The Shure A400SMXLR is a professional shock mount accessory engineered for the Shure MX400 Series of boundary layer microphones, such as the MX391. Its primary function is to mechanically isolate the microphone from vibrations and structural noise transmitted through the surface on which it is placed. In applications like conference tables, lecterns, or pulpits, these unwanted vibrations from tapping, footsteps, or equipment handling can be picked up by the microphone and amplified as low-frequency rumble, degrading audio clarity. The shock mount suspends the microphone within a system of elastic bands, effectively decoupling it from the mounting surface and allowing the microphone to capture only the desired airborne sound waves, such as speech.

The mount is designed for secure and discreet installation. It typically attaches to the surface via an adhesive base or mounting screws, providing a stable platform. The MX400 series microphone then clips securely into the suspended cradle. This design ensures the microphone maintains its optimal position and orientation for boundary layer operation, where it utilizes the reflective properties of the flat surface to enhance sensitivity and provide a hemispherical pickup pattern. The integrated design includes a female XLR connector built into the base of the shock mount. A short, permanently attached male XLR cable extends from the mount, providing the audio output and ensuring a reliable, strain-relieved connection that minimizes cable movement at the microphone terminal.

Constructed from durable materials, the A400SMXLR is built for longevity in permanent or semi-permanent installations. The elastic suspension system is designed to maintain its tension and isolation properties over time. By effectively eliminating structure-borne noise, this shock mount significantly improves the audio quality of the boundary microphone in demanding acoustic environments. It is an essential companion for the MX400 series in boardrooms, courtrooms, houses of worship, and any setting where clear, intelligible speech reinforcement is critical and where the microphone must be permanently installed on a surface subject to incidental contact and vibration.