The document provides an overview of the controls on the dbx 904 unit, including ATTN LIMIT, RATIO, THRESHOLD, ATTACK, and RELEASE knobs. It explains how these settings affect attenuation levels and the speed at which the device enters or exits noise-gating modes.
The maximum attenuation is at least 60 dB, though it is typically somewhat more due to circuit design.
The input impedance is 25 k-ohms for balanced audio connections.
The control characteristic is a convenient -50 mV/dB (-20 dB/V).