Resonant Frequency Results....

[dleccord 5,000+ posts]

So I made a mock up of a sealed box I'm planning to build purely for SPL and ran a sweep for my pick-up truck. I peaked at 53hz and my highest score was 131.x dBeez. I believe my truck peaks in the high 50s or low 60s region. Can not having enough power give wrong readings?

BTW: DD9500s **** in sealed boxes. seriously.

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[skadude016 5,000+ posts]

So I made a mock up of a sealed box I'm planning to build purely for SPL and ran a sweep for my pick-up truck. I peaked at 53hz and my highest score was 131.x dBeez. I believe my truck peaks in the high 50s or low 60s region. Can not having enough power give wrong readings?
BTW: DD9500s **** in sealed boxes. seriously.

well did the woofer reach its full excursion?

 

[robertspangler 10+ year member]

lol im glad i didnt put mine in a sealed box becuase i was going to

 

[dleccord 5,000+ posts]

well did the woofer reach its full excursion?

yeah excursion was at least an inch, i believe, if not more.

 

[skadude016 5,000+ posts]

yeah excursion was at least an inch, i believe, if not more.

1-1.25 standard cubic foot box? if so that should be your peak freq. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[dleccord 5,000+ posts]

my sealed box was about 4.3 cubes. i figure it should be that big since my next box is going to be that big and that shape so cabin space will be the same or close.

 

[skadude016 5,000+ posts]

my sealed box was about 4.3 cubes. i figure it should be that big since my next box is going to be that big and that shape so cabin space will be the same or close.

I would just build a 1-1.25 size box and find stuff to take up the extra room around the box //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Immacomputer 10+ year member]

That's not really a good way of finding your peak for a ported enclosure. If you wanted to get a little closer, measure the frequencies from about 45-65hz with the box in the vehicle and then out of the vehicle. Subtract the two plots and you will have a ghetto transfer function. It will be slightly more accurate than what you did.

 

[dleccord 5,000+ posts]

whats the difference between the smaller 1.5 cubes vs the 4 cubes sealed enclosure?

 

[skadude016 5,000+ posts]

whats the difference between the smaller 1.5 cubes vs the 4 cubes sealed enclosure?

well one is gonna have alot more bottom end

 

[young_gun 10+ year member]

My single cab peaks in the mid 50s fwiw

 

[GemaRastem 10+ year member]

I would personally build a perfectly flat .707 box which the size is going to depend on the woofer you are using, and then run the sweep. Using a .707 box means that it has a flat frequency response which means when you run the sweep, your highest frequency is going to be the actual resonant frequency of the car

 

[Immacomputer 10+ year member]

I would personally build a perfectly flat .707 box which the size is going to depend on the woofer you are using, and then run the sweep. Using a .707 box means that it has a flat frequency response which means when you run the sweep, your highest frequency is going to be the actual resonant frequency of the car

That's not true. The .707 alignment is the max flat alignment for the driver in the enclosure. It does NOT mean a perfectly flat frequency response.

If he wants to get a better idea of the resonant frequency, he needs to measure the enclosure out in an open area at the same volume levels and over the same frequency that he measured in the car. That is the true transfer function.

 

[snoopdan 5,000+ posts]

why dont you just do a few test dones at full volume on your normal box and just do a process of elimination of what fequency yeilds the highest SPL number? There are so many variations of loading methology / resonance / pressurization of the cabin that its kinda silly to test anything but the sub/box combo you intend to compete with....or whatever you're going to do with it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[dleccord 5,000+ posts]

That's not true. The .707 alignment is the max flat alignment for the driver in the enclosure. It does NOT mean a perfectly flat frequency response.
If he wants to get a better idea of the resonant frequency, he needs to measure the enclosure out in an open area at the same volume levels and over the same frequency that he measured in the car. That is the true transfer function.

what's the significance of finding the resonance frequency of the enclosure outside the vehicle? with the results measured from inside/outside the cabin, what am i looking for?

why dont you just do a few test dones at full volume on your normal box and just do a process of elimination of what fequency yeilds the highest SPL number? There are so many variations of loading methology / resonance / pressurization of the cabin that its kinda silly to test anything but the sub/box combo you intend to compete with....or whatever you're going to do with it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

ill keep this in mind.

btw... do you think 1inch of concrete will be strong enough for a back wall for a single 15 inside a 3.5 cubic foot enclosure?