Big lows, punchy attack: the essence of a fat bass drum sound. In pursuit of capturing this rich dynamic, many acts of wizardry have been conjured up. If you feel a little scientific and have a couple of free tracks on your recording medium, here’s a simple two-mike trick to find the beef. First, place a large-diaphragm dynamic (e.g., a Shure Beta 52, Sennheiser e902, AKG D112, or similar microphone) just inside the port on the front head, aimed halfway between the beater and the edge to pick up a good balance of tone and attack. If there is no hole in the head, position the mike about 2" from and facing the head around halfway between the center and the edge. Placing the mike right at the center would pick up too much flap, and too far to the outside would pick up too many overtones, so find the right spot by listening.
Next, to augment the low end, take a large diaphragm condenser such as a Neumann TLM103, Shure KSM32, Audio-Technica 4050, AKG C3000B, or comparable transducer, and place it a short distance from the front of the bass drum. To figure out how far away to position the second mike, pull out the calculator and do a little math. Take the speed of sound (1,130 feet per second) and divide it by the frequency you want to reinforce — say, around 100Hz — to get the wavelength, and then divide that number by four (see diagram above).
A sonic waveform has the most power at the initial compression peak — the first quarter of the full cycle, so this equation gives you the perfect distance to put the mike to capture that big bottom oomph. In this example, the mike would go approximately three feet from the front head, around where the air blast from the bass drum dissipates. This position captures the low-end thump as well as the physical property of the air, allowing those qualities to be reproduced at the speaker during playback.
To achieve isolation from other sound sources and to enhance the effect of this two-mike technique, try constructing a tunnel between the source and the distant mike. Be creative: You could duct tape packing blankets in a rough arch between the bass drum and a sturdy chair set up behind the mike, or use sofa cushions to build a fort. The tunnel should have no parallel surfaces so as not to interfere with the sound adversely.