Headphone impedance is their input impedance. Many technical and operational characteristics depend on it.
If the impedance in the headphones is low (25 ohms or less), then they require less energy to provide high-quality sound. These headphones are well suited for use with devices such as music players, mobile phones, and other portable devices.
And if the impedance of the headphones is more than 25 ohms, then they require more energy for a high level of sound. Such resistance protects them from possible damage caused by overloads. These headphones can be used with a wide range of audio devices. For example, these include models used for dj-ing, whose nominal resistance is about 25-70 Ohms.
If the impedance of the headphones is low, they become more susceptible to damage when using more powerful amplifiers. If you, for example, connect low-impedance headphones to a DJ setup and use it at full power, you will probably blow them up.
So what is the optimal impedance? Headphones that will be used to listen to audio from a portable player or laptop should ideally have a resistance of about 16-20 ohms and a sensitivity of at least 100 dB / mW. If your device meets European standards for maximum volume, it is best to choose headphones with a resistance of 16 ohms, since in such devices the maximum power is even less than in the others.
As a rule, the recommended nominal headphone impedance is indicated in the device documentation.
It is important to consider the impedance of the headphones, as all models have to work with different volumes of electrical energy and resistances. Each headphone model is specifically calculated and calibrated to match specific load volumes. This not only ensures the safety of the use of equipment, but also extends its life span.
Earlier, in the years 60-80, high impedance of headphones was often used, since the output energy of the devices of that time was extremely high. After that, resistors lowering the output voltage began to be used. In 1996, a standard for headphone impedance of 120 ohms was set. This had a significant impact on the production and development of high impedance models, but at the same time hindered further development in other areas. In 2009, the mass sale of iPods began, as a result of which low-resistance equipment gained high popularity. Therefore, the development of low impedance headphones has received a new impetus.
So, impedance is one of, if not the most, but still important characteristics of the headphones. The model you select should match the audio technology you use to achieve maximum sound quality and ensure stable normal operation. Therefore, you should pay attention to the impedance when buying headphones and choose the most suitable model in order to avoid rapid wear and deterioration of the quality of work.