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Stuffing Ported Sub (1 Viewer)

Daniel T

Stunt Coordinator
Joined
Jan 26, 2002
Messages
93
I have an Infinity BU2 sub that has an 100 watt amp, 12" downfiring sub, and a 4" cardboard port wiht flared end on the side. I want to build a Shiva or Tempest sub but I just purchased a Parasound 855 amp and my wife would kill me. I plan to build the DIY at the end of the year when the new amp purchase has been forgotten. I was wondering what I could do to maybe help improve the sound from my current sub. I have read alot about stuffing the sub but was wondering what is the proper way to stuff a ported sub. I know you are not suppose to block the port and the woofer with stuffing. Should I put some stuffing on the side and on top part of the inside of this sub. Would I get any benefit from replacing the cardboard port with a plastic port. I would like to improve this sub as much as possibe for a temporary fix. All suggestions are greatly appreciated.

Daniel T
 

Daniel T

Stunt Coordinator
Joined
Jan 26, 2002
Messages
93
If anyone has stuffed their ported sub, I would love to know if it worked or if it is a waste of time. I know someone on this forum must have tried this. Any help would be greatly appreciated.

Daniel T
 

Dustin B

Senior HTF Member
Joined
Mar 10, 2001
Messages
3,126
Stuffing an enclosure increases the apparent volume of the enclosure to the driver. In turn this will decrease the tuning frequency of the port. The smaller the enclosure the more effective stuffing will be at increasing the apparent volume of the enclosure.

Tom Nousaine has a paper that showed 1.5 lbs/ft^3 produced the largest increase for 1-3ft^3 enclosures. Once he started getting to larger enclosures the stuffing had less effect and he saw no point in more than 1 lb/ft^3. This however was more for sealed enclosures than ported ones, as it is very difficult to get that density of fiberfill in a ported sub and not impead the flow of air in the port.

The second thing stuffing can do is absorb higher frequency sounds that get into the sub. Either through the crossover or for various other reasons from cheap drivers.

Stuffing a cheaper commercial sub will decrease the tuning (they are almost all tuned too high, including some quite expensive ones), Q, and absorb some of the undesirable higher frequencies that get into it. But a properly built Shiva will destroy the Inifinity. As you won't make it too small, too flimsy or tuned to high with too small a port.
 

Chris Tsutsui

Screenwriter
Joined
Feb 1, 2002
Messages
1,865
One word of advice, don't stuff the ported sub with small chunks of polyester fill. Otherwise you'll see small balls flying out of the ports as you play different music.

My hands arn't long enough to put them back inside so I have my little sister do it. Hehe

Instead, just fluff big parts and just make sure that the stuffing isn't clogging the port. Air can still pass through the polyfil, just not as much when it's packed in the port.

The polyfill basically simulates increasing the baffle size. Once your sub is filled put your ear towards the baffle and you'll notice it absorbs ambient noise and you won't hear a thing.
 

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