The C391 B high-performance small-diaphragm condenser microphone has a cardioid polar pattern, a low self-noise and very good transient response for a bright and brilliant sound. It also features the ability to quickly interchange its capsule with one of the other capsules, making it an excellent mic for demanding broadcast applications. The C391 B provides a switchable bass roll-off / attenuator with three positions: flat, 75 Hz and 10 db attenuation.