Audyssey ACM1HB Calibration Setup Microphone – Genuine OEM (from Onkyo TX-NR616). The original pointed Audyssey ACM1HB setup microphone used to run room calibration on Audyssey-equipped AV receivers. The receiver uses it to measure your room's acoustics and automatically set speaker levels, distances, crossovers, and EQ for the best sound. This mic shipped with the Onkyo TX-NR616 (Audyssey 2EQ), and as the standard ACM1HB Audyssey mic it's also compatible with Audyssey-equipped receivers from Onkyo, Integra, Denon, and Marantz that use this mic. Important: this is the pointed Audyssey microphone—NOT the round AccuEQ puck used on later Onkyo models. Omnidirectional capsule with a long cable and a standard 3.5mm plug; the base has a tripod thread so you can position it at ear height. A genuine OEM replacement if yours was lost or missing from a used receiver.