Overhead microphones are positioned approximately 36 inches above the rack toms, pointing down. This technique typically requires only two microphones, placed equidistantly from the snare. The purpose of overhead microphones is to capture the ambient sound of the kit, rather than individual drums. It is a convenient solution if you have only two microphones, or if you want to produce a less intense drum sound. One drawback of this technique is that you have less control over the levels of the individual drums.
For a more precise approximation of the drum kit sound, point a microphone at every drum and cymbal on a kit. This enables the engineer to adjust the volume level of each drum kit component individually, to exercise greater control of the sound. Live drum microphones, such as the Shure SM57, are significantly less sensitive than studio microphones. This is because one of the main objectives of amplifying a drum kit is to get as much volume with as little feedback as possible. Live microphones, due to their lower sensitivity, do not capture as much “spillage” as sensitive studio microphones.
This technique is best suited to a large venue, such as a large club, theater or stadium. By capturing both the ambient and the individual sounds of the drums, you can blend the two feeds together to create a more detailed audio image.
Smaller venues typically provide less powerful audio equipment. This restricts the amount of volume you can generate from the house system. In some cases, the house system may be marginally louder than an acoustic drum kit, therefore there is little point in amplifying the sound of all drums. By amplifying the kick drum only, you can add a boost to the bottom-end, so the audience can feel the pulse of the songs without being blasted by a fully amplified kit.
This technique enables you to isolate the sound of the kick drum. By placing the mic inside the kick drum, you capture an omni-directional sound. Because the microphone is enclosed, it picks up less spillage from other drums and instrument amplifiers, enabling you to better control the sound of the kick drum.