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Ok so we pulled the trigger did two U 10’s D4’s on a sae 3k in one of the D4S pro fab pre fab boxes ... box is said tuned to 32hz , ok that’s befor any said sub displacement is calculated. With the two U 10’s that’s 0.42 of displacement that’s moving the box tuning up to about 35.5hz ! I see sundown website says 32hz l is what’s recommended. Should we do poly fil in the box?  If so how much to take away the displacement of the subs? Do not want to invert the subs at all. 

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And I don’t think the frequency will change that drastically. The frequency change will be minimal. The only way to take out displacement variables is to invert the subwoofers and change the polarity of the subwoofers by wiring positive as if it were negative and negative as if it were positive. Or if you invert your subs you can reverse the phase instead, 180. Never change the polarity and reverse the phase. Do one or the other. Changing polarity would be my choice. But to be honest with you, it’s best to keep the subs regular loss a little bit of airspace because of displacement and gain a little bit of frequency rise because of displacement. You will not hear any difference like you think you will. It won’t be audibly noticeable, even to audiophiles. Very minimal differences. 

Edited by 121gigawatts

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I would never have a port firing upward unless it was a last resort and I was pressed for space and had no other choice. So no, never have the port firing up. If the back seats in your car pull down to allow access to your trunk then have the subs and port firing back towards the front seats. If the seats don’t pull down then have the subs and port firing forwards towards the hatch of the trunk. 


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24 minutes ago, 121gigawatts said:

I would never have a port firing upward unless it was a last resort and I was pressed for space and had no other choice. So no, never have the port firing up. If the back seats in your car pull down to allow access to your trunk then have the subs and port firing back towards the front seats. If the seats don’t pull down then have the subs and port firing forwards towards the hatch of the trunk. 

The Scion tC is a hatchback that’s why I was thinking sub/port up at the glass vs toward the rear of car but most people say will not sound as good idk.

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Have it firing towards the hatch. If the width of the port is 4” then the enclosure must be at least 4” from the hatch for good air flow. If not, which I think you will have enough room to have it firing towards the hatch, then have it firing upwards towards the window. But leave that as a last resort. You will get more spl if you have the enclosure firing towards the hatch. Even if you’re an inch or so shy of making clearance then still keep it facing towards the hatch. Towards the hatch will always generate the most SPL. 


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the customer isn’t always right.”

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Closer to the hatch door without being closer than the width of the port the better but not closure to the widow facing up the better. Because sound waves bounce off surfaces and if they bounce off the direct back of the hatch they will bounce forward creating a good and hard hitting sound. If they bounce off the window they will the bounce towards the hatch floor then back up towards the front which creates more sound wave travel, thus less bass and worse sound. 

Edited by 121gigawatts

:stupid:“How can we help you?”
:+1:
 
“And don’t forget to tell them that 
the customer isn’t always right.”

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