There are things to know that will make your listening experience better. One of these is the headphone impedance and sensitivity of audio headphones.
While this isn’t something necessarily listed on websites by manufacturers and isn’t something people usually discuss in casual conversation, learning about it could make a real difference to your audio experience.
Headphone impedance definition
Impedance is a technical measurement. Without equations and scientific jargon, it isn’t easy to understand. It will be simplified and broken down into a pair of headphones delivering high audio and low audio.
Essentially, headphone impedance is how well your headphones can resist an electrical current.
- Most headphones with low impedance (impedance less than 25 ohms) can produce high audio with little power. For example, it will work well when used with devices with weak amplifiers, such as portable devices and portable music players.
Lowers are more vulnerable to blowouts when they’re connected to more powerful amplifiers. You can connect, for example, a pair of headphones lower-priced with low Impedance (18 ohms) and a DJ mixer to blow them out.
- Headphones with higher impedance (25 ohms headphones or more) require greater power to produce high levels of audio. They are therefore protected against damage from overloading. They can be used with a greater range of audio equipment.
You should research the equipment you will be using with the headphones if they are very high in Impedance (e.g., the 250 ohms).
- The range of DJ headphones is generally between 25 and 70 ohms.
There are many terms you need to know when describing Impedance. If the Impedance is viewed as an electronic circuit, it may be called output impedance, while the Impedance for the headphones can be called load impedance.
A key factor is also the source output impedance. The load on the transistors or tubes and the current (or bias) are also important. Because the output impedance of amplifiers is not zero, they will deliver more voltage to higher impedance loads.
Headphone impedance can be rated from 8 to 600 ohms. A standard of 32 ohms is becoming more common. The audio source impedance is usually very low. It can be less than 4 ohms or even close to 0 in some cases. But it can reach 120 ohms for tube amplifiers that are output transformer-less (OTL).
Read More: How To Measure Headphone Decibels?
Low impedance vs High impedance
There is no standard threshold for determining if headphones are low-impedance. Some would argue that 32 ohms or lower are sufficient, while others claim that 50 Ω is enough.
- Low impedance headphones can be used with all headphone jacks. These headphones can be used with portable devices, laptops, and other consumer electronics. They can also be used with professional gear like mixing consoles or recording devices.
- A low-impedance pair could be connected to a high-powered amplifier. Too much signal voltage could cause distortion and even a complete meltdown of the driver diaphragm.
- Low-impedance planar magnetic headphones are more common. Higher impedances are common for moving-coil dynamic microphones that use larger gauge coils.
High-impedance headphones require higher voltages to drive their drivers, but they often have better clarity and performance when matched to compatible amps.
- High impedance headphones can be defined as headphones that have an impedance rating of 100 Ω or more. However, this threshold is not fixed.
- These same headphones tend to suffer when plugged into a typical headphone jack (like those found in consumer electronics) since the internal digital-to-analog audio converters/amplifiers cannot provide the signal voltage necessary to drive the drivers at their full potential.
- Higher impedance moving coils will sound better if they have a lower mass, have thinner gauges, and have more turns. When a current is applied, the coil will fit tighter and produce a stronger electromagnetic field. This improves the audio quality and the driver’s ability to induce electromagnetic energy.
- For their capacitor-like drivers, electrostatic headphones require a very high impedance to work properly.
Note: Headphones with impedance ratings of 32 to 100 ohms are in a grey zone and should sound good with or without an amplifier.
The headphones and source must be paired well to ensure high-quality audio. As you can see from the examples of impedance ranges, a match does not mean both the same, but rather they are complementary.
Below, we will discuss the rules for finding the perfect match. It is sufficient to know that the audio source and headphones’ impedances must not be equal. Also, different impedances require different sources.
Equal source and load Impedance increases the power that can be transferred between headphones and amp, but it reduces frequency bandwidth. This is not what we want for high fidelity.
- Low impedance headphones, which we will define as below 50 ohms, are made to work with mobile devices. They can reproduce sufficient sound quality and volume using low voltage devices.
- High impedance headphones (50 Ohms headphones or more) require strong amplification to work well.
Why Can Some Headphones Rule Low impedance while others rule high?
Low Impedance is one of the main reasons why popular headphone models are so popular today.
Today’s people listen to music, podcasts, and audiobooks on their smartphones. It’s easier to access, more readily available, and much more convenient than carrying around an iPod. The market demands low-impedance and works well, so manufacturers of headphones have been producing them.
These devices have better sound quality paired with lower impedance options, but audiophiles are beginning to feel a bit left behind.
High-end headphones with high Impedance are the majority, and they come at a high price! It’s harder for people to buy that type of product because they have to match the Impedance of headphones with smartphones.
The impedance and sensitivity of audio headphones
Sensitivity of earphones and headphones
Both speakers and headphones manufacturers indicate the sensitivity ratings of their products at 1 kHz (midrange), for 1 mW (milliWatt). Speaker impedance is 1 watt. Very few headphones can handle this much power.
The headphones’ transducers are close to the ears of the listener, ensuring a high level of sensitivity and a few hundredths milliwatts of power. The microphone is placed very close to the transducers in order to measure their sensitivity. Sensitivity can be measured at 90 to 120 dB.
What volume can we listen to?
The most common range is 60 to 80 dB and, for the bravest among us, up to 90 dB. On average, earphones and headphones have a sensitivity rating of 100 dB, which corresponds to the sound produced by a jackhammer. This means that a milliwatt of power is rarely required.
However, most headphone amplifiers and DAPs deliver between 50 and 200 mW, and even up to 1 W for the most powerful models. Amplifiers and headphones are both to blame for the impedance of your headphones. Two questions arise: When and why do you need such a powerful amplifier?
The output impedance and the inevitable loss of power of headphone amplifiers
Because hi-fi quality is dependent on headphones with low impedances (0.1 to 3.0 ohms), the differences in the output impedance of the amplifier and headphones’ impedance can be significant. 15 dB is lost when the amplifier has 0.1 ohm and headphones have 32 ohms. With headphones of 600 ohms impedance rating, this value is almost 30 dB higher.
How an amplifier’s power output can be determined
The power output of an amplifier is often expressed in milliWatts for a given impedance. However, it can also be expressed in volts. This is where you need to calculate the power supply based on the impedance for the headphones that you are purchasing. This formula is simply divided by the impedance.
What should the amplifier’s power be?
Recall that headphones and earphones have different impedances depending on frequency. 13 mW at 300 Ohms and 1 kHz can be reduced to just 5 mW for certain frequencies.
Add to this the power loss caused by the difference in the output impedance of the amplifier and headphones’ impedance. An amplifier that can supply 100 mW is sufficient if the headphones have a very high sensitivity rating (> 100dB).
Know what is impedance in headphones, choosing the right impedance headset depends on what you’re going to use it for. Hooke Audio had shown the indicators so that you can see that the use of each indicator has its own meaning. Hope this article helps you. If you have any questions about this topic, feel free to comment in the box below.