Neumann MM5U Omni SDC Tube Microphone #059 (Vintage)

The Neumann MM 5 (U) was the third in a series of Measurement Microphones (MM), each using an omnidirectional pattern, but with different tubes and capsule membranes. The MM2 was produced from 1949 to 1954, using a VF14 and a 10mm aluminum diaphragm. It had a flat frequency response from 30 Hz to 16 kHz +/- 1 dB. The successor was the MM 3 which was produced from 1954 to 1966 and had the same frequency response as the MM2; it also used a 10mm aluminum diaphragm, but an AC701k tube.

The MM 5 was produced from 1959 to 1970, using a 7.5mm nickel diaphragm and AC701k tube. This was the most sensitive of all Neumann tube microphones, registering from 20 Hz all the way to 40 kHz. In the lower half of the frequency range it was accurate within 1 dB, and in the upper half within 3 dB.

The MM series was used by Neumann to measure the performance of their production microphones, and were also used by many other microphone manufacturers. Because of their function, they were the most precise of the tube microphones made by Neumann from 1949 to 1970, with an extremely flat frequency response. They were only made in limited numbers, as they were not originally designed for general recording applications.