The Azden FMX-42a is a compact, four-channel portable mixer designed primarily for field production and electronic news gathering (ENG) with broadcast cameras. This mixer is engineered to provide professional audio mixing capabilities in a rugged, battery-powered package that can be easily mounted on a camera or carried on a strap. Its key feature is the 10-pin output connector, which is a standard interface for connecting directly to professional video cameras from manufacturers like Sony, Panasonic, and JVC, allowing for integrated control and clean audio feed into the camera's recording system. The mixer enables sound operators to combine and balance multiple audio sources—such as wireless lavalier microphones, handheld mics, and line-level feeds—into a clean, controlled stereo or mono mix before it reaches the camera, ensuring broadcast-quality audio capture in dynamic field environments.

Each of the four input channels is versatile, featuring combination XLR/TRS jacks that accept both microphone and line-level signals. Channels typically include gain control, peak LED indicators, and a 2-band EQ (high and low) for basic tonal shaping. Two of the channels often provide phantom power for condenser microphones. The mixer offers flexible routing, allowing inputs to be sent to the left, right, or both channels of the stereo output. The integrated 10-pin cable eliminates the need for separate audio cables and often enables camera control of audio levels from the mixer. Built for durability, the FMX-42a is housed in a robust metal chassis and can be powered by internal AA batteries or an external DC source, making it highly reliable for extended shoots away from AC power.

The mixer includes essential features for field work, such as a headphone output with volume control for monitoring, a slate microphone for adding verbal notes to recordings, and tone generator for level calibration. Its compact size and optional mounting accessories make it an indispensable tool for documentary filmmakers, news crews, and event videographers who require professional, multi-source audio mixing directly at the camera, streamlining workflow and significantly improving the quality and reliability of captured sound.