The Sony C800G is a large diaphragm tube condenser microphone with polar patterns switchable between omnidirectional and cardioid. It is a departure from earlier Sony microphones in that it uses a K67-type dual diaphragm capsule. One 6AU6 tube resides inside the microphone's amplifier, and two are in the power supply acting as rectifiers.

The major update from the original C800 (non-"G") is that the C800G makes use of a very large heat sink/cooling system which measurably lowers the noise and distortion specifications.