The AKG D12 is a cardioid dynamic microphone with a built-in "bass chamber" in the head basket designed to enhance low frequencies from 50 - 200Hz, and an internal shockmount which isolates the dynamic coil / capsule from the rest of the microphone and the floor. With these features, plus an ability to take very high levels of SPL before distortion, the D12 was quickly recognized as a premiere microphone for kick drum and other loud bass instruments. This microphone was widely used in Europe in the 1950s and 1960s, most famously at Abbey Road with The Beatles.