An affordable reference mic you can build yourself

Reference mics are essential tools for audio work. They are valued for their flat frequency response and are often used to characterize the audio response of a room or space. OpenRefMic aims to be an open source design to produce reference mics without paying exorbitant retail prices.

The heart of the construction is a preamplifier that operates with standard 48V phantom power and is responsible for both biasing the electret microphone element and buffering the mic signal . It is specially designed to work with the PUI AOM-5024L-HD-F-R microphone capsule, chosen for its good performance and low noise characteristics. However, other electric pickups should also work. The hardware is packaged in a 3D printed case that can easily be made on most basic printers. It has a snug fit grille that keeps the mic capsule in place.

The main focus of the project is low noise; The creator of the project, [loudifier], notes that most commercial reference mics focus on flat frequency response first, then noise reduction. OpenRefMic performs well in this area, and its lack of a perfectly flat frequency response is countered by calibrated equalization. It also works with pro-grade XLR cables and phantom power, rather than the need for fancy lab cables and interfaces.

The end result is credit to [loudifier], who demonstrates a solid understanding of reference mic design principles. We've also seen some other great low-cost reference mics lately!