Heil Parametric Receive Audio System (PRAS)
The Heil Parametric Receive Audio System (PRAS) is a state-of-the-art audio system that enhances the internal audio systems of amateur radio, shortwave, commercial, and CB receivers. The PRAS 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.
Audio In Connections:
The PRAS has three audio inputs to connect to your receiver’s output:
— Standard 1/8”
— Standard XLR
— 8 ohm
Included with the PRAS is an 1/8”-to-1/8” male cable, and an 1/8”-to-1/4” adapter. The recommended method is to use this cable to connect the external speaker output of your receiver to the 1/8” audio input of the PRAS. When connecting, reduce the receiver AF output to 10 o’clock or lower. Alternatively, the PRAS can be connected via the audio out pins of the DIN connector in the accessory jack on your receiver’s rear panel. Check your receiver operation manual for assistance with your receiver’s audio outputs. The speaker output of your receiver can also be connected to the PRAS 8 ohm input.
Audio Out Connections:
The PRAS has three audio outputs to connect to external audio devices:
— Balanced XLR (rear panel)
— Mono 1/4” (rear panel)
— 1/8” Recording audio (front panel)
The PRAS is intended to be used with the Heil HPS-5 powered speaker (the PRAS must be used with a powered speaker). The HPS-5 consists of a 24-watt, two-way, low-distortion amplifier using a titanium midrange tweeter and a 5” low-frequency speaker. The HPS-5, in combination with the PRAS, provides superb audio balance without distortion. The PRAS comes with a XLR-to-XLR cable to connect to the HPS-5.
The PRAS also comes with an 1/8” output on the front panel to connect to any external recording device to record receive audio.
Two independent headphone amplifiers are included in the PRAS, each with its own 1/8” output and level control. Headphone outputs do not bypass the external audio out connections.
Heil Powered Speaker:
The Heil Powered Speaker (HPS-5) is a two-way, powered speaker designed to be used with the Heil Parametric Receive Audio System (PRAS). The HPS-5 in combination with the PRAS provides unmatched speech articulation and brings new dimensions to receive audio quality. The end result is a fantastic listening experience that relieves ear fatigue for operators.
The HPS-5 has a low-distortion, highly efficient Class A 24-watt amplifier that drives a specially designed 5” low-frequency speaker with a 3” magnet assembly mounted in a resonant sealed enclosure. A passive extended crossover drives a 2” high-frequency tweeter.
The HPS-5 has two rear panel inputs: a balanced 600 ohm XLR input and an unbalanced 1/8” input. A single level control adjusts the input signals for both inputs. There is also a balanced 600 ohm XLR output for combining two or more HPS-5 powered speakers. Dimensions are 9” H x 7” W x 6” D.
The PRAS is powered by an included 12-volt DC power supply and a 12-volt coaxial Y cable.