Round Ports or Slotted Ports

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03-29-2005, 03:15 PM

sleboda

50 Watt CAFz'r

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Join Date: Apr 2004

Posts: 117

Okay I've always built whatever volume required and used round ports with the correct length for tuning (info supplied with sub manual).

I'm building a box for a JL 12 W3 v1 (dual 6 ohm), and I'm just looking at the specs and it says to build a Slotted ported box and inside the box the port actually follows the exterior wall (turns "l-shaped").

I'f I just figure out the volume needed can't I just use the same volume for a cylindrical port. Also if the port needs to be slotted can I build the box with one wall angled to match the angle of say the rear seat so this slotted port inside would also go on an angle when it turn's 90 degrees (to the "L shaped") design ...If I keep the same volume of the slotted port.

Should I just stick to the manual and build a Simple Square box with "L-shaped" internal slotted port.

What do the experts on this fine forum have to say?...lol

Thanks to any answers, questions and helpful advice.

03-29-2005, 05:15 PM

Paul Niwranski

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THe shape of the box and the vent don't affect the sound very often so do what fits the car.

If you indeed change from the slot to a round vent you need to keep the Area the same and the Length the same. Don't just use the 'volume' as you could have a shorter port with more area that will tune much higher or a longer port with less area that tunes much lower.

03-30-2005, 11:40 AM

sleboda

50 Watt CAFz'r

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Join Date: Apr 2004

Posts: 117

So I just make sure the area (cross section of the slot) and the total length are the same and I should be fine...?

For example if the Slot area is 10 sq in. and the length of the slot port is 14 inches. I could have a round port with an equal area of 10 sq in. and a total length of 10 sq in.

Now Could I have two rounds ports (like if I had to do two 2.5 inch diameter round ports instead of one 4 inch diameter port) at half the lengths?, so I'd have 2 round ports at 7 inch lengths?

Just trying to be exact!...lol

Thanks again.

03-30-2005, 01:16 PM

Paul Niwranski

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Again - if the area of the vent is the same, the length will be the same.

To get a shorter vent you have to reduce the area of the vent, increase the volume of the box, or tune to a higher frequency - all of which affect overall performance.

03-31-2005, 09:49 PM

Y2K-SS

50 Watt CAFz'r

Join Date: Oct 2002

Posts: 306

Is there not some software that will take the box's dimensions and the driver specs and give a general port size and lenght recommendation.
I remember making a home sub enclosure using an application like that, and it worked great, i will try to remember the name.

I personaly like square ports. gives the box more corner loading.

04-01-2005, 04:37 PM

sleboda

50 Watt CAFz'r

Thread Starter

Join Date: Apr 2004

Posts: 117

So you like the strength of the corner then?

I just look at it as...it's the box if built solid...any opening, whether it be, a round port or a slotted one...The purpose is to push the air though that port and to amplify?...the sound. If the volume is the same the sound should be the same...in theory, But I suspect the shape of the port...will obviously be different. It's all to the ears of the listener isn't it?