The KM 85 is a Cardioid pencil mic, built from around 1966 to 1990. The capsule has a fixed high-pass filter that rolls off at 4dB/octave below 500Hz.
In a sense, the KM85 is a KM84 with a low rolloff. The two mics’ polar patterns are identical, and very consistently Cardioid across the full audible spectrum (narrowing just slightly above 12kHz).
The KM 85 i incorporates a low-frequency roll-off which reaches about 12dB at 50Hz. This microphone is therefore much less sensitive to low-frequecny interference which may be encountered outdoors or in public address applications, while at close talking range, the characteristic low-frequency boost present in all pressure gradient transducers [aka proximity effect] is compensated.
A switch on the rear of the microphone enables a -10dB pad.
The KM 85 was wired at the factory for an output impedance of 200Ω. This could be changed to 50Ω by modifying the jumpers that configure the output transformer.
Like the other KM-8x microphones, the KM85 used Neumann’s innovative crossed-slit capsule backplace design, which contributes to the KM85’s excellent Cardioid pattern control.