Just a few comments on the whole tinsel lead issue. It's one of many challenges I had to deal with and try to find a solution to. First is the obvious issue of standard tinsel leads that exit through the bottom of the cone, then somewhat "loop" and go to the terminal. There is a very hard balance between them being long enough to not pull, but yet not too long to slap on the cone. You can put the foam blocks under the cone, but you are then adding an amount of pressure pushing upwards on the cone that can cause the coil to rock sideways. If you had a DVC driver with leads on both sides that were exactly the right length, then it wouldn't be an issue, but that is very hard to do. If done right though, and with the correct twist to the leads as they are going to the terminals you can usually get pretty good reliability. At extreme excursions though, you do put a good amount of stress on the solder joint to the terminal. Getting it too hot makes the lead stiffer further away from the terminal. Instead of flexing it will be rigid and actually bend. With any piece of metal if you bend back and forth enough times it will break. This is still in most cases a reliable method and should be reliable most of the time. The higher the excursion the more difficult it is to do.
The second option is what TC Sounds had done with full woven in lead wires. The problem with this is that these leads are inside the cloth before it is formed into a spider. The spiders are formed with pressure and heat to get the shape. This pressure and heat not only stretches the tinsel leads, but it also makes them brittle. Try taking one of the tinsel leads and bending it. It's usually very soft. Now hold the soldering iron on it and it from then on becomes very stiff. This means it can easily crack or fray when it flexes to extremes and has a lot of stress on it. As it frays, it will be held together though by the cloth in the spider. It can spark and actually melt the cloth and in extreme circumstances start a fire. I know of one large manufacturer who had this issue in the past. There are also no vendors in the US who make these spiders, and China vendors really vary in consistency with spiders. It gets rid of the issue of lead slap, but has it's own set of issues.
The third option is to sew the lead wires to the tops of the spider. This keeps the leads much more flexible as there is no heat applied to them. You can put the right amount of slack in the tinsel leads to avoid any non-linear pulling throughout the travel. You also avoid any chance of contacting with the cone. The difficulty with this is finding them. Again, nobody in the US had done these. The same issues are there with China. Taiwan does it well, but they require huge quantities. We did finally convince one vendor in the US to do these, but then due to some other issues went on and bought the equipment to do them ourselves. The main drawback to this was the cost of labor to do them this way.
John
