.


Thanks again

Matt
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Old 09-17-2004, 04:09 PM   #12
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Quote:
Originally Posted by DD MAN
not really in ALL out SPL you basicly creatate the tuning freq to a certian extant. I can tell you right now that the res freq of my van is not 60 hz but thats where it is the loudest
Thats wierd how it works out, seems with pressure the res. freq. changes. I dont know if it has to do with wave compression or what it is. SPL is such a wierd game. Getting the waves in phase is prolly one of the hardest parts of it all....
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Old 09-17-2004, 04:11 PM   #13
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one thing i have learned when it comes to spl...

get the following

1. large metal garbage can
2. lighter fluid/gasoline
3. matches
4. all of your box building programs
5. long stick
6. marshmellows
7. hershey's chocolate bars
8. gram crackers.

combine the 2 and 4 inside 1, then add 3.

place marshmellow on end of stick, roast over open flame(some perfer them burnt, some golden brown, it's up to you). place piece of chocolate on piece of grahm cracker. take smoking marhmellow(still on stick), place on top of chocolate. using another gram, place on top of marshmellow, remove stick. enjoy
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Old 09-17-2004, 04:13 PM   #14
itzvic

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best advice i heard all day.
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Old 09-17-2004, 04:39 PM   #15
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no no hot dogs and beer man
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