What is Impedance in Headphones?
- 21 Nov, 2018
Specifications on impedance are among the crucial things that most headphone buyers ignore. Ignoring this might not lead to something catastrophic but may limit the quality of sound from the headphone of your purchase. You may end up purchasing one with an impedance that is too high or very low for your music player or amplifier.
Many people often ignore this feature, not because they don’t know about it, but because they don’t understand impedance on headphones. Well, the article below focuses on demystifying what is impedance in headphones and related terminologies for audiophiles. This will guide them in making better headphones purchase decisions.
What is impedance?
Impedance is a technical measurement that cannot be explained without equations and scientific justifications. However, we will try to simplify and break it down for audiophiles to understand the difference between high and low impedance.
To begin with, when you hear of impedance, think about the electrical resistance - R from physics measured in Ohms. Take the example of a simple circuit with the basics, a battery and a resistor. While the battery generates voltage that forces current around the circuit, the resistor resists the current. The higher the value of the resistor, the lower the current passed and vice versa.
In the process of resisting the current, some voltage difference is developed. This phenomenon is what is referred to as the Ohms law. In the law, voltage is abbreviated as V equals the current passed, I multiplied by the resistance of the resistor, R. This is where the common physics expression V = IR was derived from.
From this algebraic arrangement, if a battery has a voltage of 12V and the resistor has a resistance of 120 Ohms, the current flowing will definitely be 0. 1A. This is a simple example of a circuit with direct current, where the battery voltage is unchanging and steady.
However, when dealing with electronics, the signal voltage changes continuously due to the change in the amplitude of the audio signal as it alternates between the positive and negative cycles. Currents flowing, therefore, have varying amplitudes and alternate in direction, generically known as alternating current circuit.
This is what complicates everything. Besides the resistance, there are other fundamental components that affect the current flowing through this alternating current circuit. Apart from the resistance already mentioned above, there is the capacitance and inductance. These act like resistors only that they resist current changes in proportion to the frequency of signal voltage fluctuations.
All audio electronic devices have a combination of capacitors, resistance and inductors in the same circuit. Other components of the circuit include valves and transistors that provide amplification or act as switches. The total resistance of an audio electrical device includes those developed by resistors, capacitors and inductors. This whole lump is what is referred to as the impedance. Impedance, symbolized as Z is measured in Ohms.
What is headphone impedance?
As mentioned before, impedance is generally overall resistance within the circuit. How does this affect headphones? You may ask. well, headphones have driver units within the speakers that provide the audio output. The speakers have magnets that help in generating sounds in the headphone.
The magnets require current to operate. Where there is current, from our previous explanation, there is impedance. This is because this circuit with drivers and magnets require current to function. For the circuit to be functional, the overall resistance determines the current required to overcome impedance and generate enough electricity to power the speakers. This is what distinguishes between high and low impedance headphones.
What is the effect of impedance on headphones?
The effects of impedance on headphones cannot be ignored. For starters, it determines the current required to pass the audio signal across the circuit. That said, headphones with low impedance, say less than 25 ohms, require little power to deliver high-quality audio signals. This is perhaps the reason why such headphones work well with equipment with weak amplification such as phones and portable music players.
On the other hand, headphones with high impedance, that is 25 ohms and over require more power to deliver high audio levels. High impedance headphones are protected from damages resulting from overloading and can be used with a wide array of audio equipment.
Types of impedance on headphones
There are two types of impedance on headphones. The impedance of any headphone hugely relies on the driver’s voice coil used in manufacture. Headphones can either be of high or low impedance.
As mentioned before, high impedance headphones are less sensitive and require more power to drive. This power requirement comes down to the voice coil of choice used in the headphones drivers coil and small speakers that sit within the earcups. High impedance models are perfectly suited for home use than on the go use.
Low impedance headphones, as mentioned, require less power to deliver high-quality audio. Due to this, they are better suited for both home use and on the go, if you need to connect with a smartphone. This perhaps explains the reason why most in-, on-, and over ear headphones are of low impedance design.
Categories of headphones according to the impedance
Broadly, headphones are categorized into three clusters by their impedance. The clusters include;
- Broadcast – this group consist of high impedance headphones, typically ranging between 1.5 and 2 Ohms. The reason behind this high impedance is to allow the headphones to be plugged to a patch bay and monitor the signal source without loading unduly or causing a drop in level.
- Professional headphones – these headphones have impedance ranging from 150 to 600 Ohms. These models base their functionality on the premise that the lower the impedance, the higher the volume.
- Portable – as the name suggests, these models are designed to be used with portable CD players and similar devices. These headphones have impedance ranging from 8 to 32 ohms.
Best High and Low Impedance Headphones
Having outlined some of the basics describing impedance on headphones, it is best to highlight some of the best high and low impedance headphones on the market.
Sennheiser HD 700 Headphone
The Sennheiser HD 700 Headphone is a large and full-size audiophile headphone model that has a wide-open sound profile and great sounds when used on digital music players. Despite being expensive, these headphones sound overly effortless without any strain, harshness or an aggressive edge.
The headphones have an impedance rating of 150 Ohms, perhaps the reason behind its soft and smooth sound with no exaggerated frequencies. It is a straight choice of headphones for buyers who want headphones that produce quality sound with nothing added or taken away from the music.
Its unique styling may not align with everyone’s taste, but it looks great. Its overall build capacity is top-notch with comfortable microfiber covered earpads for enough air circulation. This reduces the likelihood of sweating compared to leather pads that often make audiophile ears sweat.
The Sennheiser HD 700 Headphone’s earpieces are flexible and can move both lateral and vertical positions. This makes them able to conform to everyone’s head shape without much struggle. Its open back design doesn’t isolate the wearer from hearing background environment noise.
With its impedance rating, you can use this headphone with portable music players and phones.
Beyerdynamic Amiron Wireless Headphones
The Beyerdynamic Amiron Wireless Headphones are the best sounding low-impedance headphones you can get at its price range. It provides a spacious sound that is detailed, perhaps enough to make you rediscover your music library content.
Of worth noting in our review is the low impedance rating of 28 Ohms. Some of the intriguing features of this headphone include the wireless design, excellent build quality, detailed and dynamic sound and comfortable feel.
Beyerdynamic Amiron Wireless Headphones bulky design and averagely rated noise isolation feature makes them a terrible choice for travel. Nonetheless, they are the best pick if you need a low-impedance headphone with quality sound.
How to measure impedance in headphones?
Measuring the impedance in headphones requires that you use some specialized tools. However, if you just want to confirm the general range of your speakers, a multimeter is all you need.
Doing a quick estimate
Perhaps the best way to confirm the impedance rating of headphones is by checking the normal impedance rating on the headphones. Most manufacturers list the impedance ratings on the packaging. Whether 4, 8 or 16 Ohms, this is an estimate of the minimum impedance for standard typical ranges. The actual impedance rating is often close to the value and within this range.
Using a multimeter to measure resistance
A multimeter is a simple machine that sends out small DC currents to measure the resistance of the circuit. Since impedance depends on the quality of the alternating current circuit, this method will not measure impedance directly. Nonetheless, this approach will get close results, especially for several home audio setups. For instance, distinguishing between a 4-ohm and 8-ohm headphones can be done this way.
Which is the best impedance for headphones?
Deciding on the best impedance headphones is purely a personal choice. This hugely relies on how you intend to use the headphones with. If you intend to use them with home equipment, consider getting high impedance models. On the other hand, go for low impedance models if you want something you can juggle between playing at home and on the go electronic devices.
Headphones with low impedance are often susceptible to blow-outs, especially when used with powerful amplifiers. High impedance headphones take advantage of their design that prevents damage caused by overloading.
Some of the commonly asked questions about headphone impedance include;
How do I get the best of high-impedance headphones?
To get the best of high impedance headphones, it is worthy if you consider using a stereo amplifier for listening tests. However, this doesn’t mean that high-impedance headphones plugged in a phone’s output won’t work. However, since headphone jacks are designed with regular impedance headphones in mind, you will not get the best from this setup.
Why do I require headphone amplifiers?
The correlation between headphone loudness and impedance is inversely proportional. That said, the lesser the impedance, the higher the output volume. The notion that headphones with high impedance produce better audio quality isn’t always true.
To explain this speaker drivers with high impedance are made of better materials. This gives a better audio quality when playing similarly high-quality audio files. This top-notch quality helps in maintaining the audio fidelity, making the headphone audio more original.
What determines the impedance of a headphone?
The impedance of any headphone is determined by the driver’s voice coil. For high-impedance models, the voice coil wire is super thin, probably half the thickness of human hair. Thin wires result in more windings on the voice coil compared to lower impedance headphones, which have thicker and heavier wires.
Why aren't all headphones manufactured with high impedance?
As mentioned above, high impedance headphones have thin voice coil drivers, which result in less sound distortion and better level of bass production. Despite being awesome, all headphones can’t be manufactured like this majorly due to manufacturing costs.
The thin voice coils found in high-impedance headphones requires utmost precision to make, thus raising the manufacturing costs. Besides, high impedance headphones require more power, meaning that portable music players running on batteries may not effectively handle the power requirements.
To sum this up, understanding clearly the details of impedance in headphones might certainly be daunting. However, our guide has tried to outline in the best possible way some of the basics when it comes to an understanding of what is impedance in headphones.
High impedance headphones offer the ever-tempting benefit of better numbers. Note that these benefits are subtle and require proper equipment, including voice amplifiers to enjoy its full advantage. Therefore, if you feel that the sound from your mid-range headphones requires some little refinement, go for the high-impedance.
On the other hand, if you don’t mind the lack of clarity in your headphones and willing to settle for average when it comes to sound quality, consider the low impedance headphones. Both types work well, especially when suited to compatible devices and music players.