By looking at them, headphones are simple objects. Plug it into your device, put it on, and play music. However, to get the best sound quality out of your headphones, you’ll need to know more about them. The two main specs to understand with headphones are impedance and sensitivity. From here, you’ll know if your headphones need an amp, how loud they’re likely to go, and whether they sound best matched with your device.
In this post, we have put together everything about headphone impedance and sensitivity to help you understand in the simplest way possible. Enjoy.
Headphone Impedance
Headphone impedance is one of the specifications included with every pair of headphones. Impedance is measured in Ohms, and most headphones are rated between 8 Ohms and 600 Ohms. A standard impedance for most headphones out there is around 32 ohms.
So, what is headphone impedance, and what does it mean?
The impedance value of a headphone tells us how much power a given pair of headphones will need to reach a reasonable listening volume. The value is important because it helps match our headphones to the right source for optimum performance. The higher the impedance rating, the more power a pair of headphones will need.
When an electric audio signal tries to pass through a headphone, it encounters some resistance. The resistance can come from the size and type of headphone driver, components inside the headphone, the cables, and anything about the headphone that can offer some resistance.
Headphone impedance is the electrical resistance headphones offer against the electrical current (Audio signal) passing through them. Every headphone needs amplification to run, and every playback device has an amplifier that generates power.
Most headphones can easily be powered by inbuilt amplifiers in our smartphones, DAPs, laptops, and PCs. These are headphones with a low impedance. However, as the headphone impedance rises, so do the power requirements. This is where impedance matching comes into play.
Headphone Impedance Matching
Impedance matching is a crucial factor to consider when buying headphones. If you’ve faced questions like these below, your headphones need the right amount of power to sound best.
- Can I use these headphones with my smartphone?
- Do I need a headphone amp?
This means the output power by your source needs to match the headphone impedance. It does not have to be equal, but the power of your source needs to be more than 50% of the impedance of the headphones.
You’ll need more juice for high impedance cans, which means getting a headphone amplifier. For example, the Beyerdynamic DT 770 has three variants – 32-ohm, 80-ohm, and 250-ohm. Most smartphones and portable playback devices can power the 32-ohm variant. However, for the 80 and 250-ohm variants, you’ll need to add an amplifier to help deliver more power.
Headphone Sensitivity
The term sensitivity in headphones relates to impedance. However, unlike headphone impedance, the sensitivity of a headphone is not very helpful when shopping for headphones.
Headphone sensitivity measures how effectively a headphone driver converts an electrical signal to an audio signal. Different headphone manufacturers use different ways of indicating the sensitivity of headphones:
- dB/V: Sensitivity – This is the decibel Sound Pressure Level at 1-volt root-mean-square
- dB/mW: Efficiency – This is a decibel Sound Pressure Level at one milliwatt
Headphone Sensitivity – Higher or Lower
When using our headphones, we often use 60 and 80 dB to listen to them. Using your headphones at a higher sensitivity, say 100 dB, can cause harm to our ears.
However, most headphones have a rated sensitivity of 100dB or more. When a pair of headphones has high sensitivity, the driver performs better without much power. However, this can also cause audio distortions or damage the headphone driver when used at very high volumes.
Low-sensitivity headphones require more power to reach audible volume levels. This is why a headphone like the HiFiMAN HE 500, despite the low impedance, will need a headphone amp to sound best. However, the headphone driver is hardly damaged even with an amplifier because of its low sensitivity. This makes low-sensitive headphones very durable compared to lo high sensitivity headphones.
Relationship Between Impedance And Sensitivity
Headphone impedance and sensitivity are often used together because they deal with audio signal strength. Impedance tells us how much power you need to reach a reasonable listening volume. At the same time, sensitivity has to do with the audio signal strength required for a headphone driver to reproduce sound at a given volume.
Depending on the impedance and sensitivity specifications, you can apply the following when deciding whether your headphones need more power:
- 32 Ohm and 99dB/mW or more – Your headphones don’t need a headphone amp. They can be easily powered by your smartphone, tablet, laptop, etc.
- 32-80 Ohm and 96dB/mW or more – You can use a good quality PC, laptop, or portable media player. Low-quality playback devices will struggle to reach audible listening volumes, especially with quiet songs.
- 32-80 Ohm and less than 96dB/mW – You should invest in a headphone amplifier
- 80-300+ Ohm and less than 99dB/mW – You should get the best headphone amplifier
Wrapping Up
I hope I’ve explained enough to help you know headphone impedance and sensitivity. If you have any questions, feel free to comment below, and I’ll answer. If you need to know more about terms like total harmonic distortion, frequency response, and more, check out this informative headphone specs guide we’ve put together.
