Sagging Voice Coils?

Heard the same tall tale but have never seen it nor have it ever been an issue, so I would not worry about it.

Happy Listening

Peter

There were and maybe still are speakers that have a coated surround that is usually made out of cloth. This was done a lot in the '60s to '70s and maybe before or after that time period. If you see some old woofers from around then, that has a liquid looking coating on the surround, it usually sags to the bottom. Those are probably what they are referring to. The owners of those usually do rotate them them a half a turn to put the heavy part at the top, and eventually the liquid will sag down again. It's sort of a super thick honey looking compound. This is done on some accordion surround edges of all paper/wood pulp cones to help keep them flexible and to help prevent cracking or tearing from all the movement they do.

Yes, the talk on the net is for real. They used that dope on midranges and maybe even tweeters. Some said it also was for dampening. It always seems to stay shiny and new looking.

The talk about the voice coil rubbing happens too. I don't recall the brands, but they must of had heavy woofers. These were all vintage that I know of, but not all brands. The spider keeps the voice coil centered, but the weight of the cones on the surround, and spider will let the gap get tighter. I've felt older speaker cone movement that was tight do to this. They would scape on the one side only, that was apparently do to sag, if you carefully moved them. I rotated them before selling or trading them.

With newer materials, there doesn't seem to be any problem anymore, but who knows when they get older.

Some of the weighted drivers from VMPS needed to be rotated occasionally. It's the cone that sags not the voice coil. I don't know if they are still around.