The Neumann U 87 Ai is arguably the most famous and widely used microphone manufactured by Neumann. It boasts a large dual-diaphragm capsule, allowing for three polar patterns: omnidirectional, cardioid, and figure-8. Selecting between these patterns is easily done with a switch conveniently located under the protective grille.

On the back of the microphone, there is a 10 dB attenuator switch which permits distortion-free operation at sound pressure levels up to 127 dB. Furthermore, the microphone includes a low-frequency roll-off filter and a switch to reduce proximity effect.

Acoustic Features:

The front segment of the U 87 Ai provides a flat response that remains uniform across the entire upper frequency range when used in cardioid and figure-8 polar patterns. This means it can be positioned close to the sound source without resulting in overly sharp or unnatural sound. Infrasonic and low frequencies interference is effectively suppressed thanks to the built-in low-frequency filter.

Polar Patterns:

The dual-diaphragm capsule is mounted on a flexible suspension and protected by a metal grille. The selector switch beneath it allows for easy switching between omnidirectional, cardioid, and figure-8 polar patterns. The pattern selected is indicated by a symbol displayed in the slot above the switch.

Filter and Attenuator:

The attenuator switch, located on the rear side of the microphone, reduces the microphone's sensitivity by 10 dB. When activated, the microphone can handle sound pressure levels up to 127 dB (equivalent to 45 Pa) without distortion. Another switch, positioned next to the attenuator, enables the selection of the cutoff frequency for the low-frequency roll-off filter, reducing the amount of low-frequency interference at the microphone amplifier's input. This filter is also useful in compensating for the proximity effect, which is characteristic of pressure gradient microphones when used in close proximity to the sound source.

Features:

• Microphone with large-diaphragm and switchable polar patterns
• Pressure gradient transducer, dual-diaphragm capsule
• Classic studio microphone
• Three polar patterns: omnidirectional, cardioid, and figure-8
• Low-frequency roll-off filter with switchable cutoff frequency
• 10 dB attenuator switch
• Ideal as a main or secondary microphone for a wide range of applications

Specifications:

• Capsule diameter: 56 mm
• Length: 200 mm
• Connector: XLR-3-F
• Maximum SPL: 127 dB
• Frequency range: 20 - 20000 Hz
• Nominal impedance: 200 Ohms
• Equivalent noise level (CCIR): 26/23/25 dB
• Equivalent noise level (A-weighted): 15/12/14 dB-A
• Maximum sound pressure level (THD 0.5%): 117 dB
• Signal-to-noise ratio (CCIR): 68/71/69 dB
• Signal-to-noise ratio (A-weighted): 79/82/80 dB

Package includes:

• Microphone
• EA 87 shock mount
• EA 87 Ai wooden box
• Documentation