RDL ST-HP3 300 Hz and 500 Hz High Pass FilterThe ST HP3 is the ideal choice where line level audio filtering needs to be provided at the input of a power amplifier for protection of public address horns against damage from low frequencies. The ST HP3 has one input and two filtered outputs: 300 Hz high pass and 500 Hz high pass. Both the input and output are balanced, and each may be wired unbalanced if required. The input accepts line level (+4 dBu nominal) audio. The module operates at unity