When buying a pair of headphones, most people typically consider factors, such as sound quality, comfort, durability, and so on. However, they often overlook an important factor: headphone impedance.
Whether you’re an audiophile or music producer, you must understand headphone impedance and make note of it to buy the right headphones per your requirement.
What Is Headphone Impedance and Why Is It Important?
Headphone impedance is the measure of a pair of headphones’ resistance to electric current (audio signals) passing through it. Or, in other words, it’s the measure of how much resistance an audio source may have to overcome to present its audio signals to your headphones.
Headphone impedance is measured in Ohms and can greatly affect the sound quality and volume of your headphones. It measures how much power your headphones require to be driven to their full potential.
Headphones with higher impedance require more power to produce the same volumes as headphones with low impedance. Therefore, they don’t sound very loud with audio sources, such as smartphones.
What Is Impedance Matching?
Impedance matching simply means that the output impedance of an audio source should be compatible with your headphones’ impedance for best sound performance. It does not necessarily mean that both impedances should be matching.
Some audio sources and amplifiers comprise a setting or switch that allow you to select the appropriate impedance for your headphones.
Here are three different scenarios depicting the relationship between headphone impedance, audio source output impedance and sound quality.
1. Output Impedance of Audio Device > Headphone Impedance
2. Output Impedance of Audio Device < Headphone Impedance
3. Output Impedance of Audio Device ~ Headphone Impedance
What Is Headphone Sensitivity?
Headphone sensitivity measures how loud a pair of headphones can sound or how efficiently a pair of headphones can convert electrical signals into sound. It is measured in decibels per milliwatt (dB/mW).
Headphones with higher sensitivity rating can reach higher volume levels even with low power input.
Are Headphone Sensitivity and Impedance Related?
Headphone sensitivity and impedance are not directly related. However, they both are important factors that can determine the loudness and sound quality of a pair of headphones.
Again, let’s look at an example for better understanding.
For example, if you have an amplifier with 16-Ohm output impedance, you’ll need headphones with 16-Ohm impedance for optimal sound performance. The impedance and sensitivity of the headphones will determine how they will sound.
Now, if you have an amplifier with 16-Ohm output impedance and headphones with 32-Ohm impedance and same sensitivity as the above-mentioned 16-Ohm headphones, they will sound quieter.
However, if the 32-Ohm headphones had better sensitivity, they would have sounded louder even with low input power.
What Is the Relation Between Headphone Impedance and Power Output?
The higher the impedance of a pair of headphones, the higher will be the power required to drive them.
When an audio source, such as a smartphone or tablet, is connected to a pair of headphones, the audio source’s amplifier should provide enough power required to drive the headphones to the desired volume levels.
The relationship between headphone impedance and power output is based on Ohm’s Law, which says that current flowing through a material is directly proportional to the voltage across the material.
How Does Headphone Impedance Affect Sound Quality?
Headphone impedance can affect sound quality in three ways:
- Frequency response
How Does Headphone Impedance Affect the Volume of Headphones?
The headphone driver in high-impedance headphones requires more power to play at higher volumes. Therefore, they are typically quieter and do not sound loud with audio sources that have low power output, such as smartphones and tablets.
On the other hand, low-impedance headphones can easily achieve high volumes even with devices that have low power output.
How Does Headphone Impedance Affect the Frequency Response of Headphones?
High-impedance headphones come with a flat frequency response as they’re not affected by the output impedance of the audio source. Therefore, they can produce more precise and detailed sound across different frequency ranges. Some of the best mixing and mastering headphones come with high impedance.
On the other hand, low-impedance headphones can deliver bass-heavy or brighter sound as their frequency is easily affected by the output impedance of the audio source.
How Does Headphone Impedance Affect Sound Distortion?
If the power delivered by an audio source does not match the power a pair of headphones can handle, the result is sound distortion.
Since high-impedance headphones require more power to produce the same volume as low-impedance headphones, they are less likely to produce sound distortion.
On the other hand, low impedance headphones require less power to be driven to their full potential. Therefore, if they receive more power from an audio source than they can handle, they can produce sound distortion.
High-Impedance vs. Low Impedance Headphones
Here’s a quick comparison between high-impedance and low-impedance headphones:
|Power Requirements||Require more power to be driven; therefore, are not suitable with devices that have low output impedance||Can be easily driven by devices that have low output impedance|
|Headphone Amplifier||May require an amplifier to drive them to their full power||Do not require amplifier|
|Audio Quality||Deliver more accurate and detailed sound, with better overall dynamics and separation||May not produce detailed sound; suitable for casual listening and daily use|
|Durability||More durable; do not get internally damaged easily||May get damaged when using with devices that have high output impedance|
|Portability||Less portable as they may require an external amplifier||More portable|
How to Choose the Right Impedance for Your Headphones?
Ideally, headphones with impedance between 20 to 40 Ohms are suitable for casual listening. However, your headphones’ impedance will primarily depend on your usage.
To pick the right impedance for your headphones, you must determine how you plan to use the headphones.
|Usage||Low/Med/High Impedance||Suitable Impedance Range (in Ohms)|
|Portable Device||Low||16 to 32|
|Gaming||Per system requirements||16 to 32 (portable devices)|
250 to 600 (PC with sound card)
|Home audio systems||High||>80|
How to Measure Headphone Impedance?
You can measure headphone impedance using an electronic device called an impedance meter. An impedance meter applies alternating current across your headphones and measure the voltage generated to build resistance.
Some audio equipment, such as audio interfaces or headphone amplifiers, also have built-in impedance meters that can measure the impedance of your headphones.
You can also check the impedance of any pair of headphones on their specifications sheet.
In conclusion, headphone impedance is an important factor to consider when buying headphones and other audio equipment.
Low impedance headphones work well with portable devices and smartphones and are easier to drive. High impedance headphones typically require more power and produce best results with dedicated headphone amplifiers.