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Discussion Starter #1
Need to know what port lengths to use for a ported SDX12? I emailed CSS about the idea of using a SDX12 in the DIY sound group 4 cuft flat pack and it looks like it would work pretty well using the Dayton SPA1000. Would like to have it tuned around 15-18hrz or whatever the HPF is on the off the shelf Dayton SPA1000.

Kind of gathering different DIY options for mostly hometheater and while I thought I was set on dual 15"s sealed I just keep coming back to XBL2 options to match the Arx XBL2 setup. Super impressed with XBl2 and a 1000 watt ported SDX12 might be one powerful option for hometheater.
 

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I love my SDX15 ported set. They have truly amazing sound. I was going to try and help with the lengths, but can't find the file for winISD, but when I find it I can run it.
 

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I know CSS said in the email they model it for me and said 4cuf ported works great and works perfect with the SPA1000 HPF around 16-18hrz but they never told me what port lenghts to use or what lenghts they used for the model. The flat pack uses dual 3" ports.
 

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OK, my modeling skills in winISD are horrible, but for a tuning of 18hz, I come up with two 3" and 27" long round ports with your 4 cubes box, and 1000w with a LR HPF at 18hz giving you a port air speed of 24 m/s, 1st resonance at about 250hz.
 

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I thought I finally had it figured out! I added a HPF to the model and it lowered the air speed quite a bit. Is that where I messed it up Mike?
 

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Discussion Starter #7
Somethings not quite right with your modeling. 2 four inch flared ports 40 inch long each would tune the cabinet to 20 hz and the air speed would be 28 m/s peak.
The flat pack I want to use is this one http://www.diysoundgroup.com/subwoofer-flatpacks-2/ported-subwoofer-flatpacks/4-ported-sub-flat-pack.html

It has cutouts for dual 3" ports, so maybe the air speed will be too high with that small of ports?

Heres my email I got when I asked about the 4cuft flat pack:

Here is Jeff Bagby response:

Yes. It will work. I was skeptical at first, because the box is too large
for the woofer, and when modeled in this size box there is peak in the
response at 18-20Hz. However, if a plate amp is used that has a subsonic
high-pass in this region it flattens the response out very nicely. It looks
especially nice with the Dayton 1000 Watt amp. With it is flat to about 16hz
and with the 1000 Watts it hits 25mm of peak excursion, which makes good use
of the driver. It really is an ideal combination. The other sub amps looks
good too, but this design needs a subsonic filter in the 16-20 Hz range to
control the cone.

Thanks
Bob



But they never mentioned what port lenght they used.
 

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Hi i am also interested in a ported sdx 12 with dayton 1000 watt amp..but i have the option to build my box..what is the best size box for this set up.for the deepest bass responce..would slot port be better..any help with the desing of the box would be grealty apreciated.. and i also want ot design one for the sdx 10 with a css pa 500 watt amp.. help needed please..
 
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