The Sennheiser MD 421 is a large‑diaphragm dynamic cardioid microphone that became a broadcast and studio standard after its introduction in 1960. This classic mic is valued for its clear sound, strong directionality, and ability to handle high sound‑pressure levels without distortion. It features a smooth frequency response from 30 Hz to 17 kHz and includes a five‑position bass roll‑off ring that lets engineers tailor the low‑end for speech, close‑miking, or loud instruments. Its sealed housing design maintains the cardioid pattern regardless of how it’s held, and a hum‑compensating coil helps reject electrical interference. With an output sensitivity of roughly 2 mV/Pa, a nominal impedance of 250 ohms, and a standard 3‑pin XLR connector, the MD 421 is a go‑to for toms, kick drums, electric guitar cabinets, horns, and broadcast vocals.