The Simple Reason Why You Can't Always Trust Loudspeaker Power Ratings

Have you ever blown a loudspeaker? If so, you've learned about loudspeaker power ratings the hard way. Many people believe a loudspeaker's power rating is mainly used to find out how far they can turn it up before they burn it out, which is one way to use it – but a power rating has many more uses than to test a safe volume limit.

From ultrasound devices in a hospital to a professional sound system in a concert hall, power ratings are crucial for creating a reliable, high-quality sound system for any application, regardless of the required sound level. A lack of agreed-upon industry standards can make it difficult to trust what's on the product label. However, with some knowledge and the proper manufacturer, you can be confident that the power rating on your product specifications is reliable.

What Does a Loudspeaker Power Rating Mean?

A loudspeaker's power rating is found in its specification sheet. Depending on the manufacturer and intended use, it's also sometimes called power handling, rated power, or continuous power.

By one definition, loudspeaker power ratings refer to how much power a loudspeaker is designed to safely receive from an amplifier. Power ratings are measured in watts, from 0.1W for small loudspeakers (think microwave beeping and children's toys) to 1000W for large loudspeakers (like PA loudspeakers), and generally scale with loudspeaker size and voice coil size. When used this way, a power rating can tell you about a loudspeaker's durability and reliability.

However, a power rating can also be defined as the point at which the loudspeaker begins to exhibit undesirable characteristics. This meaning is concerned with spurious noises, distortion, and power compression. Sometimes, overloading a loudspeaker's power rating can happen suddenly – it gets too hot too quickly, and much like how a fuse breaks or circuit breaker opens, the loudspeaker stops working. But you'll usually hear the effects of an inadequate power rating:

• Excessive distortion or noises
• Bottoming out (soft parts hitting hard parts)
• Power compression (putting in more electrical energy, but the loudspeaker doesn't get louder)
• Blown loudspeakers (voice-coil wire breakage)

The power ratings on many loudspeaker sellers' spec sheets are created by marketing departments rather than engineers, which leads them to be inaccurate or misleading. This phenomenon has given misleading power ratings a particular reputation among industry professionals, some of whom refer to them as marketing watts!

To make things a little more confusing, power rating standards for loudspeakers can vary widely because different industry organizations set them independently. For example, you may see three different styles of power ratings on three different loudspeakers, each equally valid but set by different industry groups like these:

• AES2-1984 (the Audio Engineering Society)
• EIA-426-B (the Electronic Industries Alliance)
• IEC 60027 (the International Electrotechnical Commission)

The loudspeaker manufacturer usually decides which power rating standard to use on their product. MISCO uses EIA-426-B, one of the most widely used power rating standards in the industry.

These organizations develop loudspeaker power rating standards using different test conditions, signal types, and levels. Unfortunately, this lack of a single standard makes it challenging for engineers to compare ratings set by different standards systems. Furthermore, most manufacturers use terms like maximum, peak, average, or program power handling without a clear reference point. If these terms aren't tied to published technical standards, they're open to interpretation – which can be even more confusing.

What a Power Rating Can't Tell You

Most significantly, loudspeaker ratings don't take the user's specific needs into account. What application the loudspeakers will be used, how they'll be enclosed, and even what input signal will be used can make a massive difference in understanding which power rating you need based on your product or application.

For instance, a military alarm loudspeaker may need to operate at a single frequency (like a sine or square wave) at very high power for an extended period in a challenging outdoor setting. Its power-handling requirements will differ from those of a full-range loudspeaker in a home hi-fi system that produces a wide range of frequencies (e.g., music or speech) at moderate listening levels in a controlled indoor environment. In this case, a higher power rating wouldn't necessarily improve the loudspeaker's function or efficiency.

To visualize the difference, look at this example of different signal types. Note the difference between their peak power requirement and root mean square (RMS), which measures the mean voltage to produce the sound.

In this chart, the power required to produce sound in the music track peaks for a short time and isn't sustained at that level for long. If you were to give a loudspeaker a power rating based on that peak, you'd be artificially inflating the power rating, and you'd need a lot of power to use the loudspeaker.

On the other hand, the audio in the sine wave more regularly reaches its peak, meaning a higher power rating would be required to support that consistent mean.

How to Make Sure You Get the Right Loudspeaker Power Rating for Your Application

Determining the right power rating for a loudspeaker is less about how much power it needs to produce sound and more about what power rating is appropriate for the ways it'll be used. Think of it like this: If Marty McFly from Back to the Future had understood power ratings a bit better, he wouldn't have exploded the enormous loudspeaker in Doc's workshop with his amp setting.

The frustrating truth is that the loudspeaker industry is on different pages about power ratings. That's because it's diverse and serves many markets, each with its own applications and needs, making it difficult to rely on power ratings for loudspeakers made specifically for other industries.

Power ratings should be considered reference points rather than fixed limits. To ensure you're choosing the right application, discuss what you need with your loudspeaker manufacturer. Show them your desired performance specifications and tell them about your application and priorities.

Discuss the input signal, loudspeaker enclosure, duty cycle, and whether their power rating is related to durability and reliability, distortion and power compression, or both. Are you willing to sacrifice some audio output in favor of long-term reliability? Or could the loudspeaker size change to ensure audio output and power handling can be met?

An open discussion based on how you'll use the loudspeaker will ensure you get a solution you can count on, made with your application in mind, rather than a less-than-reliable, one-size-fits-all product built to an unspecified standard.

Ready to Find the Right Loudspeaker for Your Needs?

At MISCO, we understand that power ratings can be confusing and selecting the right loudspeaker requires more than just a spec sheet. Whether you're looking for a solution in professional audio, aerospace, or specialized applications, our team of engineers is here to help. We take the time to understand your unique requirements and offer tailored solutions to meet your exact specifications.

If you’re ready to learn more or have any questions about our products, contact us today. Let’s work together to build the perfect audio solution for your project. Visit this page to contact us.

We look forward to helping you achieve exceptional sound performance!