The Comrex DH20 is a professional-grade digital hybrid unit and audio interface engineered specifically for broadcasters to deliver high-quality, reliable audio over standard telephone lines and IP networks. It serves as a critical link between studio mixing consoles and the public switched telephone network (PSTN), enabling clear interviews, call-in segments, and remote broadcasts by effectively converting the two-wire telephone circuit into a stable, high-performance four-wire studio connection. The device is renowned for its advanced acoustic echo cancellation and noise reduction algorithms, which suppress line noise, hum, and the acoustic echo that occurs when a caller hears the studio broadcast feed through their own handset or speakerphone, ensuring that on-air conversations are crisp, intelligible, and free of distracting artifacts.

Functionally, the DH20 operates as both a traditional telco hybrid for POTS (Plain Old Telephone Service) lines and a sophisticated audio codec for IP connections via Ethernet. It features two independent hybrid/codec channels, allowing broadcasters to manage two separate phone calls or remote contributions simultaneously. The unit provides extensive control and monitoring, including programmable presets for different line conditions, a comprehensive front-panel meter bridge for levels, and built-in test tone generators for line-up. Its audio performance is tailored for broadcast, offering wide bandwidth, low distortion, and the ability to handle high levels without clipping, making the most of the limited frequency range of a telephone connection.

Designed for rack-mount installation in broadcast trucks and studio racks, the DH20 is built for durability and ease of use in fast-paced production environments. It supports various connectivity options, including analog XLR inputs/outputs, RJ-11 telephone jacks, and Ethernet for IP audio streaming using Comrex's own proprietary BRIC-Link technology or other standard codecs. By combining robust telephone line interfacing with modern IP audio capabilities in a single unit, the Comrex DH20 provides broadcast engineers with a versatile and trusted tool for integrating remote voices into live programming with the clarity and reliability demanded by professional radio and television stations.