Some questions about sealed design

[Trendkill 10+ year member]

In the image below are 3 different shapes for a sealed subwoofer box. The images are not to any scale. Assuming they are all the same volume, is there any reason they would sound different from each other? Are there any shapes I should completely avoid? Basically I'm trying to understand how much of a role shape plays in sealed design, if any.



Also, if a manufacturer recommends .8-1.5 cubic feet for a sealed enclosure, how do I determine where in that range I want to be? Does it matter much? I assume it would.

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[bk12321 10+ year member]

I have no idea if this is right, but I assume if the boxes are all exactly the same volume and are 100% sealed, that they should sound the same. Once you start throwing ports and other things into the mix it gets complicated. Don't quote me on that though haha.

And they give you that range because a .8 cubic foot box will sound different than a 1.5, but both could still be "optimal". If you have the t/s specs of your woofer you can plug it into a formula to figure out the qtc or total resonance of your speaker system, and if you have an idea of what values mean what, you can decide if you want a bigger or smaller box without ever having to actually hear the sub in the box.

A qtc of .707 has the flattest resposnse, most "accurate"/punchy bass, and lowest possible f3 value for that driver. Once you start varying from that number, up or down, it has an effect on the sound.