Duck Tape Speaker Repair:
I found these EPI-100 speakers at the dump. My Cizek Model Ones needed re-foaming so I replaced them with the EPIs while I worked on the Cizeks. Everything seemed fine with the EPIs until I cranked the volume up one day and the bass suddenly disappeared!
I took the grills off and discovered that not only had the foam ruptured but the spiders had let go! However, the voice coils and wires were fine even though the coils were no longer in the magnet! With a little online research I determined that this was pretty typical of the woofers that EPI used during this period and since the spiders were gone they were not worth re-foaming.
The Cizeks on the other hand still needed to be re-foamed and were worth the effort. So, what the hell, I duct taped the cones of the EPIs back into their frames! I used a flexible cloth tape from Shurtape to replace the foam surrounds. I think it is technically "gaffers tape" rather then true duct tape.
I held the cone in and roughly centered while I placed strips of tape around the edge. I started with one strip about 10:00 o'clock and another at 4:00. Then 2:00 and 8:00. Once the cone seemed stable and centered I filled in the rest of the circle with more tape trying to keep loose and flexible. If you look at the picture at the right below you can see how there is a "tape valley" between the edge of the speaker cone and the frame.
I played music while applying the tape so I could correct any voice coil/magnet
interference on the fly. It bloody worked! The speakers sound amazingly good with only a
little cone bottoming at very high listening volumes.