The DPR-504 is a 4-channel noise gate.

Each channel features:

A parametric key filter with key filter listening.

Simultaneous key level and threshold metering with average and peak metering.

A gate status LED.

A RELEASE/HOLD control (hold tracks proportionally with release times).

Attack switchable auto/fast (auto tracks signal dynamics for optimum setting).

Link (links two channels together).

Key source allows external triggers.

The Range switch selects between 7OdB and 2OdB gating depth to provide alternative release profiles.

The unit features electronically balanced inputs and outputs.