APPLICATION SPOTLIGHT

Do you need an effective way to roll off unwanted low frequencies for a paging system?? This week’s Application Spotlight explains a very simple and cost-effective way to accomplish this using RDL’s ST-HP3 High Pass Filter.

Some audio systems simply don’t need to produce excessively low frequencies, and in some cases low frequencies can impede their performance and effectiveness. ?Paging systems designed with paging horn speakers are a good example.? These horns are used when the primary audio source is voice, which has an audio spectrum range between 300 and 3000 Hz. This range is often called the voice frequency or voiceband. ?Paging in this range is essential for transmission of intelligible speech, especially when distributing announcements in large or noisy environments such as warehouses, factories, shop areas, outdoor venues, parking lots, even some retail stores. ?Plus, the voice coils in paging horn compression drivers are easily destroyed by excessively low frequencies.

The ST-HP3 has one input and two filtered outputs at 300 Hz and 500 Hz high pass.? Installers can choose one or the other depending on the frequency response of the installed paging horns or use both simultaneously to feed multiple zones with different sized horns.? Using the ST-HP3 can save a lot of installation time and labor by eliminating the need for calculating and installing a capacitor on each driver, and it provides a steeper attenuation slope for better protection and intelligibility. ?Low frequencies are attenuated by 18 dB per octave below the selected cutoff frequency.

The ST-HP3 can also be used in audio systems that have full range loudspeakers if there is a paging override feature.? The high pass filtered paging signal will effectively cut through a noisy environment such as a bar or restaurant.?

In this system example, the ST-HP3 is installed prior to the input of the power amplifier for a parking lot PA system, which protects the voice coil by attenuating low frequencies, and it allows more of the amplifiers energy to produce audio in the effective voiceband range. The installer chose the 300 Hz high pass filter output, which ideally matches the frequency response of the installed horns. ?Announcements can be clearly heard throughout the entire parking lot regardless of any normal activity taking place.

CLICK HERE for More Details: ?AN-2196.pdf

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