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NEED WinISD HELP! SA12 4th Order Box and Port Diminsions PLEASE??


bassR

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please tell me im doing something wrong, when I put in 1.2/2cu ft tuned to 45 with an 8 inch round port and 2 flared ends I'm getting 127" long?!! can that be right and obviously I can't get that length so what tradeoffs are avail to shorten that to something practical??

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An 8" port should be about 27.5" long to tune 2.0 cu ft to 45 Hz.  

As with all bandpass boxes I suggest making the port removable so the tuning can be adjusted after the box is playing.  Bandpass boxes can be fickle things.  

 

As far as the layout goes, that's always the hardest part with these things.  You may have to go with a slot port just so you can put bends in it to get the length you need.  

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

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  • 1 month later...

Sorry I haven't been on to keep you updated. Between life's regular curveballs I've only had a couple hours each week to dedicate to my interests without having the wife kill me and finish the box with me inside it, lol. So, before speaker and baffle displacement taken into account I'm at 3.472 cubes of internal space and should be pretty darn close to 1.2/2 with a round port that is 7.5" diameter with a 9" flare on each end and no common walls. I'll upload pictures of it as it comes together, however my question is how long the port needs to be to hit that magical 45 hz and how much distance needs to be between the end of the port and the back wall of the box?? The remainder of the port will be outside of the box to bring it into the cabin of the car... I'm so excited to hear this SA12 and wonder if the box will be the right size to later upgrade to a U or an X series Sundown...? One thing at a time I guess.

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21 hours ago, bassR said:

Sorry I haven't been on to keep you updated. Between life's regular curveballs I've only had a couple hours each week to dedicate to my interests without having the wife kill me and finish the box with me inside it, lol. So, before speaker and baffle displacement taken into account I'm at 3.472 cubes of internal space and should be pretty darn close to 1.2/2 with a round port that is 7.5" diameter with a 9" flare on each end and no common walls. I'll upload pictures of it as it comes together, however my question is how long the port needs to be to hit that magical 45 hz and how much distance needs to be between the end of the port and the back wall of the box?? The remainder of the port will be outside of the box to bring it into the cabin of the car... I'm so excited to hear this SA12 and wonder if the box will be the right size to later upgrade to a U or an X series Sundown...? One thing at a time I guess.

 

If your ported chamber is 2.0 cubic feet *net* your 7.5" port would need to be about 24" in effective length to tune to 45 Hz, keep a port clearance of about 7.5" to the wall, the internal end of the port should be located as far as possible from the driver.

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  • 2 weeks later...

years back, I had a 4th order design for a SA12. I wanted flat response and at the time I had a sedan with a ski hole. I was looking for the response graph but cant locate it, again several years back.  Here is what I could find. It was 2.0 sealed with a .075 ported section tuned to 60hz. Someone would have to model it again to also give you port size. The note I found was keep port fairly large but shoot for under 30 m/s at peak, again this was tuned at 60hz. From memory it modeled really well from 70 down. Again, maybe someone will be willing to model it again for you to see what I was given as  a design years back. 

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