What is Impedance?
By Oxford definition
By Oxford definition: “Impedance is the effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance. “To simplify by application, impedance (effective resistance) exists in both the audio source (often referred to as output impedance) and the speakers/headphones to you listening with (often referred to as load impedance). Impedance is measured in ohms, and depending on the “resistance” level of your headphones, you may or may not need more power from your audio source. The question you can ask yourself when considering impedance is “what is the best match I can make to compliment my headphones to my audio source.
For now, let’s focus on load impedance for headphones. Headphones with low impedance usually do not require high power output from its audio source to produce audio at high levels. This is because the electrical current isn’t being resisted as much. Most cell phones are good examples of sources that would be more suitable for low impedance headphones. It is important to note that overloading low impedance headphones with a high power source or amplifier will more than likely result in a blown speaker. Low impedance headphones are generally estimated at 25 ohms or below.
A new standard
On the other end, headphones with high impedance have more electrical resistance. This means that you will naturally need more power output from your audio source to allow these high impedance headphones to achieve their optimal sound and volume. This boost of power usually makes for a wider representation of audio frequencies as well as more impactful dynamic range. There is a large variety of different headphone amplifiers and portable audio players that have higher electrical output, but as mentioned earlier, impedance also occurs in the audio source. High impedance headphones are usually estimated at 25 ohms and above. In regards to Moore’s law, technology is simply getting better and better. In 2019, headphones with an average load impedance of 32 ohms are becoming the new audio standard for a high-quality sound that doesn’t cost a fortune or requires an expensive headphone amplifier.
Most smartphones are suitable for powering these headphones, which means the sound quality and musical experience we have will get better and better in time. Our new AU Stream ANC headphones meet this new 32-ohm standard and sound great with standard smartphones, and since they aren’t considered low impedance (<25 ohms), you can generally power these a bit more, resulting in a richer and louder sound. Impedance matching doesn’t simply mean matching impedance numbers of your audio source and headphone. Finding the most appropriate match depends on more factors including the power of your amplifier or audio source, your headphones “load impedance”, your “output impedance”, and your headphone sensitivity (a whole different but relevant topic). There is a lot more to cover in regards to impedance, so stay tuned for future articles where we cover impedance matching, headphone sensitivity, and much more that will empower you to make the best decision on your next pair of headphones.