Select a microphone. A large-diaphragm condenser microphone generally is the best hoice for acoustic basses. A mic that adds bright, mid-high tones is used for lower-sounding instruments. Darker-sounding mics provide the best balance of sound for higher-pitched instruments.
Supplement the main bass sound with the pickup track, and avoid pickups. Many acoustic basses feature a small acoustic pickup. Bassist and sound engineers are tempted to rely on the pickup sound, the sound produced by these pickups lacks quality.
Position the microphone six inches from the strings and between the bridge and neck of the bass, which is where the strings are plucked. Have someone play the bass while you move around the venue If you want to test out additional microphone positions to find that "sweet spot."
Adjust the microphone position as necessary. Place the mic in the best position you audibly can identify. Cover one ear while you're listening to get a better sense of what the microphone picks up.
Test your setup with other instruments playing. The acoustic bass easily can be lost in the fog of the other instruments if you have a small venue. Isolate the bassist, if possible, when recording. Move the microphone a little closer to the bassist and mix in some of the pickup track if necessary.