Hyper-Cardioid Dynamic Drum and Instrument Microphone. Designed, machined, assembled and tested by Audix in the USA, the D4 is a dynamic instrument microphone used for stage, studio and broadcast applications. The D4, which is characterized with a hypercardioid pickup pattern for isolation and feedback control, is equipped with a VLM™ (Very Low Mass) diaphragm for natural, accurate sound reproduction.