If ever you’ve found yourself buying a pair of high-quality headphones, you’ve probably met a couple of terms that might sound complicated and difficult to understand.
For people who aren’t really well versed with headphones, two of those terms are impedance and sensitivity.
Both of these terms are actually important when you’re picking a pair of headphones, so to make sure you don’t make a mistake, we’ll take a look at what both are. We’ll explain what the impedance and sensitivity have to do with not just the headphones, but the amp/DAC as well.
What is Headphone Impedance?
The first thing you want to know is that impedance is probably the most important term to know when it comes to picking a pair of headphones.
It’s something that not only affects the headphone’s character, but impedance is what determines what source you’ll need to play the headphones. And it’s rather easy to explain.
Basically, impedance is electrical resistance.
The number indicates how much resistance a device will have to the electrical current that passes through. Wikipedia’s definition says impedance is a “measure of the opposition that a circuit presents to a current when a voltage is applied”, and there’s no better way to explain it.
It is measured in ohms (Ω), and each pair of headphones has a predefined impedance number. And that impedance will determine just how much power you’ll need for your headphones in order for them to get to a decent listening volume.
Why does Impedance matter that much?
And when it comes to impedance, the higher the number, the more power you’ll need to drive those headphones. A smartphone might not cut it for some power-hungry headphones. Even at maximum volume, you’ll find things are a tad quiet, and you may even start hearing artifacts, which nobody likes.
Now, even though this sounds somewhat complicated, there’s a rather simple baseline you could follow when it comes to impedance. Before we get into it, however, we would always recommend that you get an amplifier if you want to make the most out of the headphones.
When you’re looking at headphones with an impedance of up to 32 Ω, you’re generally okay without an amplifier.
Whether you’re using them on your computer or laptop, or even with your smartphone, you should be able to get to a decent volume level without any issue. When you’re somewhere between 33 and 100 Ω, you could maybe do with a computer that has a good audio section, or a smartphone with a powerful amp.
However, it’s still a good choice to get an amp, even something that’s compact and portable, and doesn’t cost too much. And then come the big boys – anything above 100 Ω will certainly require an amplifier.
Most modern headphones, whether it’s something entry-level like Beyerdynamic’s DT770 250ohm or something higher end like Sennheiser’s HD650, will require an amplifier. And when you get one, you will instantly hear the difference.
How does impedance affect sound?
We can’t blame you for wondering, at this point, why would you get a pair with higher impedance? Just get headphones that you can drive from your smartphone, right?
Well, not really. Higher impedance means that the headphones have a better ability to handle electrical signals. In audio terminology, that means the sound reproduction will be more accurate and vivid.
That’s not to say that a low impedance pair of headphones is bad, but if you’re going for a premium pair, get a high impedance pair and a suitable amp for them.
What about Headphone Sensitivity?
Even though related to impedance, sensitivity isn’t all that important when it comes to buying a pair of headphones. Sensitivity is all about how loud a pair of headphones is at a certain power level.
If you have two pairs of headphones with a different sensitivity level at the same power level, the one with higher sensitivity will be louder at that power level. The higher the sensitivity, the less you’ll need to turn the volume up in order to get more volume.
When you’re shopping for headphones, you’ll find that anything below 86dB is considered to be fairly low, while anything above 110dB is moving towards the high end. You won’t always find this listed as sensitivity, however.
Some manufacturers refer to it as efficiency or even sound pressure level (SPL). This is because sound works by making waves in the air. The higher the volume, the higher the pressure. But don’t go too far, as very high pressures can actually hurt.
Now, why isn’t this too useful when shopping for headphones? Well, because manufacturers tend to be somewhat inconsistent with how they measure it.
For example, Beyerdynamic might take different measurements to Audeze (or not, this is merely a wild guess). And when you add to this just how many amplifiers and DACs and sound sources there are, as well as the hearing abilities of the person using the headphones, and there are just too many variables for sensitivity to be an important factor.
There is one area where sensitivity is important, however. When you’re looking at sensitivity, it’s not just the music that’s going to be loud, but also everything else in the signal chain.
We’re talking about any potential interference or hiss that comes from the amplifier, any electrical noise, everything. This is why, when you’re using a higher-end pair of headphones, with higher sensitivity, you want a high-quality amp that won’t have any excess noise the headphones might pick up.
With all this being said and done, it’s still worth mentioning how you could make use of this all. When you’re shopping for your next pair of headphones, you’ll want to consider what you’ll use to run them as an audio source, and whether or not you have an amplifier and a DAC to go alongside that.
If you’re on a strict budget, and you can’t really afford to spend more money on additional equipment, your best bet is to get a pair of low impedance headphones.
You will be able to run them with your smartphone or a computer, and if you get a pair with decent sensitivity, they’ll get fairly loud, too.
On the other hand, if your budget allows it, by all means, grab a pair of higher impedance headphones, but make sure you get a suitable DAC and amplifier for them, too.
Not only is the amp required to run them well, but paired with a DAC, you’ll make the most of them rather easily. At the end of the day, it’s all about how much quality you want, and how much you’re willing to pay for it.
It’s a personal choice, really, but one that can make a massive difference in your audio listening experience. In most scenarios, you can just plug in your headphones into an audio source, and they’ll probably play your music.
However, with higher-end headphones, you want to make the most of them. You probably spent a fair amount of money on them, and you want to enjoy them the way the manufacturer intended, right?