Headphone impedance explained

If you’re in the market for a new set of headphones, then you’ll quickly discover the selection is enormous. Which set you choose is ultimately down to your own personal preference, but what’s the best way to make an informed decision? As well as all your personal preferences, there is another factor to take into consideration: headphone impedance! What is it, and what’s the right amount for your needs? In this blog post, we’ll be going into depth about headphone impedance so you can make the right choice.

Headphone impedance explained

What is impedance?

Impedance is electrical resistance that is expressed in units of ohms. A set of headphones with a specific impedance demands a certain output capacity from the amplifier it’s connected to. The amplifier has to process that output capacity to ensure that the headphones deliver an optimal sound. This means that the output impedance of the headphone amplifier needs to correspond with the impedance level of the headphones. It’s generally a good ideal to make sure the headphone impedance is at least eight times more than the amplifier’s output impedance. For example, if the headphone impedance is 16 ohms, then a 2-ohm amp will work perfectly. This ratio is also known as damping factor. (Headphone impedance divided by amplifier output impedance). If the difference is more than eight, then you probably won’t hear it, but if it’s less than eight, then the headphones will not sound as good. The headphone resistance level determines the output voltage an amp requires in order to generate one milliwatt of output power.

Which impedance best suits my situation?

As mentioned above, the higher the headphone impedance, the more output your device’s amplifier needs to generate. Low-ohm (16 – 50 ohms) headphones are better suited to battery-powered devices such as tablets, smartphones or MP3 players. If the impedance is too high, then the volume level of your device will probably be too low. If you need headphones for your Hi-Fi set or for use in the studio, then you’re better off investing in a set with a high impedance level.

A few rules of thumb:

mobile applications: 16 – 50 ohms
studio and Hi-Fi use: 60 ohms or more
DJ: 60 ohms or more
in-ear monitoring: 16 – 50 ohms

Beyerdynamic DT 770 PRO

A great example of a set of headphones that’s availbale in various impedances is the Beyerdynamic DT 770 Pro. These headphones are very popular due to their high audio quality and affordability and they come in three levels of resistance: 32 ohms, 80 ohms and 250 ohms. Beyerdynamic themselves recommend the three different sets of DT 770 Pro headphones for the following uses:

DT 770 PRO, 32 ohms: mobile applications
DT 770 PRO, 80 ohms: for recording in the studio
DT 770 PRO, 250 ohms: for mixing in the studio

‘I already have a set of headphones with high impedance!’

If you already own a set of headphones with a high impedance, then they probably provide an optimal amount of volume when connected to your audio interface or Hi-Fi amplifier, but not when connected to your laptop, tablet or smartphone. One possible solution to this problem is the use of a headphone amplifier, but an even more compact option is a DAC (Digital-to-Analogue Converter), which improves the audio quality as well. Make sure whether a DAC is suitable for your specific device before you invest in one. Bear in mind, these are troubleshooting solutions to be applied as a last resort. For the best results, be sure to invest a set of headphones with an impedance level that best suits your equipment.