walpurgis
02-08-2012, 22:27
If you have a bass driver that has a rubbing or binding coil, I have a dodge that I've used a number of times.
Find out where the coil is rubbing by applying gentle pressure to the side of the cone inside the chassis, not on the front, all the way round and moving it back and forth slightly. The area most prone to binding will become evident. Mark the chassis at that point with a felt tip pen for reference. Using a hair dryer on hot setting blow into the speaker chassis behind the cone and heat the rear spider all round, that's (normally) the corrugated fabric ring and apply mild pressure to the cone just in front of the spider on the opposite side to that you previously marked, then set the dryer on cold and keep blowing onto the spider. You may need more than one attempt, but it generally works, unless the coil or former is damaged or there is rust or other contamination in the magnetic gap.
The basic principal is that the heat of the dryer relaxes the setting of the spider and allows it to be reset, i.e. fixed in a new alignment.
Find out where the coil is rubbing by applying gentle pressure to the side of the cone inside the chassis, not on the front, all the way round and moving it back and forth slightly. The area most prone to binding will become evident. Mark the chassis at that point with a felt tip pen for reference. Using a hair dryer on hot setting blow into the speaker chassis behind the cone and heat the rear spider all round, that's (normally) the corrugated fabric ring and apply mild pressure to the cone just in front of the spider on the opposite side to that you previously marked, then set the dryer on cold and keep blowing onto the spider. You may need more than one attempt, but it generally works, unless the coil or former is damaged or there is rust or other contamination in the magnetic gap.
The basic principal is that the heat of the dryer relaxes the setting of the spider and allows it to be reset, i.e. fixed in a new alignment.