A true classic, over half a million MD421s have been sold since its release in 1960. Although there have been a handful of revisions over the decades the design has been mostly unchanged. As with other Sennheiser microphone there is a high-pass filter switch with “M” (for Music) being full range and “S” (for Speech) filtering all the way up to 500Hz. The MD421 is commonly used as a spot mic on toms and bass drum, but is reliable on amplifiers, horns, and Leslie cabinets.