Types of microphones
Omnidirectional (pressure) microphones have the great advantage of picking up sound evenly from all directions (although some “omnidirectional” microphones are slightly directional at the highest frequencies). Using an omnidirectional microphone is appropriate when you want to pick up the full sound of the instrument and you can maneuver it (using a gooseneck) a short distance away from the instrument.
There are many sound sources on the double bass. Due to its size there are several good spots to pick from. Using an omnidirectional microphone – like the 4006ES Omnidirectional Microphone
or the 4061 Miniature Omnidirectional Microphone
– allow you to pick any one place, close to or, by using a gooseneck, at a short distance from the instrument. Using an omnidirectional microphone ensures the sound will not lack low-frequency due to the proximity effect as when using directional microphones. Proximity effect is an increase in bass or low-frequency response when a sound source is close to a directional microphone.
Using a directional microphone like the 4099 Instrument Microphone
or the 4011ES Cardioid Microphone
has the advantage of being able to focus on the sound of the key instrument, isolating it from surrounding sound sources, such as other instruments onstage or the PA system. On the other hand, directional microphones suffer from the proximity effect and therefore require more adjustment to find the preferred position. Moving the microphone close to the instrument will increase the low-end response, which might be desirable.
Bear in mind that the double bass reacts as a huge reflective surface. The incoming sound from other sources (instruments, PA system) might reflect off it and enter the microphone from the front even if the microphone is pointing away from the source.
Tip: If the bass player prefers to stand close to the drummer, point the directional microphone away from the drum kit. This will minimize the bleed from the drum sound reflection off the bass.