Port area is 18 in^2 per cube..

[Never Enough Bass]

That's where your subsonic filter comes in play

[Never Enough Bass]

My port area is 3.5×14×29.9

[Never Enough Bass]

Tuned at 32hz

[Never Enough Bass]

In a 4 cu box

[Kyblack76]

2 hours ago, whoopdeedoo said:

The tuning is fine. I'm more concerned with the port area being too big. Could cause the sub to bottom out among other things.

 

 

Then shrink it. And gain volume. 

[whoopdeedoo]

8 minutes ago, Kyblack76 said:

 

 

Then shrink it. And gain volume. 

Should I just throw it in the dryer on hot?

[Triticum Agricolam]

2 hours ago, whoopdeedoo said:

The tuning is fine. I'm more concerned with the port area being too big. Could cause the sub to bottom out among other things.

No, that's not how it works.  You will most likely be fine.  

 

The whole concept of "16 sq in per cube" is an oversimplification.  There is a number of factors that go into how big your port should be for optimal performance.  Things like input power, tuning frequency, etc.  

 

It actually pretty hard to have a port that's too big.  At 18 in per cube I can almost guarantee it won't be too big.  Too small is where most people get into trouble.  

[whoopdeedoo]

5 minutes ago, Triticum Agricolam said:

No, that's not how it works.  You will most likely be fine.  

 

The whole concept of "16 sq in per cube" is an oversimplification.  There is a number of factors that go into how big your port should be for optimal performance.  Things like input power, tuning frequency, etc.  

 

It actually pretty hard to have a port that's too big.  At 18 in per cube I can almost guarantee it won't be too big.  Too small is where most people get into trouble.  

Thank you

[SnowDrifter]

The whole port area/cuft thing is.... Really just a super loose rule of thumb for base-level box head-math tbh.


Actual port area is primarily dependent on port velocity (chuffing), with influences based on power, tuning, and port dimensions. In particular: Boundary layer flow behavior. That's why things like aero ports can get away with less port area than a simple slot port - because the circular profile minimizes surface area relative to port area, which consequently also provides the greatest distance from wall-to-center-of-port.

On the other extreme, you could have a box with 40in^2/cuft but if it's just a big ass half inch wide L port.... It'll sound and perform like doodoo.

The other piece to port area, is while a smaller port might be more resistant to chuffing, and perhaps some efficiency losses, it won't unload as quickly when playing below tuning, and also won't have nearly as strong of a peak at tuning. That was one of my little 'hacks' when I had a system in my old car... had some aero ports with some port plugs (not to be confused with bu--) I'd use to drop tuning and port area for a play-anything daily listen. The box had a ridiculous bandwidth for just a basic ported enclosure... 17hz up to around 65 (though I usually kept my LPF low around 45, just as personal preference).

If you want to post equipment and box specs (tuning, size, physical port/box dimensions) we could give you some better guidance.

[whoopdeedoo]

On 10/8/2021 at 9:40 AM, SnowDrifter said:

The whole port area/cuft thing is.... Really just a super loose rule of thumb for base-level box head-math tbh.


Actual port area is primarily dependent on port velocity (chuffing), with influences based on power, tuning, and port dimensions. In particular: Boundary layer flow behavior. That's why things like aero ports can get away with less port area than a simple slot port - because the circular profile minimizes surface area relative to port area, which consequently also provides the greatest distance from wall-to-center-of-port.

On the other extreme, you could have a box with 40in^2/cuft but if it's just a big ass half inch wide L port.... It'll sound and perform like doodoo.

The other piece to port area, is while a smaller port might be more resistant to chuffing, and perhaps some efficiency losses, it won't unload as quickly when playing below tuning, and also won't have nearly as strong of a peak at tuning. That was one of my little 'hacks' when I had a system in my old car... had some aero ports with some port plugs (not to be confused with bu--) I'd use to drop tuning and port area for a play-anything daily listen. The box had a ridiculous bandwidth for just a basic ported enclosure... 17hz up to around 65 (though I usually kept my LPF low around 45, just as personal preference).

If you want to post equipment and box specs (tuning, size, physical port/box dimensions) we could give you some better guidance.

Was away for a while sorry for the late response.

 

(2) 15" PSI 1 ohm dvc 1000rms subs running in series-parallel at 1 ohm on a CAB-22 2200 rms. Subs up port back. Port runs along the right side of the box. 1/0 gauge power/ground.

 

Box dimensions: External 48" Wide by 28" Deep by 17" High.

MDF is .75" and its double baffle so Internal should be 46.5 x 26.5 x 14.75.

Port Internal: 9.75" Wide x 14.75" High x 28.25" long. If my math is right its 10.5 cu.ft. inside the enclosure minus 2.35 cu.ft. of port and .28 cu. ft. for the drivers, the subs are seeing 7.87 cu.ft. The box has 45'd corners but idk how much those are displacing, they aren't very big.