Impedance in headphones is quite a technical topic, but it dramatically impacts the performance of headphones.
It is measured in ‘ohms,’ and for each headphone, its value differs. But what does this number denote?
Despite its obvious significance, many headphone manufacturers don’t generally highlight it in their spec chart.
In this article, I will dispel this situation by explaining what’s impedance, its impact on sound quality, the concept of impedance matching, and how high and low impedance impact headphones and earphones.
Impedance – What does it mean?
Impedance is one of the basic and perhaps the most critical specifications of headphones and earphones.
It is mentioned on the datasheet of every quality pair of headphones and sound systems.
The impedance of a headphone is conventionally rated between 8 and 600 ohms, with about 32 ohms becoming increasingly common as the standard.
Headphones with impedance in the higher ranges (around 25 ohms and above) demand more power to deliver audible sound levels.
Consequently, they are protected from damage triggered by overloading. Allowing you to use them with a broader range of audio equipment.
Impedance also can affect the sound quality of a playback device like headphones, earphones, and speakers.
Headphone impedance can be understood as the inherent opposition that the headphone circuitry has to the electrical current flow.
When you plug a headphone into an audio source, it creates a closed circuit, causing a stream of electric current to flow.
A headphone’s internal circuitry partially resists the electric current sent from the audio source. This resistance is referred to as impedance.
That is, impedance is the measurable rating of how well headphones and earphones resist electrical current.
Low or High Impedance – Which is better?
In simple terms, high-impedance headphones are known to provide good sound quality. However, you might have to power them with a higher voltage.
This is why 30-ohm headphones are amongst the best choices for phones, 250-ohm headphones are an excellent option for external audio interfaces, and 80-ohm headphones are a good bet for a little of both.
High-impedance versions sound more transparent and clearer, their bass definition is better, and the soundstage is more spacious.
These headphones are geared towards use by professionals or audiophiles because they call for bulky special equipment.
Despite the advantages of high impedance, low impedance equipment is still more suited to casual listening on phones or laptops.
The impedance ranging between 20-40 ohms is considered an appropriate choice for casual music listeners and 64 or above for audiophilia.
Essentially, the headphone driver creates the sound you hear, which has a significant role in impedance numbers.
You can imagine headphone driver units as tiny loudspeakers that stay in, on, or over your ear, depending on the type of headphones or earphones you use.
In general, as the size of the headphone driver increases, its impedance too will be higher.
Mainly there are four types of headphone drivers: dynamic, planar magnetic, electrostatic, and balanced armature.
Although not without their advantages and disadvantages, they can all prove to be extremely high quality.
Dynamic headphone drivers are the most common types and are just the standard cone with a magnet and coil of wire type.
It is common for dynamic drivers to have non-single valued impedance curves. What this means is that their impedance varies depending on frequency.
This can change the frequency response of headphones if an amplifier drives it with a high output impedance.
Planar magnetic use a plane of magnets and wires passing by them to create planar sound waves, which are believed to sound a little more like speakers.
With typically lower impedances and single-valued impedance curves, Planar magnetic drivers are incredibly high quality.
In the case of electrostatics, extremely high voltages are required. Also, they can burn a hole through your pocket.
High-impedance headphones tend to benefit from an amplifier.
Often shortened to a headphone amp, a headphone amplifier is an accessory to increase the audio volume without compromising quality.
Take, for example, a 300-ohm headphone, which is relatively high. It will probably make noise or be unresponsive when plugged into a phone, but you can expect some truly stellar sound when it’s plugged into a headphone amp.
You should note that impedance is not the only indicator of needing an amp.
Impedance matching – Why is it important?
Headphones are fundamentally electronic devices, and so are bound by the laws that apply to electricity.
Impedance matching is the process of proportionally matching impedances between the headphones and the connected device (phone, laptop, amplifier, etc.) to enable maximum power transfer.
The audio source and the headphones should be compatible with each other to achieve high-quality sound output. It is an essential step to ensure maximum efficacy.
You can effectively match the impedance of a headphone by connecting it to a device having an output impedance of less than 1/8th of the headphone’s impedance.
For example, if your headphone is rated 32 ohms, your amp’s output impedance must be less than 4 ohms.
Impedance matching is necessary so that maximum power can be transferred from the amplifier stages to the load. It is also a way to decrease distortions and noise coupling in the amplifier stages.
When impedances are mismatched, it cannot deliver quality output. Furthermore, standing waves would develop along the line. This means that the load does not absorb the total power sent down the line.
When seen as a simple electronic circuit, the audio source’s impedance can be written as output/source impedance, whereas the impedance of the headphones can be deemed as load impedance.
An important factor in a headphone’s output quality is its impedance. And yet, this spec is often left unpublished by many manufacturers.
But manufacturers that release high-quality, pricey headphones proudly show off their impedance values.
An overwhelming majority of people looking to purchase new headphones are not likely to pay much heed, if any, to output impedance.
You should note that even if the headphone jack fits into an amplifier, it doesn’t mean that those two devices will work together smoothly. While nothing might break, the sound can be affected.
A common source of trouble, impedance mismatches often lead to audio soundstages being dramatically increased on some sources and not on others, the bass response being chaotic, and the mids being so muted they are almost impossible to hear.
Impedance mismatch can cause signal reflection and inefficient power transfer. These reflections result in destructive interference, causing peaks and valleys in the voltage.
So, impedance matching is crucial to achieving a desirable voltage standing wave ratio (VSWR).
Making educated decisions when selecting an amplifier for your headphones is essential.
Headphones with low impedance ratings are more prone to “blowouts” when used with powerful amplifiers.
If you were to connect a lower-priced pair of earbuds with low impedance (such as 18 ohms) to a DJ mixer and turn the volume up to the max, you’d most likely blow them out.
Final Thoughts – Does Impendence Matter?
Impedance is one of the basic specifications of every quality pair of headphones and earphones.
It substantially affects your music-listening experience, but not many understand what it does to the device.
While nothing disastrous may happen due to an impedance mismatch, you might miss out on listening to the best sound quality because of an impedance that’s too high or too low for your music player or amplifier.
I hope this article helped you understand how impedance and its matching play a vital role in the performance of headphones.
No matter what headphones you choose, and whatever their purpose, definitely make sure that it has the proper amount of amplification to deal with the headphone’s impedance.
If you have any interest in headphones that you can use with portable (battery-powered) music players or at home with a receiver or integrated amp, choose low-impedance, under 50-ohm headphones.
If it is a strictly stay-at-home headphone, you can opt for high-impedance models.
For casual music listeners, the impedance range between 20 to 40 ohms is considered an appropriate choice. This range increases to 64 ohms or above for an audiophile.
When you know the impedance of a pair of headphones, you’ll be able to make wise decisions about the audio sources best suited to the headphones and gain optimal performance.
If you have any questions for me, please ask them through the comment section below.
Frequently Asked Questions
What does impedance say about your headphones?
Impedance value gives an idea of how much power your headphone needs to provide the best sound quality. The impedance value denotes the resistance it exerts to an incoming electrical current.
Are high-impedance headphones louder?
All other factors remain unchanged; headphones with a lower impedance will be louder than headphones with a higher impedance because a higher impedance demands a higher voltage level from amplifiers to attain the same relative loudness.
Why do high-end headphones have high impedance?
Higher impedance enables more turns of wire to be utilized in the driver’s voice coil. This helps to improve the potential of a headphone’s sound quality. Low impedances are in the range of approximately 4 – 16 ohms. Speakers with low impedance are used in different sound systems, for example, household stereo and car sound systems. High impedance generally translates from several hundred ohms.
Why do high-end headphones have high impedance?
Since impedance is nothing but the opposition to current flow (resistance) by the circuit, it is measured in ohms. A higher value of ohm simply means a higher value of resistance. When the resistance is high, the current flow is more diminutive.