# SDX12 in a 2.1 (ft3) .....help!!!



## Gioxtream (Mar 23, 2014)

I am not sure if this driver would behave well in a 2.1 ft3.

I have the bash 500 watts amp. Can someone help me model this driver in a net volume of 2.1 ft3?

Oh...!! I forgot....I have not include the displacement of the driver neither the volume of the 500 watts bash AMP.

I AM DYING TO SEE SOME MODELING CHARTS IF POSSIBLE FROM SOMEONE WHO REALLY KNOW THIS DRIVER.
I AM WILLING TO GO SEALED OF PORTED WITH ACURATE INFO.

THANKS.


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## Mike P. (Apr 6, 2007)

Here is 2 cu.ft. sealed compared to 2 cu.ft. ported.

The volume is the net volume of the cabinet, to that you add the displacement of the driver, amp, bracing, and any porting.

A 22 hz tuning frequency would require a 4" round flared port 32" long.


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## Gioxtream (Mar 23, 2014)

Mike P. said:


> Here is 2 cu.ft. sealed compared to 2 cu.ft. ported.
> 
> The volume is the net volume of the cabinet, to that you add the displacement of the driver, amp, bracing, and any porting.
> 
> ...


Hummmm. The QTC OF 0.565 is equal to what low frequency aproximayely?

Also this driver is dual coil....so Should I wire them like this:

+ with + and - with - ?

Will this port is the best one to avoid compression?

Any modification in the bash amplifier? 


Thanks one again.


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## Gioxtream (Mar 23, 2014)

Mike P. said:


> Here is 2 cu.ft. sealed compared to 2 cu.ft. ported.
> 
> The volume is the net volume of the cabinet, to that you add the displacement of the driver, amp, bracing, and any porting.
> 
> ...


I forgot to tell you the the deep of the driver when mounted is 8 inches. And the wide is when mounted flat is 21 inches.

Does the form of the internal volume matters?


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## Mike P. (Apr 6, 2007)

The port air speed is quite high with a single 4" flared port and 2 cu.ft. is too small for two 4" ports as they would need to be unrealistically long at 67" each.

Passive radiators would be a much better design. 


> _
> I forgot to tell you the the deep of the driver when mounted is 8 inches. And the wide is when mounted flat is 21 inches._



I'm not sure what you mean. Are you limited to a specific box size?
​


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## Gioxtream (Mar 23, 2014)

"The port air speed is quite high with a single 4" flared port and 2 cu.ft "

Do you mean that there will be no compression? Or I will have some?

I got no problems with the size a of the port you gave me. 

I just want to make sure everything goes accordenly the way it should. Also...Is there is some modifications procedures in the plate amp? What resistors o resistor should I use?
Also.....there is no ploblems conecting a DVC subwoofer with this bash amp right?


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## Gioxtream (Mar 23, 2014)

Mike P. said:


> The port air speed is quite high with a single 4" flared port and 2 cu.ft. is too small for two 4" ports as they would need to be unrealistically long at 67" each.
> 
> Passive radiators would be a much better design.
> 
> ...


Well...Passive radiators could be the best...but...I am stuck with an enclosure in the form of a letter L .

I mean the 2.1 ft3 enclosure has a form of a letter L. 
I am sure it has 2.1 ft3. That's why I asked if the form of my enclosure could be a problem.

You said that the air speed is quite high.....is this good? Or I would suffer compression?

Also.....what resistor should be applied on the BASH AMP TO MACH THIS DRIVER?

Thanks.


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## Mike P. (Apr 6, 2007)

The air speed is 28 m/s so there will be compression, hopefully there won't be port noise.

No modification are needed for the amp, use it as is.

The driver needs to be wired in series for a 4 ohm load to use with the amp.

You say the cabinets is 2.1 ft3, is that the net volume after deductions are made for the displacement of the driver, bracing and port?


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## Gioxtream (Mar 23, 2014)

Mike P. said:


> The air speed is 28 m/s so there will be compression, hopefully there won't be port noise.
> 
> No modification are needed for the amp, use it as is.
> 
> ...


No deductions of the amp space neither of the driver displacement has been made.So..... 2.1 net volume is what I have.

:-(


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## Gioxtream (Mar 23, 2014)

Gioxtream said:


> No deductions of the amp space neither of the driver displacement has been made.So..... 2.1 net volume is what I have.
> 
> :-(


What's the perfect ported volume for this driver and the perfect ports length and diameter?

I am wondering if I can get a carpenter to add extra volume to my boxes that's all.

Thanks so much.


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## Gioxtream (Mar 23, 2014)

Gioxtream said:


> What's the perfect ported volume for this driver and the perfect ports length and diameter?
> 
> I am wondering if I can get a carpenter to add extra volume to my boxes that's all.
> 
> Thanks so much.


Hummmmmm.

If I decide to go with a single passive radiator......could you recomend a better looking one than the css?


A link for a good passive radiator would be awesome.


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## Mike P. (Apr 6, 2007)

You would have a net intenal volume of about 1.7 cu.ft. and the port would be 30" long so porting is not realistic. I don't know what other PR's that would work. You should just go with a sealed design.


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## tundraSQ (Mar 17, 2007)

sorry to bimp this thread, just wondering if the OP ever built this box and how it turned out.

I am building almost an identical sized sealed box and was just looking for some input.

i figure after amp ,speaker and bracing are deducted from the volume, i will be at 1.6cuft of actual airspace.


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## calraith (Apr 13, 2014)

For a 1.6 net cubic foot sealed enclosure, you'll have a system Q a little over 0.6. I'd recommend going larger if you can, and try to get closer to 0.5. My box is 3 cubic feet, and stuffed with a pound of Poly-Fil it's right around 0.5. It's very responsive, and handles the opening bass tones of Edge of Tomorrow very well, retains the timbre of upright bass in jazz tracks, and handles a symphonic bass drum with transparency.

If you're interested in vented, you're looking at 2x rear-mounted 1.75" dia x 16 2/3" length ports for a port tuning of 21.2Hz. You can probably manage that going 7" in, 90 degree bend, and another 9" or so down. F3 will be about 25Hz, F6 about 20Hz, and the sub will average about 107dB from 30 - 80Hz at 250W. At 25Hz you'll have about 5dB more ouput with vented than with sealed. If nothing else, you could buy a couple of rubber corks and plug the ports whenever you want to try sealed. 

Not a bad system plan, but you give up a small bit of subsonic extension with the smaller size vented box. Be that as it may, it still graphs nicely in that size enclosure.










Notice the dip in the cone excursion centered right at the driver's Fs, and the symmetry between the peaks in the impedance graph with the center also at Fs. Those are a couple of indicators of a solid design.

If you prefer, you could use the CSS 12" passive radiator instead of ports, add eleven of the 45g washers for 495g of ballast, and end up with similar tuning (albeit with a sharper subsonic rolloff).

I think a 2.5cu.ft. box with two 2"x13.5" ports would be slightly better, having an F3 of 20Hz and less likely to require bends in the ports. But truth be told, there's only about a 2.5dB difference between the two at 25Hz, and you might never hear enough difference that it'd matter.


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