Curious on different port lengths in same box

[shizzzon 461]

Has anyone tried this when they were bored or may just know what happens if you take a ported box and install 2 ports in the box, one tuned to let's say 30 hz and the other at 45 hz.

I'm just curious as to what happens.

Does the box react as if there is a major air leak?

Do the port's tuning medium come into play and output a tuned frequency of 38hz for this example?

[aznboi3644 2]

There is an article I read about this a while back...it acts as if its tuned to a single frequency still IIRC. Not sure though

[Viperoni 0]

Do the port's tuning medium come into play and output a tuned frequency of 38hz for this example?

From what I understand, this is more or less what happens.

[shizzzon 461]

well just to keep curiosity goin, let's say that you need a port longer than what will fit without bending. So, you instead fabricate the remaining required length for a 2nd port which makes the medium of both ports equal your desired tuning.

Now, i'm sure there has to be something bad about this compared to just making the port correct the way you are suppose to but still interesting.

[danssoslow 0]

well just to keep curiosity goin, let's say that you need a port longer than what will fit without bending. So, you instead fabricate the remaining required length for a 2nd port which makes the medium of both ports equal your desired tuning.

Now, i'm sure there has to be something bad about this compared to just making the port correct the way you are suppose to but still interesting.

If I'm reading you right, than what you have stated is an impossibility.

-Let's assume that the two port thing is correct in that two different sizes will create a tuning that is somewhere between the two.

-You say you have a target tuning frequency, a frequency in which one port would be too long without bending the port.

Now, knowing that a single straight port will be too long, the two port/split the difference technique wouldn't work because in order to reach your desired tuning "average", one of the two ports would have to be longer than the original single port that is too long itself to begin with. Now I'm screwed up...

[shizzzon 461]

you are right. I was gonna post an example frequency but decided not too because of that dilemma, lol.

Got an idea off top of my head, use a very small port opening for the longer port, let's say 2" diameter.

The rest can be 4" or more.

[danssoslow 0]

you are right. I was gonna post an example frequency but decided not too because of that dilemma, lol.

Got an idea off top of my head, use a very small port opening for the longer port, let's say 2" diameter.

The rest can be 4" or more.

This is just a guess here, BTW; but I figure there would be a tonal difference between the two ports. Like a tuba and a trumpet playing the same note.

[shizzzon 461]

check this out... if this theory works.

According to box graphing-

Take 1 sub in a 1.0 cu ft enclosure after all displacements.

give it 1,500w of power tuned to 32hz.

Recommended port area for flanged port is 12sq in.

non bended port and port displacement -

4" port (12.57sqin) 29.5" long

displacement - 0.209 cu ft

Same tuning with this wack theory, hehe -

26hz tune for 2" port -

2" port (3.16sqin) 10.75" long

38hz tune for 4" port -

4" port (12.57sqin) 20.0" long

Port displacement for both ports combined - 0.158 cu ft!

Total port area - 15.73 sq in!

Result-

If this theory works, you gain more port area AND lower port displacement.

Pretty interesting if it's true... and audibly satisfying.

Old school port, slot port -

(just for reference)

slot required 16sqin per cube vs aero recommendation at 12sqin per cube.

4x4 port sharing 2 of 4 walls using 0.75" mdf with length 39" long subtracting 2" for active length running along wall.

Port displacement of slot - 0.473 cu ft!

Now tell me if that isn't a major difference!

[aznboi3644 2]

check this out... if this theory works.

According to box graphing-

Take 1 sub in a 1.0 cu ft enclosure after all displacements.

give it 1,500w of power tuned to 32hz.

Recommended port area for flanged port is 12sq in.

non bended port and port displacement -

4" port (12.57sqin) 29.5" long

displacement - 0.209 cu ft

Same tuning with this wack theory, hehe -

26hz tune for 2" port -

2" port (3.16sqin) 10.75" long

38hz tune for 4" port -

4" port (12.57sqin) 20.0" long

Port displacement for both ports combined - 0.158 cu ft!

Total port area - 15.73 sq in!

Result-

If this theory works, you gain more port area AND lower port displacement.

Pretty interesting if it's true... and audibly satisfying.

Old school port, slot port -

(just for reference)

slot required 16sqin per cube vs aero recommendation at 12sqin per cube.

4x4 port sharing 2 of 4 walls using 0.75" mdf with length 39" long subtracting 2" for active length running along wall.

Port displacement of slot - 0.473 cu ft!

Now tell me if that isn't a major difference!

Both ports will also have completely different velocity profiles so the tuning will be wierd