Bracing driver to box, deadening basket and wrapping magnet in felt

[tsnell]

Hi everybody,

I’m currently building my self a pair of Edgar Beers’ Eve II. There are a few steps in the procedure that I would like to better understand. I assume in an effort to best deaden the speaker, the driver magnet is mounted pressing against the internal box bracing (edge of brace covered in felt). Adhesive lead bitumen strips are then attached to the basket and the magnet wrapped in felt.

I am relatively new to DIY and am not disagreeing with these methods, but I am interested in understanding if and why they are effective. So basically I want to know some opinions and possibly hear some experiences of using any of these techniques, positive or negative. My main questions are:

1. Bracing magnet/basket to box structure – I imagine this is supposed to dampen resonances in the driver by not allowing it to vibrate. Is this assumption correct? Does this offer any performance advantage over simply connecting the driver to the baffle?
2. Adhering lead bitumen to driver basket – Does adding mass to the basket like this have any effect whatsoever? If improvements can be made so simply and cheaply, why is extra mass not added during manufacture? Obviously cost for cheaper models, but for high end drivers?
3. Wrapping magnet in felt – What is the purpose of this? Wouldn’t this negate some of the passive cooling effect from moving air flowing over the magnet? If so, isn’t the efficiency of the driver reduced with an increase in voice coil temperature?

Your knowledge and responses will be greatly appreciated.

tsnel

[Cal Weldon]

This is what get's done if planet10 Dave is looking after it. Perhaps he can explain the finer points. Alnico "hoop" wrapped in sheeps wool, Base of basket against magnet has duct seal.

[Cal Weldon]

Front side has the cone and surround treated and a phase plug added. Sorry but the shot with the flash was too bright.