Small diaphragm microphones are useful on stringed instruments due to their low sensitivity and high dynamic range. Fluctuations in volume and performance dynamics, created by the various ways the bow is drawn against the cello's strings, are projected from the f-holes on either side of the bridge. Small diaphragm microphones are well-suited for capturing the nuance and warmth unique to a cello performance. The Royer Labs R-121 is a wonderful microphone for this task.
Large diaphragm microphones are more sensitive and have a lower dynamic range than small diaphragm microphones. They are well-suited in the studio to capture the sound of the room in which the performer is recording. The Rode NT1-A is a reliable and relatively cheap microphone with a large diaphragm. The NT1-A has a narrower frequency range than most small diaphragm microphones. When placed on the instrument, it should be near the neck of the cello, rather than at the bridge.
Dynamic microphones are popular in live and studio settings due to their ruggedness and reliable performance. The Shure SM57 dynamic microphone is a popular choice among audio engineers and home-recording enthusiasts alike thanks to its durability and low cost. The SM57 has a clean, bright sound and contoured frequency response, perfect for capturing the sound of a briskly drawn bow.
Microphone placement varies depending on the kind of performance the artist wants to convey and whether the audio engineer uses one microphone or a combination of two or more microphones. To capture a tight, crisp performance place a small diaphragm microphone one to two feet from the cello's bridge and f-holes. To capture a bigger, more dramatic performance, place a large diaphragm microphone farther away from the instrument.