What is low impedance and high impedance

What does impedance mean?

The Impedance in ohms stands for the resistance of the headphones and states how easily headphones can be driven by an amplifier. Conclusions about the volume can only be made at a given (amplifier) ​​power and taking into account the sensitivity of the headphones pull. Headphones with low impedance (e.g. 32 ohms) therefore achieve the same volume with less voltage than headphones with high impedance (e.g. 600 ohms).

An example:

We connect two headphones with different impedances to a tablet via a mini jack. This tablet can (fictitiously) deliver a level of 1 volt.

  • Headphones I have an impedance of 32 ohms.
  • Headphone II has an impedance of 600 ohms.

We calculate the performance:

  • Headphone I:
  • Headphones II:

The advantage of high-impedance headphones is better resolution and better sound, but headphones with low impedances of approx. 16 to 80 ohms are recommended for mobile use (with smartphones, MP3 players, laptops).

Why is that? Batteries and rechargeable batteries in these devices only supply very little voltage and thus limit the maximum output voltage at the headphone output. This means that low-impedance headphones (such as those included in the Apple iPhone or Samsung Galaxy) are louder than high-impedance headphones when they are used on the same mobile device.

On the other hand, if you only want to listen to music at home in the living room with your hi-fi system (amplifier) ​​or if you use the headphones in the studio, then you should buy high-impedance headphones. The amplifier can and may then output a higher maximum voltage and can "operate" the headphones with higher resolution than a low-resistance one.

Headphones with higher resistances can also be connected in parallel to the same headphone output using a Y-split cable - when using headphones with little resistance, you run the risk of exceeding their capacity when the amplifier is turned up, which can lead to damage (see ohmic Resistances in parallel circuits and Ohm's law).