Simply put, the most important part of headphones is the driver. It’s the part responsible for taking the audio signals and turning them into sound waves. Without a driver, there would be no sound for you to hear.
Drivers come in a range of sizes and designs. Typically, in-ear headphones have drivers of 8-15mm in diameter. On-ear and over-ear headphones have more real estate and can fit drivers ranging from 20-50mm. The driver size is largely dependent on the type of headphones. But as you can see, there is a range of sizes within each headphone style.
So what is a good driver size for headphones? To answer this, we need to know how driver size affects sound quality. But first, we’ll look at exactly how headphone drivers work.
How Do Drivers Work?
Dynamic drivers are by far the most common headphone drivers, so we’ll take a look at how they function. More information on other driver types will come later in the article.
Three main dynamic driver components function in unison to create sound. A magnet, voice coils, and a diaphragm. The neodymium magnet is responsible for producing the static magnetic field that, in turn, magnetizes the voice coil. This then allows the voice coil to move quickly back and forward when it receives an audio signal.
As the diaphragm is attached to the voice coil, it moves too. Displacing the air around it and thereby creating an audible soundwave.
Driver Size and its Effect on Headphones
The size of a driver (its diameter) does affect the sound produced. Essentially, the larger the driver is, the more sound or volume it can produce. This explains why earbuds have small drivers, and over-ear headphones have larger ones.
Because earbuds are positioned inside the ear much closer to the eardrum, they don’t need to produce the same level of output as standard headphones. It’s all about proximity to the eardrum.
To avoid damaging your hearing, earbud drivers have to be smaller, especially as they create a seal inside your ear canal. This means less of the sound will leak, and more of it will be directed at the eardrum.
Sound waves work on a sliding scale…
The sound pressure levels of these waves will reduce by six decibels every time the distance is doubled. Over-ear headphones are significantly further away from your eardrum. Therefore, they need larger drivers to displace more air as the wave has a longer distance to travel.
Driver Size and its Effect on Sound Quality
It’s a common misconception that as driver sizes get bigger, so does the quality of the sound. This is not always the case, as there are many other factors at play here.
It’s fair to say that a larger driver affects bass reproduction. Because they can push more air, they can produce louder, more impactful bass. But that doesn’t necessarily mean the quality of that bass will be higher. Bigger drivers can sometimes struggle to reproduce high frequencies too.
A bigger driver can certainly produce more output, but the quality of that output is determined by several things. So, when asking, “What is a good driver size for headphones?” the answer is going to be, “That depends.”
Component quality is king…
As discussed earlier, drivers have several different components, the quality of which is of paramount importance. A driver is constructed with low-quality materials can lead to distortion and potential damage.
Cheap materials can struggle at high volumes, leading to blown speakers, something that’s probably happened to us all. Flexible, high-quality driver materials are essential in reproducing undistorted sound and will also be able to handle high power levels without breaking.
Tuning and Design
Another important factor is the frequency response or tuning of the headphones. This is an art form in itself. It means the design and arrangement of all the other components and materials around the driver will help produce the desired frequency response. Whilst also keeping distortion to a minimum.
Headphone housing design and material quality can also contribute or detract from the overall sound quality. As drivers push out air in both directions, enclosed headphones need to have an effective housing design. One that will minimize the sound firing away from your ear.
The type of material used in the pads on the earcups of over-ear headphones also affects sound performance.
There are also a few technical factors that make a huge difference to sound quality. None of which have anything to do with the size of the driver. Headphone sensitivity and impedance are two of these.
Two headphones may have the same driver size, but the sensitivity and impedance levels may differ. In this scenario, if the same audio signal is channeled through both, the outcome will be vastly different. The driver with lower sensitivity and more impedance will require more voltage to make the diaphragm move.
Small drivers can compete…
So, in terms of audio quality, big isn’t necessarily better. Well-designed headphones with a small driver made from top-quality components are more capable of higher fidelity than a bigger driver made using poor-quality materials.
That being said, combine larger drivers with the factors mentioned above, and this is where you’ll find the highest quality audio that headphones can offer.
We’ve looked at how dynamic drivers work already, so we’ll touch on what they offer only. They are good at amplifying bass due to their capability to displace air powerfully and perform well in the mid-range too.
There is a major downside, though. At high volumes, they are prone to distortion, but this is nothing that clever engineering can’t sort out. So much so that some of the most expensive headphones out there use dynamic drivers.
Balanced Armature Drivers
These are the smallest headphone drivers and are found in earphones only. Two magnets house an armature or magnetic coil. As the audio signal is applied, the magnets are repelled or attracted by the coil. This vibrates the diaphragm to create sound.
Balance armature drivers aren’t very good at reproducing bass. That is why manufacturers usually combine them with a dynamic driver to make up for it. A good example of this is the excellent 1More Triple Driver earphones.
What they do offer is excellent high-frequency reproduction for a very detailed experience. Especially when combined with a dynamic driver to handle the bass.
Planar Magnetic Drivers
These are usually found in high-end, open-back, audiophile-grade headphones and can have diameters from 50mm to 110mm. Planar magnetic drivers also function through the creation of a magnetic field.
The diaphragm, in this case, is sandwiched between two magnets and receives the audio signal via a laced wire. On receiving the signal, the diaphragm and magnets react to create movement and, subsequently, sound.
And what a clean and accurate sound they create! If you want exceptional sound quality with zero distortion, even at the highest volume, planar magnetically driven headphones are the way to go. Audiophiles swear by them. Unfortunately, they don’t come cheap.
You’ll need a second mortgage to buy headphones with electrostatic drivers. That’s why you usually only find them in studios.
An electrically charged diaphragm lies between two metal plates or electrodes. The electrodes receive the audio signal and are then electrified. This pulls and pushes the diaphragm with amazing accuracy. Resulting in the clearest sound reproduction out of all driver types. These are for professionals and rich audiophiles only.
Right then. It’s now time to revisit our original question.
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What Is a Good Driver Size for Headphones? – Conclusion
So now we’ve seen that driver size is no indication of the sound quality of headphones. There is no correct answer to this question. You need to be looking at the quality of the entire product rather than just the size of the driver.
As a rule, the bigger the driver, the more power it will output. Especially in the low end of the frequency range. If you want a clean, undistorted sound to go with that extra power, make sure quality materials are used throughout the construction of the headphones. In fairness, the same rule applies to smaller drivers too.
Driver type makes a difference, but for your average consumer, planar magnetic and electrostatically driven headphones are too expensive. As a result, most will opt for dynamically driven headphones.
Finally, if you take one thing from this article, let it be the golden rule. Better audio quality doesn’t come by increasing the driver size. If only it were that simple.
Until next time, happy listening.