The Neumann U87 presents a wide range of features and versatility that make it to one of the most desirable mics available. The distinctive design is easily recognized and the microphone is well known for its warm and balanced character. Although primarily considered as a vocal microphone, the Neumann U87 can capture an entire orchestra or be used as a spot mic on single instruments. The applications are truly endless.
The U87 is equipped with a large dual-diaphragm capsule with three directional patterns: omnidirectional, cardioid and figure-8. These are selectable with a switch below the headgrille. A 10 dB attenuation switch is located on the rear. It enables the microphone to handle sound pressure levels up to 127 dB without distortion. Furthermore, the low frequency response can be reduced to compensate for proximity effect.
The U87 Ai is addressed from the front, marked with the Neumann logo. The frequency response of the cardioid and figure-8 directional characteristics are very flat for frontal sound incidence, even in the upper frequency range. The microphone can be used very close to a sound source without the sound becoming unnaturally harsh. By means of a high-pass filter interferences through subsonic and low frequencies are reduced remarkably.
The dual-diaphragm capsule is elastically mounted and protected by a large headgrille. A switch below the headgrille selects the three directional patterns: omnidirectional, cardioid and figure-8. A window above this switch shows the symbol of the selected characteristic.
The letter A in the name indicates a more recent generation, as compared to the U87 i microphones that were built from 1967 to 1986. Modifications apply to the electronic components of the microphone only; the capsule remained unchanged.
The present-day circuitry increases the operational headroom of the U87 Ai by supplying the bias voltages for the capsule through a reduced resistance. The result is a higher sensitivity of 10 dB for identical sound pressure levels, and an improved S/N ratio of 3 dB.
FILTER AND ATTENUATION
A switch located at the rear attenuates the sensitivity by 10 dB. When this switch is activated, the microphone accepts sound pressure levels up to 127 dB (equivalent to a sound pressure of 45 Pa) without distortion.
An additional switch at the rear allows to change the microphone's cutoff frequency. This reduces low frequency interference directly at the input of the microphone amplifier.
This setting also compensates for the unavoidable bass boost that occurs with all pressure gradient transducers when they are used at close distance (proximity effect).
The cardioid characteristic maintains a smooth frequency response at a distance of 30 to 40 cm, the figure-8 characteristic even at a distance of 15 to 20 cm.