The IRPA MK15 is a distinctly rare small-diaphragm Soviet tube condenser from the mid-70's. It was developed and manufactured in small quantities, as few as a few dozen were ever made. It shares a lot of the same design features as the other mics in the MK family of IRPA microphones, such as the MK12 and MK13. Like it’s siblings, it uses the soviet 6S31B subminiature tube which is also used in the LOMO 19a19. It also shares a capsule (and PSU) with the MK12, which is a surprisingly accurate copy of the Neumann KK84 capsule, and shares the same sonic characteristics.
What makes this microphone particularly unique is its outrageous shape and the plastic disc that mounts to the top of the capsule. After doing some deep digging on Soviet message boards, I learned that the disc and the shape of the microphone are designed to create a “hemispherical polar pattern”, which in theory would suggest that it only picks up sound from the space above the disc, and rejects all sound below the disc, effectively behaving like a suspended boundary mic, likely intended for speeches or conferences, and surely to be used as room mics in an upcoming session.
