What if my port on my sub was bigger?

[cameron paterson]

I have a TC Sounds LMS-R Ultra 5400 18" subwoofer in a 7.3ft3 box after all displacements. It is tuned at 20hz. My port is 16" wide x 3" high. So 48 square inches. I don't get any chuffing even with test tones. Would my sub sound better or give more output if the port were substantially bigger? I know when you listen to an SVS PB16 Ultra and 2 of the ports are plugged the one port is still enough for it obviously so why would a bigger port help me?

 

[Verdinut]

If the port was made bigger, that would increase the tuned frequency of the enclosure and change the whole response curve. You would lose in low frequency efficiency and would also risk damaging the sub if you drove it with frequencies below the new box tuning frequency.
There is absolutely no valid reason to change the port dimension as designed by the manufacturer.

 

[cameron paterson]

I didn't mean change the ports on the SVS PB 16 ultra I meant make a new box for my TC Sounds 18" with a bigger port but still tuned @ 20hz. I was comparing the SVS PB 16 ultras ports by saying with 2 of the ports plugged only 1 port must be enough when running it like that. So my port must be big enough since its much bigger than the SVS's single port. Or even bigger than all 3 of the SVS's ports together.

 

[Verdinut]

You might get more output to a lower frequency, but that would have to be verified beforehand with a box building software such as BassBox. The improvement might be minimal and not be worthwile to proceed with.
A woofer driver is designed to perform at its best in a certain box volume based on its Thiele/Small parameters. Usually, the manufacturer will provide info about the optimum box volume for its drivers.

 

[cameron paterson]

I ran my box with winisd before I had the box made and its got a flat frequency response. I think its the perfect combo for music or home theater. I was thinking a bigger port wouldn't be worth building a new box.

 

[TLS Guy]

I have a TC Sounds LMS-R Ultra 5400 18" subwoofer in a 7.3ft3 box after all displacements. It is tuned at 20hz. My port is 16" wide x 3" high. So 48 square inches. I don't get any chuffing even with test tones. Would my sub sound better or give more output if the port were substantially bigger? I know when you listen to an SVS PB16 Ultra and 2 of the ports are plugged the one port is still enough for it obviously so why would a bigger port help me?

How long is the port? The port should be 31" long for that size opening in that box. If those are the dimensions you have then the vent air velocity is 22 m/sec, which is correct and will not chuff.

That gives you an F3 of 27 Hz. That driver does not go particularly deep. It is a high spl sub.
The optimal cox for tightest base is 3.5 cu.ft. Correctly ported your box is an extended bass alignment, which lowers F3 from 34 Hz optimal box to 27 Hz with your alignment. So not a lot of extension.

If you made the port bigger then you would get into port resonance issues to no purpose as there is no point on lowering the vent air velocity further.

I hope this is a properly tunneled port as if that is just an opening, then you have a real mess on your hands, that can not even be calculated.

 

[cameron paterson]

The guy who made the box for me has made hundreds of boxes he did everything perfect. 1" MDF and very well braced as well! The port is 16" x 3" x 39" long. With 7.3ft3 internal volume after all displacements. That's what the subwoofer enclosure calculator has it at.

 

[TLS Guy]

The guy who made the box for me has made hundreds of boxes he did everything perfect. 1" MDF and very well braced as well! The port is 16" x 3" x 39" long. With 7.3ft3 internal volume after all displacements. That's what the subwoofer enclosure calculator has it at.

By Bass Box Pro the port is 8" too long.

 

[cameron paterson]

Go to this website and plug in the port size and size box.
https://www.the12volt.com/caraudio/boxcalcs.asp

winisd also says 39"