The BSS DPR 504 is a professional four-channel noise gate processor designed to provide precise control over low-level noise in live sound, broadcast, and studio environments. Housed in a single rack unit, each of its four channels operates independently, allowing engineers to apply gating to multiple microphones or audio channels simultaneously, such as drum microphones, vocal mics in a noisy stage environment, or any source with unwanted ambient noise or bleed. The gate utilizes advanced detection circuits with key filtering to accurately differentiate between the desired signal and background noise, ensuring that the gate opens and closes musically and transparently without chopping off the tails of sounds or creating audible artifacts.

Each channel offers a comprehensive set of controls including threshold, attack, release, hold, and range parameters, giving the user fine-grained command over the gating action. A key feature is the side-chain filter section, which allows the gate's trigger signal to be filtered (high-pass and low-pass), enabling it to respond specifically to the frequency content of the desired source—for example, gating a snare drum mic based on the snap of the drum while ignoring the bleed from the hi-hat. The unit provides both input and gain reduction metering via LED ladders for clear visual feedback on signal levels and gating activity. Connectivity is professional with balanced XLR inputs and outputs.

Built with the robust analog circuitry and reliability associated with the BSS brand, the DPR 504 is a dedicated tool for cleaning up mixes and improving clarity. Its quad-channel design makes it an efficient solution for managing noise on multiple channels from a compact, rack-mountable unit, making it a valuable asset in both front-of-house and recording studio signal chains.