Speaker sensitivity is a topic that is often overlooked when purchasing speakers, yet it remains one of the most important factors to consider when deciding what type of speaker you should be buying. Most speakers fall into a range of around 80-92dB in sensitivity.
Speaker sensitivity is written as a number of decibels. This value typically represents how much volume the speaker can put out with 1W of power and how efficient the speaker is at turning power into volume. Speakers with higher sensitivity will need less power to drive them, and for home audio, this relates primarily to your amplifier.
Sensitivity as a concept exists across all types of speakers, with Bluetooth speakers, home audio, and even headphones all having a sensitivity rating attached to them. In the case of headphones and Bluetooth speakers, which utilize an onboard amplifier, you won’t need to pay too much attention to sensitivity. However, it can still help you gauge the total volume output potential. However, for home audio, where you will be matching your speaker with an amplifier yourself, sensitivity becomes more important to consider as a consumer.
How Speaker Sensitivity Works
Since the sensitivity tells us how much volume a speaker can produce with 1W of power, we can use that math to calculate how much total volume a speaker can produce by multiplying it with the amplification. You’ll need to double your power input for every 3dB of volume you want to add.
Let’s assume we have a speaker with an 85dB sensitivity rating (1W @ 1 meter). If we increase the amplifier from 1W to 2W by doubling it, you’ll achieve a volume level of 88dB. If we want to increase the volume further, we can add another 3dB of volume by doubling our amplification from 2W to 4W. Following this same principle, the speaker becomes exponentially more difficult to increase the volume in terms of amplification. If we wanted to push the volume on this particular speaker to 120W, it would require us to pair it with an amplifier that has a continuous power of 32W.
The following math equation is used to draw a correlation between speaker sensitivity and maximum volume potential: Sensitivity + 10log(Power) = Max Volume
Keep in mind that you cannot just continuously increase the amplifier power endlessly. Overpowering your speakers can destroy speakers. Consider the amplifier ratings for your speaker when looking at sensitivity, as these two numbers together can help achieve a better idea of your maximum volume limit.
Let’s take the JBL Professional Control 128W, one of our favorite in-wall speakers. These speakers have a sensitivity of 90dB (1W @ 1m) and a continuous power rating of 120W. From here, we can calculate the maximum volume possible, assuming we use all 120W of power.
If we plot each time occasion where we double our power until we reach our maximum power input (120W continuous in this case), we can see that the maximum volume output for the JBL Control 128W is just shy of 111dB. This assumes that one is using an amplifier with the correct impedance.
Low-sensitivity speakers are not worse than high-sensitivity speakers, and both can produce the same types of volume. Still, the low-sensitivity speakers will require more juice to do so. The graph below illustrates the power requirement in relation to the speaker sensitivity rating, comparing an 80dB sensitivity speaker with one of 92dB. Let it be noted that
You can see that the 80dB sensitivity speaker (Orange) required a total of 256W of power to achieve a volume output of 104dB, whereas the 92dB speaker (Blue) only required 8W of power to achieve the same volume.
How Does Sensitivity Affect Audio Quality
While speaker sensitivity is most closely related to volume, your speaker’s sensitivity can also affect your overall audio quality and sound experience. Not all high-quality speakers have high sensitivity, and not all low-sensitivity speakers are bad. Some benefits come with low sensitivity; with all speaker engineering, it comes down to finding the sound you want to create.
Have you ever noticed how unique speakers are in their sound? You can grab two speakers from the same market and compare them, you’ll rarely ever find two that sound identical next to each other, and that’s because speakers are complex and made up of a number of different parts, each bringing their qualities forward in the listening experience.
Here’s how sensitivity can impact your listening experience:
Speakers with lower sensitivity can often provide a better bass response, as they require more power, resulting in a tighter and more controlled bass. On the other hand, high-sensitivity speakers can be prone to a looser bass sound. This isn’t always the case, and one needs to consider other factors in constructing the speaker and the driver.
Still, as you increase the sensitivity of your speaker, there is a relational drop in the presence of the bass (one loses 1 octave of bass for every 3dB of sensitivity). This drop needs to be compensated for in other areas of engineering. Increasing the size of the speaker housing is one way to help compensate for a decline in the bass, but this scales up quickly, becoming impractical.
Speakers that have higher sensitivity tend to offer a better dynamic range. Dynamic range is the amount of detail the speaker can accurately represent. This isn’t to say a high sensitivity guarantees a great deal of nuance or is objectively better, as more than just the sensitivity plays a role here. Still, if you have a speaker with high sensitivity, you will likely achieve a better dynamic range performance. There is a balance to be found here, as excessive dynamic range can create a loss of audio quality due to the stark contrast between loud and soft areas.
Another area of sound where you’ll notice sensitivity playing a role is in the transient response of the audio. This refers to how quickly and effectively the speaker can play rapid changes in sound. In practice, this works somewhat similarly to latency in the fact that even minimal delays in the transition of these sounds can impact the overall audio quality, with lower transient response rates resulting in a cleaner, more realistic sound.
It is worth noting that high-sensitivity speakers will be more prone to distortion since they are easily overpowered. This is something that can be avoided, however. As long as you ensure you are using the correct amplifier for your speakers and are driving them with the correct power, you shouldn’t notice distortion issues in your listening.
What Affects Speaker Sensitivity
Speakers comprise various components that work together with power input to provide a unique sound experience. These changes in design heavily influence your listening experience. Speaker sensitivity is also greatly affected by how a speaker is constructed.
The design of the driver itself will impact sensitivity. If we dig into the driver’s construction a bit, we can further point out a few factors that will impact your overall sensitivity.
The first variable is the speaker’s cone design. Because speakers create sound by pushing the air with the driver cones, changes in the materials used for the cone will make them either easier or harder to push. Speakers that have stiff driver cones will typically perform better in low-end response but may have less sensitivity and, in turn, can be harder to drive, depending on the materials used.
For engineers, it’s about finding a good balance between a cone that is easy to drive and retains the audio’s integrity. Cones that are pushed too hard for their material type can result in the cone losing their shape during use, resulting in negative audio traits such as crunching or rattling. Materials like titanium or aluminum are commonly used in cone designs, but there is still a lot of variability between manufacturers and individual products.
The magnet inside the driver forms another piece of the puzzle as it, too, can impact the sensitivity of a speaker. Larger drivers are typically able to provide more sensitivity to a speaker design. That’s not to say that all speakers with smaller driver magnets will have lower sensitivity, as one needs to keep in mind that a range of different elements are all working together to find the best balance in sensitivity (after all, more isn’t always better).
The voice coil design will also affect the sensitivity performance of speakers. Not only does the voice coil’s length and thickness affect the sensitivity, but the way in which the coil is wound will also have an impact. Voice coils and their performance are ultimately related to the coverage and contact the coil provides. One can even see improvements in sensitivity when the voice coil uses a flat wire design instead of a round one, as the flat surface increases the surface area coverage.
This doesn’t mean the best sensitivity comes from the thickest wires because the opposite is true. We tend to see better sensitivity ratings on speakers with thinner but longer voice coils. Not all voice coil wires are the same; some are more efficient than others. Typically, steel voice coils will provide lower efficiency, while aluminum and copper are popular choices for increasing sensitivity.
Is More Better?
No. Despite the benefits of having a good sensitivity speaker, simply looking for the highest number possible is not a good approach. A high sensitivity does not guarantee a good-sounding speaker, and sometimes too high of sensitivity can have its own problems as a result.
One of the most noticeable sacrifices one has to make is in the bass response. For every 3 decibels of efficiency, one essentially loses an octave of bass, which can be compensated for by adjusting the driver’s enclosure to make it larger, but this is done on a manufacturer level, and it quickly becomes a losing battle as one ramp up the sensitivity.
While we’ve covered speaker sensitivity to a fair extent, it’s useful to understand that speaker engineering comprises various components, each playing a role in how the speaker performs. Just because a speaker has high sensitivity does not necessarily mean it will sound better than one with lower sensitivity. It will just be easier to drive. That said, when you have a high speaker sensitivity matched with well-tuned engineering, you can also reap the benefits of the impact of sensitivity on overall performance.
If you feel we’ve missed something or have any questions – we welcome your input in the comments below.