Impedance is essential when picking headphones, yet many ignore this all-important characteristic. But audiophiles know better — impedance determines what devices you can use your headphones with, how loud your headphones can get, and so much more.
Headphone impedance affects sound quality. Impedance is based on Ohm’s law, which determines the voltage that powers your headphones. You should use high impedance headphones with an output device that sends a powerful enough signal. Otherwise, the headphones won’t sound good or get loud enough.
Headphone impedance is quite a technical topic. Since it’s a critical factor in the performance of your headphones, this article will attempt to explain it in the simplest terms possible.
What Is Headphone Impedance?
When deciding which headphones to buy, it’s vital to understand how the specifications affect your experience. In the case of impedance, the experience is related to how the headphones fit your device.
Headphone impedance is a measurement of resistance to an electric signal, and it’s usually expressed in ohms. The higher the impedance rating of a pair of headphones, the more voltage it needs to achieve audible sound levels.
How Does Impedance Affects Sound Quality?
Think about the relationship between a car, its speed/acceleration, and combustion. The faster the vehicle is designed to go, the more powerful the engine. As a result, a car’s engine could have a V6, V8, or V12 engine. High-performance vehicles need V12 machines, while regular cars can do well with a V6 or V8 engine.
The same principle works for headphone impedance — high impedance headphones need a more powerful signal from the amplifier. The end result is better sound quality.
How Ohm’s Law Applies to Headphones
Headphone impedance impacts sound quality because of a principle in physics — Ohm’s law. In a nutshell, Ohm’s law describes the relationship between voltage and resistance. Namely, voltage is equal to current x resistance.
However, Ohm’s law is more related to DC current, not AC current that flows through your headphones. That’s why we talk about headphone impedance, not resistance.
When explaining Ohm’s law, we have to explore three key concepts that determine the distribution of electricity and affects the devices that it powers:
- Voltage refers to the possible amount of power that an electrical device can distribute. Voltage is the force that pushes and generates electricity. View this as a body of water.
- Current refers to the flow of that electricity. Visualize the body of water we spoke about earlier. How does it flow? Is the flow powerful, or is it slow?
- Resistance is the force that regulates the flow of electricity. If the current moves too fast and there’s too much electricity going to your headphones, they might explode. Resistance is the force that slows things down just enough for the device to receive enough electricity at a time. The force your headphones apply to slow the current down is called resistance.
Here’s a YouTube video that explains headphone impedance:
The Difference Between High and Low Impedance
Inside headphones are wound copper wires we call voice coils. The thinner the wire, the higher the impedance and vice versa.
Thinner wires make it more difficult for electricity to flow, hence the high impedance. On the other hand, thicker wires allow more current to flow. That’s why thicker wires are seen in consumer-grade headphones, while thinner wires are found in their professional-grade counterparts.
Thinner cables are used in high-end headphones because they allow the headphones to get significantly less moving mass, resulting in significantly better accuracy.
Thicker wires are used in cheap headphones because they don’t require precision engineering and delicate care during assembly. They’re cheaper to make and don’t snap or bend as easily.
To reiterate, you’ll notice that simple consumer-grade headphones typically have an impedance rating of 16–32 ohms.
On the other hand, it’s common to see professional-grade headphones with an impedance rating of over 250 ohms. These headphones require a potent headphone amp to operate.
Low Impedance Headphones
If you have low impedance headphones, you can use them with low-powered devices such as smartphones and laptops.
Low impedance headphones may work with high-powered amps and other audio gear used in studios, but with a caveat. If you use a low impedance headphone with a high-powered amplifier, you risk overloading the headphones.
If you’re going to use low-impedance headphones with a high power output device, make sure you turn the volume way down. Otherwise, the volume could reach the threshold of pain and permanently damage your hearing.
Low impedance headphones are best used for simple music listening on the go. It works perfectly with the power generated from phones, laptops, tablets, and other small devices.
A great option is the Sennheiser HD350BT (available on Amazon.com).
The value is terrific — they have a foldable headband, 30 hours battery life, and a virtual assistant button.
High Impedance Headphones
High impedance headphones are primarily for studio use.
If you were to plug high impedance headphones (250 ohms) into your phone or laptop, you’d get a flat, thin sound. Why? Because the power generated from your computer isn’t strong enough to push past the high resistance.
It doesn’t mean the headphones are bad, just that the output device doesn’t have enough power.
Using high impedance headphones the way they were intended provides the best result.
We need to understand that some low impedance headphones have better sound quality than their high impedance counterparts. That’s because impedance is primarily about the movement of electricity rather than sound quality.
If you’re in the market for high impedance headphones, the Beyerdynamic DT990 Pro Headphones (available on Amazon.com) are a great option.
This beast of a headphone is used for mixing and mastering, thanks to their ability to filter sound effectively. Made in Germany, these headphones are tough, well-built, and durable. A bargain at such a small price.
Now, you may not have a high impedance output device. Maybe you’re a music producer who works with a simple laptop. You’ll need an amplifier.
Find a great headphone amplifier in our guide “14 Best Headphone Amps Under $200 (Buyer’s Guide)“.
Medium Impedance Headphones
Medium impedance headphones are typically between 32–100 ohms and can be used with a variety of audio output devices, from mobile phones to studio mixers.
The versatility of headphones in this range provides a good balance between regular and professional use. Hence, DJs, music producers, and even gamers use them.
With these types of headphones, you may also want to take sensitivity into consideration.
Sensitivity refers to how much power the device needs to get a loud, audible signal. For example, you could have two pairs of headphones at max volume, but one is louder than the other. The difference is that some headphones have lower sensitivity (anything under 100 decibels) and thus need a more powerful signal coming from an amplifier.
The Sony MDR706 (Amazon.com) is a professional pair of headphones in the medium impedance family.
They strike a perfect balance between casual music listening and professional use.
You now know how headphone impedance can impact your music listening experience. The money you spend on headphones doesn’t mean much if you use them with the wrong output device. Make sure you do your research first to avoid wasting money.