This lesson involves a couple different rhythmic principles: dynamics and technique. It takes traditional dynamic techniques and turns them on their head, and opens up other possibilities. It's a simple lesson that will give you a skill that can be applied in many different drumming environments.
When you think of dynamics - playing quietly vs playing loudly - you often equate the louder notes with a harder, longer stick stroke. Pull-offs accomplish the louder notes with a shorter stick stroke. The difference is in the rebound, and how you manipulate that.
We often think of the rebound as something the stick does by itself; we sometimes work with it to create quicker stickings, but we don't often think of it as something we can control. Pull-offs teach us this control.
Before we start, I must say that this is a very difficult concept to teach on the internet. I really struggled with how to make this understandable through a printed page and some pictures. It's really something best passed on by a living instructor who can show you this technique and properly steer you to its perfection.
So, I'm going to try my best here, but please understand that it is a humble effort, at best.
The Four Different Sticking Strokes
There are four different sticking strokes in drumming, and each is defined by the position of the stick at the start and the end of each stroke.
1. Starting high, ending high
2. Start high, ending low:
3. Starting low, ending low:
4. Starting low, ending high:
How The Pull-Off Works
In order to do the pull-off, you must start low, and end high. But, it's a two-stroke thing: the first stroke is starting low, ending low, immediately followed by starting low, ending high.
It's this second stroke that's the "pull-off", because what you're doing is adding more force to the pulling up of the stick immediately after it strikes the surface. This is what makes the second stroke louder than the first, not the force that pushes the stick down.
Here's a little animated image that shows the stroke. Since it's looped, remember that it consists of two strokes: the first is starting low ending low, the second is starting low ending high.
The speed is slowed down here so you can see what's happening.
This technique is best practiced doing double strokes between the hands:
Refer to the animation. The first of each double is starting low, ending low, the second is starting low, ending high, but pulling the stick off the head to increase the volume once it strikes the head. (You are actually starting the pull-off slightly before the stick contacts the head - almost whipping it back). This makes the dynamics.
It's very difficult to do this smoothly and evenly when you are starting out. Be patient. The doubles should sound very smooth and consistent in their placement.
This second notation reverses the sticking.
This technique will greatly increase your speed when playing passages with varying dynamics. Orchestral and jazz drummers use this a lot, since they trypically play shorter strokes for greater control. They can now add a loud note in between quieter notes without sacraficing the the time and smoothness in bringing the stick up for the beginning of the stroke (in order to make a loud note by pushing the stick down harder).
It's magical to see someone do this who knows what he's doing. Take your time with this; I hope my explanation suffices - if it needs clarification, please let me know.
As always, let me know how you've done!