Sagging Voice Coils?

Step Six is speaking of the spider sagging toward the magnet(read it again). Something that I ran into frequently, with older woofers, when in the reconing business. Just the opposite of what one would get, in a downward firing woofer. That would occur quite often, in the humid Florida climate. The moisture would weaken the sizing(stiffening agent) in the spider, and allow the pleats to distort/warp. On occasion; I'd run into a woofer, with a pleated cloth surround, that had the same problem, and a rubbing voice coil. It's not hard to see how the same thing might happen, do to age.

Rodman, if your referring to me, the woofer cone is pulling on the spider causing the distortion in its (spider) shape. If there was no cone weight on it, I doubt the spider would sag in its lifetime. The midrange and tweeter with their light cones gives anyone an idea, the spider itself is not the problem. That's self explanatory with the woofers weight being the major cause of this problem. FWIW, there's still a problem with sagging from the weight of the cone. Some have it more than others. Larger gaps allow for more error. Also lighter cones, stiffer surrounds, and stiffer spiders along with other design factors come into play for the failure rate. Again, the problem still exists for some.

Michael, I'm embarrassed to admit I wasn't present at the bris.

I'm just talking from my personal experience, as a speaker reconer. The article YOU cited, was referring to the spider sagging towards the magnet structure(not the frame), and states exactly that. Like I said, I don't doubt that could occur, do to age, but- my encounters have been a result of damage caused by Florida's high humidity.

The article should be more specific. They should state something in the order that the sag could cause it to be off center. I think their main concern is to get the person doing it with no knowledge, good even clearance around the coil. If they're referring to upward firing woofers, I can't think of any companies that do this. I wasn't sure if you knew that I understand how the speakers are designed. I think we both know what is going on.