Phoenix Gold Phorum

I am planning on building a new enclosure for a new sub for my truck. I am going from the 3 15's to a single 18" Re Audio SXX. The compact enclosure reccomendations are 5.5 Cu. tuned @ 35hz. I know with port displacement and sub displacement My box will be close to 7cu. Here comes the tech. question. I want my sub to be behind the passenger side seat and I want the Port to be between the seats (in the middle of the enclosure) facing forward (like the sub). Will the placment of the port have an effect on the sub? tuning or sound wise?

To a point yes, but it also depends on the type of vehicle it's going in. It's preferable to have the port and sub on the same plane.
IMHO I prefer the port to be dash level and above for you explained setup.

Size (opening area) of the port will be crucial as well.

Well here are some specs:
Box Dimensions Outter:
Width=58.5"
Heighth=25"
Top Depth=7.5"
Bottom Depth=13.56"

Port dimensions Internal:
Width=15"
Heighth=6"
Total Length=20"

Surface area of port would be 90sq. inches.
Tuned for 35hz. I have a blueprint scetched out, will try to get it scanned and posted.

Are you sure that 5.5cuft doesn't include port displacement? That is a mighty large box!

yes it is...port displacement is 1.29Cu. and sub displacement is .22 which totals 1.51cu. minus the 7cu. = 5.4cu. It is huge!!!I basically have the same box in the truck now with 3 15's in it.

anyone else have an opinion or info on the question.

I agree that you should try to have the port at the front of the box. The length and shape of the port decides the tuning frequency, but the phase depends on where you aim it. If it's pointed forwards with the sub, it should be as in-phase as possible.

Essentially a port acts like a speaker... it just moves air. But we don't put speakers all over the different faces of the sub box! Sometimes though, moving a port is a matter of necessity. In some cases it can be louder and sound better, e.g. firing it through your parcel shelf instead of your seats.

stipud wrote:I agree that you should try to have the port at the front of the box. The length and shape of the port decides the tuning frequency, but the phase depends on where you aim it. If it's pointed forwards with the sub, it should be as in-phase as possible.

Essentially a port acts like a speaker... it just moves air. But we don't put speakers all over the different faces of the sub box! Sometimes though, moving a port is a matter of necessity. In some cases it can be louder and sound better, e.g. firing it through your parcel shelf instead of your seats.

That what I though as well but I wanted to see if someone else would have a technical reason agaisnt the placement of the port. Thanks for all your help.