Speaker Size vs Wattage
Is a 10-inch speaker louder than a 4-inch one? What if the smaller speaker has a bigger wattage rating? Does a higher wattage guarantee a louder or better sound? How does the size of a speaker come into play? What does any of it mean?!
The amount of ‘watts’ has become synonymous with speaker performance, with the common belief that the larger that number, the louder and better that speaker will be, but is that truly the case?
Whether you are buying PA speakers or setting up a home audio system, it's important to understand the difference between wattage ratings, the speaker's physical size, and how both affect the actual performance you should expect.
In this guide, we’ll take a look at speaker wattage, explore if bigger truly means better, and demystify technical terms like SPL and decibels.
WHAT IS SPEAKER WATTAGE?
A watt is a measurement of electrical energy. It has nothing to do with making sound. A lightbulb is measured in watts, a microwave oven, a kettle etc, all are measured in watts. It’s a measurement of that particular device's electrical consumption capability and is usually given as a maximum figure.
So, speaker wattage refers to the amount of power a speaker's components can deal with. This often confuses consumers who assume it’s a direct indicator of volume. However, wattage is more about how much electrical power the speaker can accept from an amplifier without distorting the sound or damaging itself from excess heat or movement beyond its physical capabilities.
To better understand, think of wattage as the fuel capacity of a car. Just because one car can hold more fuel than another doesn’t mean it will go faster, as performance capability is dictated by the physical and mechanical properties of the vehicle's components and how they can make use of that fuel supply. Some do it efficiently and some are wasteful.
Similarly, a higher-wattage speaker can handle more power going into its coil, but this doesn’t automatically translate to volume, as the speaker's physical capabilities and overall build quality come into play.
Wattage ratings for speakers are often provided in different formats just to add even more confusion, with RMS, Peak Power, or Max Power being the most common. RMS represents the continuous power a speaker can handle, providing a more accurate representation of its capability. Peak Power and Max Power, however, are both inflated ratings taken as extreme measurements. We go into these in more depth in the article 'Speaker power ratings explained'.
THE WATTAGE TO LOUDNESS RELATIONSHIP
One of the most common misconceptions is that a higher wattage rating on a speaker equates to a louder sound, which simply isn't the case. While there is a relationship between power and volume, it’s not as straightforward as it seems.
Does higher speaker wattage mean a louder sound?
Here's where it gets interesting: doubling the wattage doesn’t double the loudness. So a 200W amplifier for example isn't twice as loud as a 100W version, which is what many people would think.
The loudness of any device is measured in decibels (dB), not watts. Decibels are measured on what is known as a logarithmic scale, meaning that to double the loudness you need to multiply the energy (wattage) put in by a factor of 10.
So taking the same example of the 100W amp, doubling the wattage to 200W would only increase the volume capability by 3 dB (which is barely noticeable to the human ear). To make the output twice as loud as the 100W amp (a 10 dB increase), you would need to increase the wattage by ten times, so would need a 1000W amp.
Example: From the 1-Watt / 1 dB standard reference level
- A 3 dB increase will require double the amplifier power
- A 10 dB increase would be ten times the 1 Watt reference - 10 Watts of power
- 20 dB would be ten times that, so - 100 Watts of power
- 30 db would be ten times that - 1000 Watts of power
So ‘upgrading’ your 50W speakers to 150W isn't going to be the step up you think it will be, as the actual dB output change will barely be noticeable. To have double the output level you would need a 10 dB gain, so would need to go from a 50W speaker up to a 500W speaker.
For some context, silence is 0 dB, a whisper is 15 dB, a normal conversation between two people measures around 60 dB, while a jet engine or rock concert is around 120 dB.
OTHER FACTORS AFFECTING SPEAKER LOUDNESS
Speaker Sensitivity: This is a measure of how effectively a speaker converts power into movement. Measured in decibels (dB), it tells you how loud the speaker will be with a test signal played at 1 watt of power, at a distance of 1 metre. This then allows you to calculate maximum the output. Higher sensitivity equates to a louder sound for the same wattage.
It's such a crucial factor for a measure of a speaker's capability, as it shows how well it's going to deal with the power coming from an amplifier. For example, you could have two 10-inch speakers, both rated at 500W and looking identical. One has a sensitivity rating of 84 dB, while the other is 87 dB. This 3 dB difference in sensitivity seems small, but it’s electrically the equivalent of doubling the amplifier power, so is huge in terms of power efficiency and requirements.
To put that another way, the 84 dB speaker hooked up to a 500W amp may not even be audible until the amp volume is a quarter way up, whereas the 87 dB speaker will produce sound as soon as the volume dial is moved because it's far more sensitive. This allows the amp to run far more efficiently and means the 87 dB speaker will be significantly louder in use, despite having the same wattage rating.
Room Acoustics: The environment where the speakers are used significantly impacts the perceived loudness. A small, carpeted room will sound very different from a large, open space with hard surfaces.: The environment where the speakers are used significantly impacts the perceived loudness. A small, carpeted room will sound very different from a large, open space with hard surfaces.
Distance from the Speaker: Sound diminishes with distance. The farther you are from the speaker, the quieter it will sound. This is known as the inverse square law: doubling the distance from the sound source results in a 6 dB drop in sound level.
For instance, sitting a few metres away from a set of speakers in a living room requires significantly less power and dB output than listening at the opposite end of a hall or pub,as you have to raise the output level enough to counteract that natural drop in volume.
Impedance: Measured in ohms, impedance affects how much power the amplifier can deliver to the speaker. Lower impedance means more power, but matching the amplifier and speaker impedance is crucial to avoid damage. This is done for you in active speakers. We have a great article on matching speakers and amplifiers which covers impedance in more detail.
SPEAKER SIZE AND POWER RATINGS
The size of a speaker influences its power rating and performance characteristics. Larger speakers generally have bigger drivers and voice coils (the components that produce sound), which can convert more electrical energy and move more air, thus creating more substantial sound waves. This also makes them better suited for reproducing low frequencies.
For example, a 15-inch woofer can produce deeper bass than an 8-inch woofer given the same power. This is because the larger surface area of the 15-inch woofer moves more air with each vibration. The ability to move air is a huge factor in how a speaker delivers its sound into an area. However, size alone isn’t the only factor—how the speaker is designed and the quality of its components also matters significantly.
Power ratings and size are often correlated, as larger speakers can usually handle more power. This is partly because bigger speakers can dissipate heat more effectively through bigger coils and magnet venting, reducing the risk of thermal damage to the components at higher volumes. However, this doesn’t mean you should automatically opt for the largest speaker available. The best choice depends on your specific needs and the listening environment.
When looking at speakers you need to consider both the size and power rating in order to get something capable of both the sound pressure required and the ability to project that sound intact over a distance. For example, a 200W, 6-inch monitor speaker may be incredibly powerful for its size, but isn't going to produce deep bass or be able to project to a large hall. Similarly, you might have a 12-inch speaker that's only 80W, and despite its size, simply can't convert enough amp power to produce a decent SPL for good coverage.
For live music work, be it a band or a DJ, you should always be looking at 12” or 15” speakers and ensure they have both a good SPL rating and good wattage capability. You can use smaller speakers with separate subwoofer if preferred, though even those should be a minimum of 10” drivers to the top speakers as any smaller and they will struggle to project their sound in a larger venue, which also results in the subwoofer being over-present.
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5 DOES MORE WATTS MEAN MORE BASS?
Many people believe that higher-wattage speakers will produce more bass. While it’s true that power contributes to a speaker’s ability to reproduce low frequencies, wattage alone isn’t the determining factor. The design and size of the speaker, particularly the woofer, play a significant role in bass production.
Bass frequencies require more electrical energy to produce because they involve moving larger volumes of air, and a bigger physical movement of the speaker, which pulls more current from the amplifier than small movements.
Larger woofers can move more air, and when supplied with adequate power, can produce the deep, resonant bass that simply isn't possible for a smaller-diameter speaker. However, regardless of its physical size, increasing the amplifier power without considering the speaker’s design can quickly lead to distortion or worse.
Speaker enclosures drastically affect bass response. Ported (or bass reflex) enclosures can enhance low-frequency output by using a port or vent to improve efficiency at specific frequencies. This allows the speaker to produce more bass with less amplifier power. On the other hand, sealed enclosures offer tighter, more accurate bass but may require more power to achieve the same volume level as a ported design.
Environment is also a factor in bass response and the suitability of a speaker's size. Take a home cinema setup for instance, where an 8-inch hi-fi subwoofer will often be far more effective than say a 12-inch PA subwoofer at normal listening volumes. This is because at lower volumes, the smaller speaker is far more efficient in its use of power and driver movement, and its enclosure will be specifically designed to aid in low-volume bass response, while a larger speaker is barely responding at those low levels, so is actually moving less air than the more compact unit.
Swap that location to say a hall though, and the roles are reversed. The 8-inch will be ripping itself apart to be heard at a distance that the 12-inch will take in its stride. Even if they both had the same wattage rating and amplifiers, their effectiveness moves away from the electrical and becomes about physical air-moving capability, where the bigger diameter woofer wins.
While wattage contributes to the overall performance capability of a speaker, it’s the combination of power, speaker size, design, and enclosure type that determines the quality and quantity of bass.
6 WHAT ARE SPL AND DECIBELS?
As previously mentioned in section 2, Sound Pressure Level (SPL) is measured in decibels (dB) and is a critical concept in understanding speaker performance. SPL measures the air pressure of the sound waves from a device, using a scientifically determined test level to indicate the loudness of sound it’s capable of.
The sound we hear is vibrations at particular frequencies and levels of force in the air, interpreted by our ears. This is a measurable change with the right equipment, allowing us to rate things on their noise level. This rating can be a noise safety level warning for equipment such as power tools, or in the case of speakers, it's used as a rating of capability.
Decibels use a logarithmic scale, where a small increase in dB represents a significant increase in perceived loudness. For example, an increase of 10 dB roughly corresponds to a sound doubling in loudness. Understanding SPL and dB is essential for comparing the performance of different speakers and determining how they will perform in various environments.
SPL is tested by passing an audio signal through 1-watt of amplifier power into the speaker, which is then measured at a distance of 1 meter using a special microphone. For loudspeakers, it indicates how efficiently a speaker converts an electrical signal power into sound. A speaker with a higher sensitivity rating requires less amplifier power (wattage) to achieve the same volume as one with a lower rating.
This rating also allows you to determine the speaker's maximum SPL figure using the dB scale. For example, if you have a speaker that's rated at 100W maximum, and it produces a reading of 94 dB during the test, that 100W maximum is ten times the 1W test signal, so you will be gaining 10 dB, making the speakers maximum SPL 114 dB (94 + 10).
Wattage only tells you how much electrical power a speaker can make use of, whereas SPL tells you how much force that speaker is going to disturb the air with, which can then be compared to other noises for an accurate loudness reference.
7 ARE BIGGER SPEAKERS BETTER?
The age-old question: are bigger speakers inherently better? The answer, as with many things in audio, is — that it depends. Bigger speakers often have larger drivers, which can move more air to produce a louder output and deeper bass. They are also generally capable of handling more electrical power (wattage), which can translate to higher volumes and fuller sound in conjunction with the speaker's physical capabilities.
However, bigger isn’t always better. Large speakers may overwhelm smaller rooms, both in terms of required physical space and acoustic performance. They might produce excessive bass that drowns out other frequencies, or used at lower volumes will be far less dynamic and responsive than a smaller driver would be, leading to a less balanced listening experience.
In many cases, smaller speakers, either alone or paired with a good subwoofer, can deliver a well-rounded sound that suits a variety of environments and is far more detailed than a large-diameter speaker set. Advances in speaker technology have also led to compact speakers that pack a punch, offering high-quality sound and high SPL capability without the bulk.
Where large speakers come into their own however is area coverage, as their ability to move more air and carry the sound further requires those extra inches. For mobile DJs or live bands, your speaker's need for hi-fi quality sound is hugely outweighed by their need to be loud, and be loud across a large area for hours on end without burning out. This is where large driver size and higher wattage finally join hands and both become requirements to ensure the best results.
Ultimately, the best speaker size depends on your specific needs, the type of music or audio being played, and if they are for home audio or commercial use, but don't just assume that physically larger means better performance.
8 SPEAKER WATTAGE VS ROOM SIZE
Choosing the right speaker wattage for your room size is crucial for achieving optimal sound quality. A speaker that’s too large and powerful for a small room can lead to an overwhelming sound, or underwhelming and lacking detail at lower volumes. Conversely, a speaker that’s underpowered for a large space may end up distorted and unable to deliver the desired volume and clarity.
For smaller rooms such as bedrooms or home studios, speakers with lower wattage (20-50 watts) are usually sufficient. These speakers can provide clear and balanced sound without overpowering the space. Medium-sized rooms may benefit from speakers in the range of 50-150 watts. These can usually deliver enough power to fill the room without distortion. (either active speakers or passives with a well-matched amplifier).
Large rooms or outdoor areas require speakers with higher wattage (300 watts minimum, preferably higher) to ensure they can produce enough SPL to carry sound throughout the space. However, it’s not just about the wattage as already discussed, as many factors need to be considered, one of which is the dB loss that occurs over distances, which we touched on briefly in section 3.
Known as the 6 dB rule, it states that whenever the distance between you and the source doubles, the SPL decreases by 6 dB. As the SPL measurement is taken at a 1m distance, that is your zero loss point. At 2m away, you lose 6 dB. Being the same logarithmic scale this means the next 6 dB drop comes at 4m etc. This significant loss in audible output has to be considered and compensated for, which is why speakers for mobile work (DJs and live bands) must have enough power and SPL capability to allow for changes in room size.
9 FINAL THOUGHTS
Understanding the relationship between speaker size and wattage is essential for making an informed decision when purchasing audio equipment. While higher wattage can contribute to louder sound, it’s not the sole determinant of volume or sound quality. Speaker size, design, sensitivity, and the acoustics of your space all play crucial roles in achieving the best audio experience.
Remember, bigger speakers and higher wattage don’t always mean better sound. The right combination depends on your specific needs and environment. By considering factors such as speaker sensitivity, room size, and the type of audio content, you can find the perfect speakers to suit your preferences and enhance your listening experience.