How to do great cabinet, braces and stuffing

Dimensions

We start by founding our box volume and vent primary dimensions thanks to VituixCAD.

We will here try to not have dimensions that are the multiple of another in the same volume, VituixCAD give us a good tool for this (in Tools -> Auxiliary -> Box Volume) :

Braces

The IPN beam style brace have the best occupied volume efficiency ratio and work on all the frequency range, that will not be the case of a simple cross alone in the centre.

Corners and where two panels is glued together with an angle (90° for regular box) are already the most rigid part of the cabinet, it’s in the global center of a panel that we have to bring rigidity.

A cross in the middle without big strapping is useless, the cross alone work only at a precise frequency, not on a range of frequencies as a strapping (IPN style as showed)

Stuffing

Poly fill stuffing or pillow stuff is very low density stuff, it’s use for virtually increase the volume of a sealed box but it’s not very efficient about reflection absorption in the box.

It’s usualy used in selled box but generally not in vented box (or in very few quantity), as we are already at the Bessel ideal volume and this kind of stuff on the midle will also reduce the port efficient (so the bass extension), that we don’t want.

For the internal sides stuffing the best is to use this, 20mm(1 inch) waste fibre for car insulation:

It’s an high density stuffing material. On each side except front pannel and not on brace, doble the thickness on top and bottom when the speaker is tall.

I will naturally add a little bit of virtual volume that will compensate the volume that is taken by the braces upper, it’s all we want.

For the wubwoofer case:

Sealed we use a lot of Poly fill stuffing for virtual volume, for vented nothing or a very few of Poly Fill.

Usually the raisonances imply by the frequency range of a subwoofer is so low that the wavelength of the possible reflection is way more bigger than the larger side of the box so we will never have resonances in this case.