The loud pop comes from the high forces deflecting the cantilever when the stylus is dropped into the groove. It is exacerbated by a number of factors. First, one must cue the down the arm slowly to minimize this force. The pop can become more of a problem if the cuing rate has changed (most cuing devices use viscous dampening and the tendency is for the drop rate to increase as the mechanism ages). If your arm does not allow for an adjustment to the drop rate, you will have to lower the rate yourself by slowly moving the lever each time you cue.
Sometimes the rubberize bar that holds the arm in place becomes less tacky which allows the arm to drift out of line when it cues down. If your arm provides antiskating, this causes the arm to drift outward toward the edge. If the arm cues too far out toward the edge of the record, the stylus will land on the high edge bead. The arm/stylus will then fall downward to the lowspot inside of the bead; this fall and abrupt stop is often the cause of a loud pop. Try cuing the stylus further into the record to avoid hitting the outer bead.
Slower cuing and cuing far enough into the record to avoid the outer bead is usually enough to minimize any sort of loud pop.
Sometimes the rubberize bar that holds the arm in place becomes less tacky which allows the arm to drift out of line when it cues down. If your arm provides antiskating, this causes the arm to drift outward toward the edge. If the arm cues too far out toward the edge of the record, the stylus will land on the high edge bead. The arm/stylus will then fall downward to the lowspot inside of the bead; this fall and abrupt stop is often the cause of a loud pop. Try cuing the stylus further into the record to avoid hitting the outer bead.
Slower cuing and cuing far enough into the record to avoid the outer bead is usually enough to minimize any sort of loud pop.