Bearing Edges: Sustain Vs. Attack
An entry-level drum made of mahogany can sound better by improving its bearing edge. Conversely, a pro-level drum made with the most exotic wood won’t perform optimally with a poor bearing edge. For the best results, you’ll want to line up all the right choices for the sound of your drum, including its drumheads, shells, and bearing edge.
Many drummers wonder what the ultimate bearing edge looks like. Unfortunately, that’s something no one can answer. The most you can do is to find out as much as you can about the types of edges used by drum companies, and how they interact with drumheads to produce various and often contrasting sounds. Only then can you make an educated choice about the edge most appropriate for the drum sound you desire.
A couple of companies have built the same drum models for years, but have changed the bearing edge three or four times in the process. I’ve repaired sets where the bearing edges were cut differently from one drum to the next. For example, a 12" tom might have a very rounded edge, while the 13" tom would have a very sharp 45° angle to the outside. On a rounded bearing edge, the contact point – where the head meets the bearing edge – sends the vibration generated by the head down through the center core of the shell. This causes the shell to vibrate from its center. A sharp bearing edge contact point transfers energy to the outer edge of the shell.
These two drums will never have similar sound characteristics, which could be a disaster if they were the 12" and 13" toms in the example above. On the other hand, it could work out fine if one edge was used on a bass drum and the other was a tom. It’s a matter of matching the right edge with the right drum.
A rounded edge focuses more on sustain and less on attack because the radius of the head follows the shape of the edge and has a lot of surface area contacting the shell. It’s a simple formula – the more surface area of the head contacting the shell, the greater the energy that is transferred to the shell. The combination of head and shell vibration yields good sustain. On the other hand, a sharper edge provides just the opposite sound – attack with shorter sustain. (Keep in mind that the type of head you use will also play a role in the sustain/attack relationship.)
A good all-purpose edge could be a combination of both types described here. One last point – whichever edge you choose should be inspected to insure its smoothness. If it isn’t absolutely smooth, the drum will be difficult to tune.