E30 Zone

Right getting a bit of headache so looking here incase any one has any experience in making sub boxes.

I have been using a calculator to make the right size box so has the correct volume and frequency for the sub I have. However, when putting in the dimensions, it only allows the front of the box to be sloped.

Now my problem is, I want to slope the rear of the box. This way I can have the base of the box longer to utilise the small amount of space under the hood compartment in the boot, and then have it slope up and have the top section still come out say 10" from the hood compatment outwards. This would mean I can get the right volume.

The calculator I have been using though will only allow me work out the front of the box being sloped, so it doesnt take in to account the port on the boxbeing affected by the rear sloping.

Will I be able to get around this by making the port wall along the back longer to keep the frequency as it should be?

I hope that makes sense, if it doesnt then let me know and il try and clarify what I mean.

ALll help is greatly appreciated!

http://www.crutchfield.com/learn/learni ... tml?page=2


I've found this link very helpful when I did mine...

Thing is I need to work out how swapping the slope from front to back will affect the porting of the box which that guide doesnt say anything on.

I've been told that by increasing or decreasing the port walls, it will only change the frequency in small amounts at a time. Now swapping the slope over means the front ported part will increase in size while the back will decrease, so the side wall of the port will stay the same roughly. So is it just a case of increasing the rear port wall that runs paralell along the back wall to make the port the size it should be and kee the frequency where it should be?

Anyone know? Want to start building it this week so can get fitting it.

Right well picking up the final parts for my install tomorrow so need to start desiging this sub box so I can get it all in the car. Any one have a way of calculating it best? Basically I need it sloped at the rear to utilise as much of the space under the hood compartment as possible, and then still have the cubic space of 2.2cubic feet and a frequency uned to 33hz.