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What is Headphone Impedance? High vs. Low, Sensitivity, and More

Last updated: 11 months ago
7 min read

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Headphone impedance measures how much resistance headphones have to electrical voltage. It impacts the sound quality and technical performance.

You’ll also learn:

  • What headphone impedance and sensitivity values mean
  • How to correctly match your headphones with an amplifier
Headphone impedance
CONTENTS (show more)

    What is Headphone Impedance?

    Headphone impedance is the driver’s voice coil resistance to the voltage from the amplifier. The longer the wire that forms a coil, the higher the impedance. We’ll discuss later how that translates to better audio quality.

    In headphone specifications, impedance is listed in ohms or Ω. Headphone impedance can range from 8 to 600 ohms, which is reserved for professional or audiophile products. Those values are measured at 1kHz tone.

    KEY TAKEAWAYS

    • Headphone impedance is the headphones’ resistance to voltage. The higher the impedance, the more voltage an amplifier needs to send to the headphones’ drivers to work correctly.
    • A convenient headphone impedance is around 32 ohms if you match headphones with a portable device or above 100 ohms if you plan to use them in professional applications.
    • There is a source impedance (amp) and load impedance (headphones). For headphones to work correctly, the amp’s impedance must be 8 times lower than the headphone’s impedance.
    • Higher-impedance headphones require more voltage to work properly, so portable, energy-efficient devices can’t run them correctly.
    • Low-impedance headphones require more current to work properly, so portable devices can easily drive them. However, a higher current can lead to more harmonic distortion.
    • Headphone sensitivity reveals how loud (or efficient) headphones are at 1mw or 1V of power.

    What is good headphone impedance?

    A good headphone impedance for devices such as smartphones, laptops, and tablets is around 32 ohms. Headphones with this impedance should play optimally with any portable device.

    USB & Lightning dongles

    On the other hand, higher-impedance headphones theoretically provide better sound quality if you match them with an appropriate headphone amplifier.

    That doesn’t mean portable devices can’t run higher impedance headphones to deafening loudness. However, it does mean they can’t provide optimal technical performance.

    2 types of impedance

    In audio, there are 2 types of impedance: source and load impedance.

    • The source is an amp
    • The load is headphones

    When buying a pair of headphones or an amp, you need to consider both impedance values to maximize the headphones’ efficiency. That’s because some amps are optimized for low and others for high impedance loads.

    Pairing low-impedance headphones to an amp optimized for high impedance loads can result in sub-optimal performance, even distortion.

    High Impedance Headphones

    High-impedance headphones have drivers with higher electrical resistance to voltage, which require stronger amps optimized for high-impedance loads, to power them correctly.

    Headphones with a high impedance load have a thinner wire that forms a voice coil. Because it’s thin, you need it to be longer to create a coil. The result of additional length is extra impedance.

    Sennheiser HD 6xx changing earpads
    Sennheiser HD 6xx have 300 ohms, making them very high-impedance headphones.

    Furthermore, the thinness of the wire ensures it’s more closely tied together, which increases efficiency when creating a magnetic field. It also makes the coil lighter, so the speaker system moves more effortlessly.

    All of this combined results in an overall more controlled technical performance with less driver distortion. Beyerdynamic states that high-impedance headphones reveal slightly more resolution in higher frequencies.

    Note that high impedance doesn’t mean your smartphone can’t run the headphones loudly. However, it can’t run them in a controlled and detailed way. Loudness is determined by sensitivity, but more on that later.

    What headphones are considered high-impedance?

    Any headphones that have more than 50 ohms are considered high impedance. The most famous are the Sennheiser HD 600 series, Beyerdynamic DT, T1 series, and AKG K series.

    Person listening to headphones

    A little bit of history

    In the past, high-impedance headphones (around 100 ohms) were the norm due to high-voltage audio equipment in studios.

    That also meant they were more difficult to burn out in case of a higher voltage burst (accidentally leaving the volume knob on high).

    That said, consumers are slowly shifting towards Bluetooth headphones, leaving wired ones to audiophiles. Consequently, high-impedance headphones are now primarily present in the high-end audiophile market.

    Advantages/disadvantages of using high-impedance headphones:

    • When paired with a suitable amplification, headphones sound more controlled and are less likely to distort.
    • They’re more resistant to sudden power overloads, like in a studio if you accidentally leave the volume gain on a high setting.
    • Hooking multiple high-impedance headphones to one source doesn’t lower the output power (high impedance needs voltage, low impedance needs current, which puts higher stress on the amp), making them a good pick for studio monitor headphones.
    • They’re harder to drive efficiently from a portable device, risking potential distortion and loss of detail.

    Low Impedance Headphones

    Low-impedance headphones have drivers with less voltage-resistant coils. Instead of voltage, they require a higher current.

    We are talking about the coil design, which uses thicker and shorter wires. That creates a weaker magnetic field, with the additional weight affecting the overall technical performance.

    Audio-Technica ATH-M50x wired headphone
    Audio-Technica ATH-M50x are widely used in studio monitoring, and they only have 38 ohms.

    Are low-impedance headphones worse than high-impedance?

    That said, it’s unfair to brand all low-impedance headphones as inferior. There are good low-impedance headphones, like Audio Technica ATH-M70x or Audeze LCD-1.

    A little bit of history

    After the rise of Walkmans and iPods, which required to be battery efficient and consume less voltage, people needed more efficient headphones and earbuds.

    Therefore, 16 to 32 ohms became a standard impedance for consumer-grade headphones.

    Advantages/disadvantages of using low-impedance headphones:

    • They’re easily driven by everyday audio devices at home, like smartphones, computers, AV receivers, etc.
    • Headphones are overall more affordable due to cheaper manufacturing.
    • Due to design, low-impedance headphones are likelier to distort.

    The Difference Between High vs. Low Impedance Headphones

    The main difference is:

    • High-impedance headphones require more voltage and less current
    • Low-impedance headphones require less voltage and more current.
    Portable amp USB

    Taking voltage and current differences from above into account and the overall different driver coil designs, you can better understand why each type is better in various applications.

    • High-impedance headphones generally provide better sound quality (if matched by a proper amplifier).
    • Low-impedance headphones are more universally suitable for any setup you already have.

    Best use cases for each type

    • High-impedance headphones are better used in professional applications like in the studio. Their improved sound control and ability to connect multiple pairs to a single amp make them an excellent choice for studio monitoring or mixing.
    • Lower-impedance headphones can work efficiently even with regular audio devices, making them a more affordable pick for a casual user. The latter also won’t notice the benefits of high-impedance headphones, as modern consumer headphones are already high quality.

    Headphone Sensitivity and Impedance

    Sensitivity value is what you look for when it comes to the actual loudness of the headphones. It’s described with a decibel (dB) value at 1mW or 1V of power.

    Headphones’ sensitivity typically varies between 90 to 105dB at 1 mW of power. The sensitivity changes depending on the frequency and music’s dynamic range.

    Many audio websites and enthusiasts exaggerate that high-impedance headphones sound really quiet with battery-powered devices, which is incorrect.

    You can have headphones with an impedance of 300 ohms but a sensitivity of over 100dB at 1 mW.

    Considering that a standard 3.5mm headphone jack can output around 50mW max power (31.6mW sustained), you can drive the abovementioned headphones pretty loudly.

    So, where’s the catch?

    What is headphone sensitivity (and how it impacts volume)?

    Driving headphones loudly doesn’t mean efficiently. Regardless of the sensitivity value, you must consider impedance to squeeze the best of your headphones.

    As mentioned above, portable devices better deliver current than voltage, which makes them inefficient for high-impedance headphones.

    High or low-impedance headphones, especially if they use dynamic drivers, suffer from impedance spikes at their resonant frequency. Except planar magnetic headphones.

    Dynamic headphone driver

    In practice, the official impedance value can double or even triple at the resonant frequency. This means that to play the frequency efficiently, they need more voltage.

    That’s why you require an amp that can handle all these spikes to drive high-impedance headphones efficiently. However, those amps can be rather expensive.

    How to Choose Headphones with the Right Sensitivity and Impedance

    Generally, headphones with high sensitivity (around 100dB) and low impedance (around 32 ohms) work best with low-powered devices like smartphones, tablets, and laptops. 

    On the other hand, headphones with higher impedance always benefit from a stronger amp, even if they have high sensitivity.

    To give an unpopular opinion, while there are technical benefits of pairing high-impedance headphones to a stronger amp, most casual users won’t hear the difference.

    Even Beyerdynamic admits there are minor sonic improvements.

    What does that mean?

    Unless you are a diehard audiophile willing to spend hundreds of dollars on an amplifier, you should use your hard-earned money elsewhere.

    How to Find an Amplifier that Matches Your Headphones’ Impedance and Sensitivity

    • When buying a new dedicated headphone amp, its output impedance should be 8 times (or at least 2.5 times) lower than headphone’s.

    When you buy expensive headphones, you want them to sound the best they can. However, that involves impedance matching them with an appropriate headphone amplifier.

    The quick answer is to ensure your amp’s impedance is 8 times lower than the headphones’.

    The worst possible combination is an amp optimized for high impedance and headphones with low impedance.

    This results in a variety of problems, such as distortion, damping, and boomy, rolled-off bass.

    • Damping factor occurs when the amp’s output impedance is higher or close to the headphones’ impedance. That results in the amp’s improper handling of the driver, which leads to boomy bass and loss of detail.
    • Increased harmonic distortion occurs when impedance mismatch causes reflections in the audio signal.
    • Boomy, rolled-off bass occurs when the source impedance is only 2 times lower than the load impedance. In that case, the sub-bass region dramatically “rolls off” or becomes inaudible. The rest of the bass response is also audibly uncontrolled and boomy.

    What is a simple solution?

    Make sure that the amp’s output impedance is 8 times (or at least 2.5 times) lower than headphone’s.

    Simply take the headphone’s impedance value and divide it by 8. The amp’s impedance should be lower than the result after dividing.

    Frequently Asked Questions (FAQ)

    Do high-impedance headphones sound better?

    High-impedance headphones sound better, but only when you pair them with the appropriate headphone amplifier optimized for high-impedance loads (higher voltage, lower current). Otherwise, you might encounter distortion, uncontrolled bass, and loss of detail.

    What is good impedance in headphones?

    A good impedance in headphones is between 16-32 ohms when using them with portable devices. But if you own a powerful amp optimized for high-impedance loads, you should pair it with high-impedance headphones (100 ohms and more).

    Which is better, 16 ohm or 32 ohm?

    Headphones with 32 ohms are better because you get some of the advantages of the “higher” impedance, which is lower distortion and more controlled sound. Although, the differences might be negligible.

    Are 32-ohm headphones good?

    32-ohm headphones are good for casual, non-analytical listening using a portable device, where occasional distortion might go unnoticed. Higher-impedance headphones are better suited for more professional applications.

    Conclusion

    To summarize the key findings, what you have to remember is to:

    • Never pair low output impedance load to high impedance source
    • Ensure the amp’s output impedance is 8-times lower than your headphone impedance

    The more you try to learn about audio and headphones, the more complicated it gets. Many things can theoretically affect the sound from its source to your ears, and it’s simply overwhelming.

    However, while you can measure differences in many cases, they aren’t audible. In this instance, it’s okay to oversimplify and only follow a few basic rules to avoid major complications. 

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