The BSS DPR 901 II is a sophisticated professional audio processor that uniquely combines the functions of a parametric equalizer and a dynamics controller into a single, integrated unit. This dual-channel device allows engineers to apply frequency-conscious compression or expansion, meaning the dynamic processing is selectively applied only within specific, user-defined frequency bands. Each channel features two fully independent dynamic EQ bands alongside a standard parametric EQ section, enabling precise control over problematic resonances, feedback prone frequencies, or dynamic imbalances in a mix. For example, it can compress only the harsh mid-range of a vocal when it gets too loud, or expand the low-end of a bass guitar to add punch during quieter passages, without affecting the rest of the audio spectrum.

The unit provides comprehensive control over all parameters, including center frequency, bandwidth (Q), threshold, ratio, attack, and release for each dynamic band. This level of detail makes it an invaluable tool for critical live sound reinforcement, broadcast processing, and studio mastering applications where traditional broadband compression is too crude. The DPR 901 II is renowned for its transparent, musical sound and robust analog circuitry, housed in a single rack unit. It features balanced XLR inputs and outputs, comprehensive metering via LED ladders for input, output, and gain reduction per band, and the ability to link its two channels for stereo operation.

Designed for audio professionals who require surgical dynamic control, the DPR 901 II excels at tasks like feedback control, tonal balancing of erratic sources, and creative sound shaping. Its ability to dynamically manage specific frequency ranges, rather than the entire signal, makes it a powerful and nuanced tool for achieving a polished, controlled, and natural sound in the most demanding acoustic environments.