Break-in of a woofer is essentially just stretching out the suspension. The spiders will be coated with a phenolic resin that is very stiff at first. It needs to be stretched back and forth a few times to loosen it up to it's normal operating compliance. The same goes for a surround, whether foam or rubber. Once it comes out of the mold it needs to be stretched a few times to it's extents to loosen up a little.
Playing at low volumes really won't do anything. You need to stretch it to it's limits or close to it in order to break-in the phenolic and the surround. We break-in every driver we build prior to measuring parameters. We run a simple 10Hz sine wave in the free air test enclosure to get the drivers moving nearly to excursion. We do this for about 30 sec and that is all it takes to be 95% broken in. You can actually physically push the cone forward and backward to it's limits one or two times to accomplish the same thing.
Depending on how much phenolic is used to get the given stiffness for the spider, it will eventually break down more over long periods of time. If there is a lot of phenolic the suspension can greatly soften over the years. The continual motion over time will wear down the phenolic, as well as environmental issues. We're working with a supplier on some new chemistry's instead of the standard phenolic, to treat cloth for spiders. It appears we will have something that doesn't break down over time. It will have the initial break-in period, but then should remain the same 1, 5, 10, 20 yrs down the road.
John
