A discussion on what makes for a good speaker box material.

[hobbyhands]

So is it density, reduced vibrations, what about that lightweight MDF stuff. I can't remember what it is called.

[timw]

Judicious application of stiffness (modulus of elasticity), and mass, in combination with damping (internal or extensional or constrained layer damping).
Damping may be measured as 1)loss factor, 2) damping factor, 3) damping coefficient, or 4) tan delta.

Material must have reasonable working properties. Must not crack or distort excessively with time. Must be able to facilitate creation of strong joints.

[Æ]

So is it density, reduced vibrations, what about that lightweight MDF stuff. I can't remember what it is called.

Practical application. Is it affordable? Is it readily available? Can it be sawn, cut to shape, sanded? Is it easy to work with? Does it look good? While I'm sure there are plenty of other materials better than MDF, they are usually too expensive or too difficult to work with. I like MDF simply because it is plentiful and if I screw up, no big deal, just cut another piece.

[andy19191]

So is it density, reduced vibrations, what about that lightweight MDF stuff. I can't remember what it is called.

The material follows from how the cabinet is designed to work. For example, if the lowest frequency cabinet resonances occur above the passband of the driver then stiffness is pretty much all that matters (e.g. subwoofer and woofer cabinets). Opt for a stiff material with a small amount of damping. Alternatively, if the lowest cabinet resonant frequencies lie in or below the passband of the driver/s then high damping becomes more important than stiffness. Few stiff materials have high damping and so this is often best achieved by adding extensional or constrained layer/s of damping material to a low damping structural material.