Rockford P3D4 single sub with Alpine MRV-M500 questions on box build

[Scalian]

I have the following Rockford P3D4 single sub with Alpine MRV-M500. I want to build a sealed box, for my 2009 Altima sedan.

Rockford suggests a 1cu. ft box.

Would this be 1 cu. Ft after sub displacement. Say sub displaces .2 would the box need to be built to 1.2cu ft?

There are a lot of external dimension that would come out to be a said Cu Ft volume. Does the shape of the box make a difference. Would a square box sound different that a rectangular box of the same volume?

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[What was that? 10+ year member]

You are correct. You must consider bracing and sub displacement and add it to the overall box volume. Shape does make a difference. Square is not the best. Sealed boxes are much more forgiving if you miscalculate a bit, so don't worry. With sealed bigger is usually more boomy and smaller is more accurate.

 

[Scalian]

Is square isnt the best how do you go about figuring out what dimensions are the best? Is there some general rule or calculator to use?

 

[winkychevelle 10+ year member]

Honestly after playing with rockford subs for a while I would keep the box around 1.35cubes or port it.

As far as the shape goes there is a rule but its not too important in typical installs. One easy way to negate the rule is simply to slant or angle the wall behind the subs motor. This keep the sound wave coing off the back of the sub moving away from the sub. In a square design that sound wave reflects directly back at the sub and can cause distortion.

A bit of fiberglass insulation or poly fill sheeting can help mitigate this as well if you cannot work it out in the box design.

Typically it is better to have a rectangle box than a square one.

 

[Scalian]

So making the front of the box straight and angle the back to match seat would be best?