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Discussion Starter · #1 ·
I have a 12" TC Sound Epic, got it of partsexpress on buyout last year. I have a ported box and sealed one for it. The ported one is about 3cu.ft, with an 4 inch port about 17inches long, flared on both ends. My sealed box is about 1.7cu.ft. I don't quite understand why the sealed one goes lower and louder. Do I need to make a larger ported box and tune it lower?
 

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How do you know that it goes 'lower and louder'? Have you taken measurements? In general, a sealed box will have a more gradual roll off vs a ported box. A properly designed port will give you a boost at lower frequencies at the cost of some bass extension. You need to model your driver in software and determine what the ideal enclosure is going to be. You may be able to modify your existing enclosures or you may need to start from scratch (depending on your overall design goals).
 

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Discussion Starter · #3 ·
I used WinISD when designing both, and an SPL meter to check the results. From 16 hz to about 23 the sealed is 10 db louder, after that its between 2-6 up to about 56 hz.
 

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If it is louder at and above the tuning of the ported enclosure then my guess is that yes, you do need to go larger.

Below tuning point the sealed could/should be louder as the roll off is slower.


What does WinISD say is your F3 for your ported enclosure?
 

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then below that the sealed would be better.

But above that it should be equal subject to subjective listening, if not advantage ported.

Can you post a picture of the graph?
 

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Discussion Starter · #9 ·
Well I think I'm just going to build another ported. About 4.6 cu.ft. tuned to 19hz.

Going to make just a tad bigger version of the PB12-NSD
 

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Quote:
Originally Posted by kmlm13 /forum/post/15574585


Well I think I'm just going to build another ported. About 4.6 cu.ft. tuned to 19hz.

Going to make just a tad bigger version of the PB12-NSD

Stick with the sealed.


Kg
 

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Discussion Starter · #12 ·

Quote:
Originally Posted by kgveteran /forum/post/15576345


Stick with the sealed.


Kg

Why?? Plus, during Hulk(the new one), I heard one of the speakers clipping or the voice coil hitting something. The scene in the field wih the speaker hummers.
 

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Quote:
Originally Posted by kmlm13 /forum/post/15577030


Why?? Plus, during Hulk(the new one), I heard one of the speakers clipping or the voice coil hitting something. The scene in the field wih the speaker hummers.

In a ported box without a subsonic filter, it could have been worse....much worse. Below the tuning frequency driver excursion becomes uncontrollable as opposed to sealed where the driver excursion is controlled by the air cushion inside the box...simplified a bit. In the sealed box if you're bottoming either the box is too big or too much power to the system. Can you post the drivers T/S Parameters?
 

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Discussion Starter · #14 ·
Specifications: *Power handling: 600 watts RMS *VCdia: 2" *Le: 2.49 mH *Impedance: 2 ohms per coil *Re: 4.2 ohms (coils wired in series) *Frequency range: 21-500 Hz *Fs: 21 Hz *SPL: 89.3 dB 2.83 V/1m *Vas: 4.66 cu. ft. *Qms: 4.25 *Qes: 0.41 *Qts: 0.38 *Xmax: 22 mm


The sealed box is bit bigger than recommended by winisd, but the difference is really negligible, and it only happens when there is some really low bass. It seems more like I might be pushing it too hard, but if I turn it down it doesn't match with the other speakers, and I lose on bottom end.
 

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depending on how loud you are playing the ported version, you may have too small of a port. at the tuning frequency, pretty much all the sound of the ported system is blowing out the port. a single 4" port may be too small and thus limiting your output around the tuning frequency. that's the only thing that i can think of that would result in a ported version having lower spl than a sealed version. the ported version should be kicking out 4-6db more than the sealed around the tuning frequency.
 

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Quote:
Originally Posted by LTD02 /forum/post/15580222


depending on how loud you are playing the ported version, you may have too small of a port. at the tuning frequency, pretty much all the sound of the ported system is blowing out the port. a single 4" port may be too small and thus limiting your output around the tuning frequency. that's the only thing that i can think of that would result in a ported version having lower spl than a sealed version. the ported version should be kicking out 4-6db more than the sealed around the tuning frequency.

Yeah, a single 4" port seems a bit small for a relatively high excursion 12. Though I would like to see how it models out in a bigger box. I'm at work or else i'd take a look.
 

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Quote:
Originally Posted by kmlm13 /forum/post/15577030


Why?? Plus, during Hulk(the new one), I heard one of the speakers clipping or the voice coil hitting something. The scene in the field wih the speaker hummers.

Even great drivers bottom out. The idea when researching a build is to find out what spl will be needed at the listening position.I know we beat up SPL's but it is what it is. Bottoming and clipping are big NoNo's. To avoid this get with the number crunchers...measure how many feet away the sub is from the listening position.


Kg
 

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Discussion Starter · #19 ·
The sub is about 10 feet away in, front left corner. I modeled a larger ported with winisd and it looks pretty promising. Its just a tad bigger than the svs PB12-NSD.
 
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