Cabinet construction - compare wood types

[kipman725]

MDF - it's cheap and dense and well damped. The concerns about it pushing the resonance of the cabinet down are valid considering that there is more energy at lower frequencies but the cost advantage is very hard to ignore unless your spend on driver is >200GBP. However due to the much lower cost a more elaborate cabinet could be constructed that is much more damped than the same cost ply cabinet at the expense of size/weight (sand filled enclosures etc).

[zman01]

Just googled and downloaded some images of baltic birch ply cross sections.

If you look closely at the pics, you will notice:

1. Colors of the layers are different - some of the layers look light colored and hard, while others look slightly darker colored and a softer

2. Thickness of layers slighly uneven - and thickness of each individual layer is not uniform over the legth of the board(sometimes it looks slightly wavy)

I have never bothered to take such a close look at ply boards before, but is this normal?

[evanc]

the plywood layers alternate grain direction. when you cut across it you are seeing end grain on one layer and long grain on alternate layers. The core is glued together however it is and then the sheet is sanded to an even thickness. so yes the waves in the layers are normal. Baltic birch ply wood or apple ply are usually better then most in this respect.