The Heil Parametric Receive Audio System Equalizer (PRAS EQ) is a state-of-the-art audio processor that enhances the internal audio systems of amateur radio, shortwave, commercial, and CB receivers. The PRAS EQ allows radio operators to modify, shape, and improve the audio output of their receivers using three separate equalization controls.

Midrange frequencies are the most critical for achieving clear voice articulation in receive audio. The PRAS allows operators to have unique control over these important frequencies. First, operators can adjust the parametric midrange filter (MID FREQUENCY) from 400 Hz through 4 kHz, with the recommended sweet spot being at 2.5 kHz. In addition, operators can control the presence of these midrange frequencies plus or minus 15 dB using the MID GAIN control. Combined with a low-frequency filter (LOW) set at 160 Hz, and a high-frequency filter (HIGH) set at 6 kHz, the PRAS provides operators unparalleled control and quality of their receive audio.