Public Address (PA) systems are widely used in factories, schools, transportation hubs, and commercial buildings for announcements, background music, and emergency communication.

When designing a PA system, one of the most common questions is:

What is the difference between constant voltage speakers and low impedance speakers?

Both types are widely used in audio systems, but they serve different purposes depending on the size and requirements of the installation.

What Are Constant Voltage Speakers?

Constant voltage speakers are commonly used in large public address systems. These systems typically operate at 70V or 100V, which is why they are often called 70V/100V speaker systems.

In a constant voltage system, the amplifier outputs a high-voltage signal, and each speaker includes a built-in transformer. This transformer allows installers to select different power levels such as:

3W

6W

10W

20W

Because of this design, multiple speakers can be connected in parallel along the same cable line.

Advantages of Constant Voltage Systems

Easy to connect many speakers

Suitable for long-distance audio transmission

Flexible power distribution

Simple system design and installation

Typical Applications

Constant voltage speakers are commonly used in:

factories and industrial facilities

airports and railway stations

schools and campuses

shopping malls

parking areas and outdoor spaces

These environments often require large numbers of speakers and wide coverage areas.

What Are Low Impedance Speakers?

Low impedance speakers operate at 4 ohms or 8 ohms and connect directly to the amplifier without a transformer.

These systems are typically used in environments where sound quality is the main priority.

Advantages of Low Impedance Systems

Better audio quality

Direct connection to the amplifier

Efficient power transfer

Typical Applications

Low impedance speakers are often used in:

home audio systems

conference rooms

restaurants and bars

live music venues

theater and stage audio systems

However, these systems are usually designed for smaller installations with fewer speakers.

Constant Voltage vs Low Impedance: Key Differences

Which Speaker System Should You Choose?

The choice between constant voltage and low impedance speakers depends on the application.

Constant voltage systems are ideal when:

the installation area is large

many speakers are required

cable distances are long

the system is used for announcements or background music

Low impedance systems are better when:

sound quality is the highest priority

only a few speakers are needed

the installation area is relatively small

Conclusion

Constant voltage and low impedance speakers are both important in audio system design.

Constant voltage systems are the standard choice for large public address installations because they support many speakers and long cable distances.

Low impedance systems, on the other hand, are better suited for smaller audio systems where high sound quality is required.

Understanding these differences helps engineers and installers choose the most efficient solution for their PA system projects.