RDL ST-HP3 300 Hz / 500 Hz High-Pass Filter – Balanced Line-Level Input Dual Filter Outputs

Description

The ST-HP3 is a compact dual high-pass filter module designed to protect horn loudspeakers by removing damaging low-frequency content. It accepts a balanced line-level input and provides two filtered balanced outputs at 300 Hz and 500 Hz. The module operates at unity gain and permits simultaneous use of both outputs.

Key features include two fixed high-pass outputs at 300 Hz and 500 Hz and an 18 dB/octave attenuation curve that reduces low-frequency energy below each cutoff. The inputs and outputs are balanced and may be wired unbalanced if required, preserving installation flexibility. The device requires no field adjustment, delivering consistent filtering performance out of the box.

Performance specifications include a nominal input impedance of 20 kO, output impedance of 150 O, headroom greater than 18 dB and THD+N below 0.01%. The 300 Hz output provides a frequency response of 300 Hz to 30 kHz (±0.5 dB) with a -3 dB point at 225 Hz. The 500 Hz output provides a frequency response of 500 Hz to 30 kHz (±1.0 dB) with a -3 dB point at 450 Hz.

Connectivity is straightforward – a single balanced line-level input feeds two balanced line-level outputs that may be used simultaneously. The module operates from RDL SupplyFlex power input allowing ground-referenced, floating or bipolar 24 Vdc supplies at 30 mA. Installation requires standard line-level cabling and offers wiring options for balanced or unbalanced configurations.

Typical applications include public address systems using horn loudspeakers where low-frequency protection is required, tone and paging systems that must avoid amplifier and driver overload, and fixed installations in houses of worship, transit hubs or stadium concourses. The ST-HP3 integrates into racks and distributed audio systems where reliable passive filtering is preferred. It is especially useful where fixed, repeatable filter characteristics are required without onsite tuning.

The ST-HP3 is housed in a compact module form factor with dimensions suitable for rack or enclosure mounting and simple wiring. It is designed for continuous operation in ambient environments from 0 C to 55 C and ships in a compact cardboard box. With minimal insertion loss and robust electrical characteristics, the ST-HP3 provides predictable protection and straightforward integration into professional audio systems.