How Do 70 Volt Horn Loaded PA Speakers Work on Pro Acoustics Tech Talk Ep 81


In this video, Nathan explains how PA horn speakers work and when and where you might want to use them.

Today’s paging and announcement horn speakers provide intelligible voice, paging, public address, and tone signaling for indoor and outdoor PA sound systems. Made to run 24/7 and last in challenging environments, commercial outdoor horns are UV resistant and weatherproof. Horn loudspeakers offer excellent frequency response, coverage, and high dB output. One of the most popular reasons to use a horn speaker is that you need it to get really loud at an affordable price and cover a large area.

As long as the concept may have been around, most people don’t know how these speakers actually work.

The most recognized characteristic of a horn speaker is its shape. These are the 3 parts of a horn speaker that make up this shape.
1. Throat: The part that is connected to the speaker/driver
2. Neck: The length of the horn
3. Mouth or bell: The larger end part of the horn, “connected” to the air

The horn expands from the throat to the end of the mouth.

In principle, horn loudspeakers work the opposite way of the human ear. Sounds that come into the outer ear gradually decrease in size down to the eardrum, gradually increasing the sound pressure and making it easier for us to hear. Horn speakers, work the other way around. A driver is placed at the beginning of the horn, or throat, that transforms the pressure produced by the horn shape and radiates it out of the mouth.

A speaker has a high impedance, versus the air, which has a low impedance. The taper or flare shape of the horn acts as an impedance transformer making a smooth transition from the high to low impedance and the low electrical power into high sound levels.

The horn is passive and does not add additional energy/power to the system. Similarly, if you cup your hands around your mouth your voice can be radiated further and louder.

The larger the diaphragm of a speaker, the more air will be moved and the greater the sound pressure/louder the audio. By using a flared horn the effective sound coverage from a driver is increased creating louder sound, increased SPL, and greater directivity.

Horns can also have compression chambers that alter the frequency of the horn and change the operation of the driver.

Some horns are used as waveguides to direct the dispersion pattern of the speaker. Constant Directivity (CD) horns provide constant dispersion across the entire bandwidth so you still hear the same sound in all locations the speaker is covering.

There are certain advantages compared to other loudspeaker systems.

The Benefits of a Horn Speaker
- Highly improved efficiency - doesn’t need a lot of wattage
- Eliminates the resonance or rattling introduced by speaker boxes
- Increased directivity
- Reduction of distortion
- Focus on vocal range frequencies for long-range & high output at low volumes (but not great for music as a result)

These benefits make horn speakers great for paging, voice, and emergency signal distribution for warehouses, parking lots, public transportation stations, public buildings, parks, stadiums, airports, hospitals, schools, emergency evacuation, and industrial public address sound systems.

There is a wide variety of 8 ohm and built-in 25V/70V transformer versions available. The Yorkville C180 Coliseum outdoor PA horn and Atlas Sound GA-15T horn loudspeakers are 2 examples. Both of these have relatively small throat sizes, so as a result, you get less low (bass frequencies), but still high output. To get a very deep full-range sound you need a large horn.

Have any additional questions about horn-loaded pa speakers? Let us know by commenting below, emailing [email protected], or calling (888) 256-4112.

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Featured In this video:
Yorkville C180 Coliseum Mini-Series Outdoor PA Horn

Atlas Sound GA-15T Re-Entrant Horn Loudspeaker with 25V / 70.7V 15W Transformer
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