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Question for all the SPL nerds...what's the theory on this?

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Old Apr 5, 2006 | 06:18 PM
  #1  
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Question for all the SPL nerds...what's the theory on this?

here is a scenario.....

i burp at 52hz (which is the best hz for the vehicle) and i get a number, say its 155 db's.

then i burp 55hz and the spl drops to 152 db's

then i burp at 49hz and i get 154 db's

my question is this. why does a frequency change of 3hz lower produce less spl lose than change of 3hz higher? should it not be same or close since the sin wave is a porabola? does this depend on the vehicle?

anywhere from 45 to 52hz i get small but steady increases in spl, can be as small as 0.2 db's increments from hz to hz. but, anywhere from 52 to 56 hz spl starts dropping fast as much as a full db from hz to hz.

can one of u nerds explain this.
Old Apr 5, 2006 | 06:20 PM
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... cause impedence rises faster after your boxes peak than before
Old Apr 5, 2006 | 06:48 PM
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Originally Posted by Lessy
... cause impedence rises faster after your boxes peak than before
... and the reaction of u'r vehicle to the pressure and its' resonant freq(s). If you can graph the resonance of u'r vehicle, it will not come out symmetrical.
Old Apr 5, 2006 | 07:47 PM
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what Lessy said ( impedance rise ) ... plus it has lots to do with wavelengths and cancelation
Old Apr 5, 2006 | 08:08 PM
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Agreed less MTA's Wavelengths.
Old Apr 5, 2006 | 08:45 PM
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i think u are all wrong
Old Apr 5, 2006 | 08:57 PM
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Originally Posted by Prolifik
i think u are all wrong
Remember it's a combo of box and car that makes it louder at X frequency.

Size and frequency both need to be tested to find loudest frequency.

But if you know everyone is wrong why are you asking?
Old Apr 5, 2006 | 09:13 PM
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ya... now build me my box!
Old Apr 5, 2006 | 10:41 PM
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Question

1st have you moved the box form when you did the 49-55 there is a lot more then just #hz

what was in the car ? like just you was the seat up

what you are asking is like i need a box made how big do i need it to be?


what car what amp ?
what box what is in the box(fill) ?
is it outside test is it sunny?
WHERE IS THE BOX ?
it the box ported?
is the box fastend down?
Old Apr 5, 2006 | 11:28 PM
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Originally Posted by Lessy
ya... now build me my box!
damm he builds boxes for you?

I have been trying to get him to build me one for a while now



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