Compositionally speaking, the bass drop in a drum 'n' bass or dubstep track is the point at which the full bassline enters the mix. More importantly, the bass drop is the point at which the crowd goes wild. The bass drop is the most memorable and recognizable section of your track; to ensure that it has the fullest possible impact on the dance floor, use a few techniques that can help you produce a good bass drop.
Count the number of bars in the song before the bass drop. The bass should drop immediately after a bar that is an even multiple of eight. For example, the bass drop on a short track might fall on the ninth bar, while a longer track's bass drop might enter on the 33rd bar. Following this convention makes it much easier for DJs to mix your track into a set, and fulfills the expectations of the listener's ear.
Focus on the bassline itself during the drop; you can bring in other melodies and vocals later in the track. Use the main bassline riff of your track for the drop. The bass drop is the most iconic part of a track, and, especially in a dubstep track, is often the track's "hook." Layer different bass synthesizers to create a full, rich sound for the bass drop.
Cut out all of the other parts of the song just before the bass drops. A small section of silence just before the bass enters the mix makes the bass drop more powerful. For even more impact, layer a spoken-word vocal sample into the mix just before the bass drops.
Increase the volume of the drums slightly after the bass drops. The volume increase should be almost unnoticeable. When you play your track on a club sound system, this subtle change in the volume dynamics will add a subconscious impact to the bass drop. Add extra percussion sounds to the drum pattern during and after the bass drop.
Use a sound that rises in pitch to lead into the bass drop. A rising sound indicates to the listener that a new section of the track is beginning, and builds anticipation for the bass drop. To build even more anticipation, make the lead-in sound rise, then fall, and then rise again to an even higher pitch before breaking into the bass drop.