The AKG C 451 EB is a modular condenser microphone system with phantom-powered solid state electronics and, most commonly, a CK1 cardioid capsule. Other capsules with different polar patterns and acoustical properties, as well as barrel pads could quickly screw onto the preamp body for different applications. A switchable high-pass filter on the body of the microphone toggles between flat response, 75Hz corner, and 150Hz corner.

At the time of release in the 1970s, the C 451 EB offered extremely low noise floor and high SPL handing.