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1 vs 2 ports, differences

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XxAndreaxX

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Just a question, I transformed my sealed sub into a ported sub. calculated the port diameter and the port lenght. everything fine, except at 30% volume, you start hearing some air moving. at lower freq and higher volume, its very annoying. so I wanted to build one more port.

whats better, 1 bigger port, or 2 small ports??

if I decide to put another port, do I have to change something at the port lenght??

thanks!!

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Yes you need to adjust the length if you add a second port

Too little port area will cause port noise at lower frequencies

Find the internal volume in cubic feet of the box then multiply it by 10

That is a good start for the area of port you need

Then use an online calculator to find the port length

 

---------- Post added at 01:34 PM ---------- Previous post was at 01:33 PM ----------

 

It would be best to keep as much of the port out of the box as possible to not use up tons of internal volume

 
Yes you need to adjust the length if you add a second portToo little port area will cause port noise at lower frequencies

Find the internal volume in cubic feet of the box then multiply it by 10

That is a good start for the area of port you need

Then use an online calculator to find the port length

 

---------- Post added at 01:34 PM ---------- Previous post was at 01:33 PM ----------

 

It would be best to keep as much of the port out of the box as possible to not use up tons of internal volume
Click to expand...
the problem is that the calculator changes from 20cm for single port lenght, to some meters for 2 port lenght.... I don't have place for a meter for each port...

I'll try with 2x 20cm ports and see how it sounds and how its tuned.

 
The larger the port the longer it needs to be to lower tuning

Post your box dimensions and what port you are trying to put in

It is not uncommon for a port to be 25-30" long

 
The larger the port the longer it needs to be to lower tuningPost your box dimensions and what port you are trying to put in

It is not uncommon for a port to be 25-30" long
Click to expand...
the box is totally uneven, so i can't post exact dimensions. i only know its 10l capable, minus the speaker itself. its a sundown X8 so quiet big speaker for such a small enclosure. results of port were something like 20-25cm long tube for 4cm diameter. obviously too small for all that air, but 5cm resulted in something like 50cm and 6 was over a meter.

 
the box is totally uneven, so i can't post exact dimensions. i only know its 10l capable, minus the speaker itself. its a sundown X8 so quiet big speaker for such a small enclosure. results of port were something like 20-25cm long tube for 4cm diameter. obviously too small for all that air, but 5cm resulted in something like 50cm and 6 was over a meter.
Click to expand...
Your whole box is too small to begin with. You cant expect to port a sealed box and think it'll work. It will not work whatsoever. Almost all of the times ported boxes HAVE to be MUCH bigger than sealed boxes. Its just how its meant to work, it just works that way physics wise. If its not big enough you are strangling the sub and killing any chance it has to get loud or sound good along with cause port noise as well.

here's an example of a box in metric system with centimeters and liters thats of proper size, port is still kind of small to be honest but it should work.

If you really want to port a box, find a 12 inch or 10 inch subwoofer box and make a baffle for your 8 and then port those boxes. They have a much better chance of being big enough than a sealed 8 inch box. Your sub is too nice to be put in a junk designed box thats choking it for air.

6Ik5EK.jpg


in imperial system it comes out to be .76 usuable cubic feet around 9 port area per cubic feet with a 3 inch diameter port for you american guys that dont know conversions.

 
Your whole box is too small to begin with. You cant expect to port a sealed box and think it'll work. It will not work whatsoever. Almost all of the times ported boxes HAVE to be MUCH bigger than sealed boxes. Its just how its meant to work, it just works that way physics wise. If its not big enough you are strangling the sub and killing any chance it has to get loud or sound good along with cause port noise as well.
here's an example of a box in metric system with centimeters and liters thats of proper size, port is still kind of small to be honest but it should work.

If you really want to port a box, find a 12 inch or 10 inch subwoofer box and make a baffle for your 8 and then port those boxes. They have a much better chance of being big enough than a sealed 8 inch box. Your sub is too nice to be put in a junk designed box thats choking it for air.

6Ik5EK.jpg


in imperial system it comes out to be .76 usuable cubic feet around 9 port area per cubic feet with a 3 inch diameter port for you american guys that dont know conversions.
Click to expand...
thanks bro!! I'm not american, so I'm familiar with metric. the whole problem is that I can't play with the size of the box. my car is very tiny, and the size of the box is given, I can't change it. Now, as far as porting it, everyone told me not to port it. but I did it, and it sounds muuuuch louder than before. I lost some SQ, but it was necessary. now my goal is to get rid of the air noise, without sacrificing SQ or SPL

 
x8's work better ported than sealed....if you have this sub. I don't think sealed is recommended for the driver.
@CSCStang could prob help ya with a box design if yuor interested.
 
thanks bro!! I'm not american, so I'm familiar with metric. the whole problem is that I can't play with the size of the box. my car is very tiny, and the size of the box is given, I can't change it. Now, as far as porting it, everyone told me not to port it. but I did it, and it sounds muuuuch louder than before. I lost some SQ, but it was necessary. now my goal is to get rid of the air noise, without sacrificing SQ or SPL
Click to expand...
you cant have one or other other...

"small box size, SQ, or SPL you can only pick two" a common car audio quote.

 
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