Hello there guys and gals.

Built a box for spl , with the drivers facing upwards.

Just was wondering which way shall I do the holes for the 4 inch ports.

The ports will be inside the box and not external.

I just want to get some opinions before I go and make holes and will not be happy with it.

Any views would be appreciated. and , my car is a hatch back so the seats fold down as welL.


Thanks champs!

what year astra?
you would never know for sure untill you did some testing but up would most likely be the way to go in an astra. due to limited box room.

It is 1989 model.

The box has taken most of the space in the boot area only little space is on the sides just past the wheel well has about 6 inch of space on each sides so I was thinking that was the ideal spot according to the speaker box manual, the ports need space to breath????

Thats rebadged Pulsar.. Port up sub up seems to work in those.

Thanks for the advice Blackice.

I may manage to squeeze the ports next to the subs.

I hope I don't damage the sub if I mount the port close to the speaker..any thoughts?

The chances of it causing damage is about as good as winning Lotto.

Thanks for the advice again Blackice.

Just a question regarding the port on the speakers manual is that the port cannot be close to the side walls by the diameter of the port, in this case, 4 inch away from any walls.

Any reason why they stated this in their box building manual?

It doesn't really matter too much if the end/mouth of the port is near the speaker. But if it is too close to one of the walls, it will alter the tuning of the port because airflow around the port will be reduced (either effectively reducing the diameter of the port, or adding extra air mass to the port).

if ya wanna make to 4'' ports and ya ndont have enough room have ya considered putting a slot port in the box instead just an idea.

The distancing is because fouling of the end of the port alters the tune. Typically the wall to the sides makes little to no difference. The wall behind the port CAN cause massive tuning issues. Keep the port atleast its diameter away from the wall behind it.