Port Area Clarification

[Cj Kumz]

Could someone please verify if that minimum port area calculation is for any box size. In our hdc3 example will that port area be the same in a 3, 4 and 5 cube box

[alaskanzx5]

Would it be safe to assume that with more box volume you can use a slightly smaller amount of port area?

I mean you need pressure inside the box for cone control. A big no with a big port gives less control. A big box with a say a 10% smaller port could give a little bit more pressure inside the chamber.

Just a theory here.

[Joe X]

I guess I understand what you are trying to say, the Small's estimate is based on the mechanical displacement of the sub (+ tuning) and will work under any box size, power, etc. It's true however everything else being equal larger net volume result in larger peak excursion so Small's estimate is a one size fits all and in many applications is space inefficient or plain not feasible.

[Cj Kumz]

Thanks a lot. I really needed that cleared up. Ok so do you guys think its worth it to build a new enclosure for my hdc315. Currently in a 4 cube box @ 36hz with 64sq inches. Calculator shows I need above 100 sq inches

[Triticum Agricolam]

Thanks a lot. I really needed that cleared up. Ok so do you guys think its worth it to build a new enclosure for my hdc315. Currently in a 4 cube box @ 36hz with 64sq inches. Calculator shows I need above 100 sq inches

Are you using the SAZ-3500d in your sig to power it?

I don't know if it would be worth it or not. I guess it depends on how much you like to build boxes. If it were me I would build it, just to see the difference it makes, but I like to build stuff. If you are putting all 3500 watts or moe into that thing I think you will see some benefit, but I don't think it will be a dramatic difference. If you aren't using all the power, you probably won't see much difference.

Also to comment on what alaskanzx5 and JoeX said. On larger boxes, if anything, you would want a slight larger port since you have a larger volume of air that is being manipulated to move in and out that port. By making the port smaller to try to gain cone control you are relying on air resistance, which is not what gives ported boxes cone control. Cone control comes from the air spring effect you get from the mass of air inside the port. If you made the port smaller I think you would just run into port compression, which would restrict cone movement, but would kill output.

[Jessica]

I don't understand how power is a factor. I mean if you build a larger port because you have more power how will the box perform at lower volume.

If you are building a box for pure SPL I think it would make sense.

Someone want to explain this?

[la negra]

I am under the influence that the port area of 9-10 will be more musical setup and 11-12 for spl numbers .

[CleanSierra]

I am under the influence that the port area of 9-10 will be more musical setup and 11-12 for spl numbers .

You're under the wrong impression then. You satisfy the driver's needs(cone area and Xmax), as well as desired tuning frequency.

You guys are over thinking this box volume to port area ratio. All you're doing is effectively tuning a plug of airspace, simple as that.

[Cj Kumz]

Thanks a lot. I really needed that cleared up. Ok so do you guys think its worth it to build a new enclosure for my hdc315. Currently in a 4 cube box @ 36hz with 64sq inches. Calculator shows I need above 100 sq inches

Are you using the SAZ-3500d in your sig to power it?

I don't know if it would be worth it or not. I guess it depends on how much you like to build boxes. If it were me I would build it, just to see the difference it makes, but I like to build stuff. If you are putting all 3500 watts or moe into that thing I think you will see some benefit, but I don't think it will be a dramatic difference. If you aren't using all the power, you probably won't see much difference.

Also to comment on what alaskanzx5 and JoeX said. On larger boxes, if anything, you would want a slight larger port since you have a larger volume of air that is being manipulated to move in and out that port. By making the port smaller to try to gain cone control you are relying on air resistance, which is not what gives ported boxes cone control. Cone control comes from the air spring effect you get from the mass of air inside the port. If you made the port smaller I think you would just run into port compression, which would restrict cone movement, but would kill output.

Thanks for that great info. I seem to be getting your point. I'm actually running my saz-3500d @ 2ohms(dual 1ohm sub) so that's about 2000w but 800w after rise. On Saturday I tried it at 0.5ohms and it sounded amazing but like air flow was restricted. So with your info my experience kinda makes sense. I should be getting another 15 when I get a bigger car (had to sell my other cause I eliminated the backseat and my wife wasn't too happy with that lol), but I'll definately work on a bigger port. Thanks again

[Triticum Agricolam]

No problem, glad I could help!