Sagging Voice Coils?

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.

It is true that some drivers need to be rotated 180 degrees due to becoming off centered. It has to do with the weight of the driver putting pressure on the surround over a long period of time. This is less likely to happen with smaller lighter drivers than with larger heavier drivers and the surround material has a lot to do with it. For example, a 12" poly cone woofer with an inverted butal surround would most likely benefit from periodic rotation.

If your drivers need to be rotated you should be able to see a difference in the width of the surround by comparing the top to the bottom.

Viridian, The surround on your Klipsch speakers is a continuation of the cone material. Also, the woofer in your speaker dictates the sensitivity of the speaker, so with 102db sensitivity the woofer cone is very light weight. It's not very likely to sag like some of the heavier materials, but if it does you know what to do.