Changing the tuning by adding external port length.

[Maticus]

Basically what the topic says. I'd like to change my tuning on my box from it's current state of 45 Hz down to about 32 by adding a screw on external port piece.

I need to know how one goes about tuning with part of the port being outside and part inside, like thor's port.

Could anyone link me to some other threads, or tell me how to figure it up?

[anubis]

you have an aero or slot? cuz he has the aero now?

[Maticus]

you have an aero or slot? cuz he has the aero now?

I have a simple slot, I was just using him for an example because a large portion of his port is outside of his box.

[zfrerichs]

you can add external ports to lower tuning

[tacomabanga1986]

i changed my tuning by just inverting my subs, wit mag in box it was loud as hell with around 40 or so hertz music but inverted its the same loudness or louder with the lower 32-36range, i guess without motor displacement its a diff box

anywho, dont changeing the port area affect tuening too or how well the box displaces air? cause mine is loud but doesnt push out air like i thought it would

anyways hope u get it figured out

[Maticus]

i changed my tuning by just inverting my subs, wit mag in box it was loud as hell with around 40 or so hertz music but inverted its the same loudness or louder with the lower 32-36range, i guess without motor displacement its a diff box

anywho, dont changeing the port area affect tuening too or how well the box displaces air? cause mine is loud but doesnt push out air like i thought it would

anyways hope u get it figured out

I'm in a tough enough spot as it is with seating space, I have two 10" L7s behind the seats in a single cab truck, no way could I invert them, and the port I'm running with now is kind on the low side of the "rule of thumb of cubic inches to cubic feet" it's right at 13, so adding a bit of port shouldn't hurt me at all there.

[zfrerichs]

yes, increasing port area will in return cause the need for the port to be longer to achieve a lower frequency.

inverting woofers will increase box volume and lowering the tuning a tad because the ratio between internal airspace and port area has decreased. So lets just put it like this, if you are to invert your woofers it will increase box volume, decrease inches of port per cubic foot, and lower tuning a tad.

[Maticus]

yes, increasing port area will in return cause the need for the port to be longer to achieve a lower frequency.

inverting woofers will increase box volume and lowering the tuning a tad because the ratio between internal airspace and port area has decreased. So lets just put it like this, if you are to invert your woofers it will increase box volume, decrease inches of port per cubic foot, and lower tuning a tad.

All I'm really wondering is how can I figure the tuning with part of the port taking up airspace, and the outer portions not?

[anubis]

just extend the common walls but do well do brace the external portion of the port and youll keep your volume while lowering tuning you measured for

[zfrerichs]

its the same calculations as before, but now you have extra room to play with on the port instead of making the port longer and shrinking the box.