Decoding Headphone Impedance: What You Need to Know

Impedance is a crucial but often overlooked factor when it comes to choosing headphones or earphones. Understanding what impedance is and how it affects your audio experience can help you make informed decisions. So, let’s dive into the world of impedance.

1. Impedance Explained: Impedance, typically measured in ohms (Ω), is a measure of the resistance that electrical signals face as they pass through the headphone’s drivers. It’s like the resistance in a water pipe, affecting the flow of water (in this case, electrical signals). The higher the impedance, the more resistance there is.

2. Headphone Impedance Ranges: Headphones come in various impedance ranges, usually categorized as low, medium, and high impedance. Low impedance headphones typically range from 8Ω to 32Ω, medium impedance headphones range from 32Ω to 100Ω, and high impedance headphones can go beyond 100Ω.

3. Impact on Sound Quality: Impedance has a significant impact on how headphones sound. Lower impedance headphones are easier to drive and are often more efficient. They work well with portable devices like smartphones and don’t require additional amplification. Medium impedance headphones are versatile and can work with a wide range of devices. High impedance headphones are less efficient and might require dedicated headphone amplifiers for optimal performance.

4. Matching Impedance: To get the best audio quality, it’s essential to match headphone impedance with the output impedance of your audio source (e.g., a smartphone, audio interface, or amplifier). Mismatched impedances can lead to poor sound quality, distortion, or inadequate volume.

5. Sound Characteristics: Impedance can influence sound characteristics. Low impedance headphones tend to have a more extended bass response and can sound louder on portable devices. High impedance headphones may provide better clarity and detail but require external amplification.

6. Choosing the Right Impedance: When selecting headphones, consider your usage. For portable devices, lower impedance is practical. Audiophiles and professionals may prefer high impedance headphones paired with dedicated amplifiers for the most refined sound.

7. Impedance and Sensitivity: Impedance should be considered alongside sensitivity, which measures how effectively a headphone converts electrical signals into sound. High sensitivity can compensate for high impedance, creating an efficient and high-quality listening experience.

In summary, impedance plays a significant role in headphone performance. Understanding its impact on sound quality and compatibility with your audio source is vital for selecting the right headphones to suit your needs and preferences.

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:

1. Volume
2. Frequency response
3. Distortion

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:

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.

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.

Final Words

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.