The most common placement for miking a cello is to place a wide-diaphragm condenser mic directed at the F-holes of the instrument. A distance of anywhere from 6″ to 3′ is appropriate, depending on the desired amount of room sound and bass response. As with the violin, a cardioid pickup pattern is usually a good choice, or omni and bi-directional patterns can be used when recording in an acoustically pleasing room.

See also How To Mic A Violin or Viola