There’s a long-standing debate about whether mains cables affect sound quality. Some users say they’ve seen astonishing results after replacing their regular cord with a relatively expensive Hi-Fi mains cable. Others argue that audio quality has nothing to do with the power cord. Who’s right?
Hi-Fi mains cables only make a slight difference in amp output and noise, but the difference isn’t large enough to cause an audible change in sound quality. Plus, A/B tests don’t confirm the perceived gains some users report, and companies don’t usually publish factual data to justify their claims.
In the rest of this post, we’ll discuss why Hi-Fi cables don’t make much of a difference in quality and explain why some people perceive an improvement with more expensive cables.
Why Hi-Fi Mains Cables Can’t Improve Audio Quality
Power cords mainly serve one purpose: to transfer power from your wall outlet to your amplifiers, audio sources, and other components. They aren’t part of the signal chain. In other words, they don’t transmit audio signals. So, they can’t directly impact your audio signal.
A Hi-Fi cable doesn’t modify your device’s frequency response—the characteristics of the output signal. So, your notes won’t sound more or less powerful or punchy if you change your cord. Besides, the distortion levels stay the same, with no discernable differences in the shape and form of the transient signals.
However, the indirect effect isn’t non-existent; it’s negligible. If your cord has high resistance, your audio source will receive less electrical current, which will reduce the output level. But the difference is only 0.1 dB over 50 feet (15.24 meters) of cable.
A second difference between regular and Hi-Fi cables is in the noise levels—specifically Total Harmonic Distortion plus Noise or THD+N. Normal power cables perform slightly worse in terms of THD+N but only 0.2 dB. To put that into perspective, consider these examples: when you speak at an average level, your voice is around 60 dB loud, and a heavy metal concert can go up to 120 dB. So, a 0.2-dB advantage isn’t that big a deal.
Also, note that the AC cables in your building walls aren’t Hi-Fi. So, the final few feet of cable from your outlet to your component won’t make a huge difference. Many online users with experience in professional recording claim that recording studios don’t spend much on main cables.
Thus, to improve your overall sound quality, you should look for other optimization opportunities.
Why Do People Hear Different Sound Quality?
So far, we’ve established that the mains cable can’t have a significant effect on your audio signal quality. However, many people say they hear different sounds. There are even YouTube videos demonstrating the difference with loads of positive comments. Have a look at this one for example:
Now, how can that be?
There are two main reasons for this phenomenon:
- How the test is conducted
- Our brain’s limitations
Here’s a better look at the role each plays:
When you’re switching between power cords, you see which cord is connected to the device. In scientific terms, you’re not doing a blind test. So, your mind could play tricks on you and make you think the expensive cord is improving sound quality.
To remove this effect, you should have someone else switch the cords without giving you any hints. And it’s better to close your eyes when listening so that you don’t receive any visual cues.
Testing two power cables using the same audio source takes time because you have to turn off the device, replace the cords, turn the device back on, and wait until it warms up. This process can take at least 30 seconds. But our brains can’t retain audio for that long.
The auditory information we receive from our surroundings stays active for only three to four seconds in our heads. What’s more, the brain can only understand basic information about audio (e.g., the loudness), and new information quickly replaces the old. So, your brain can’t possibly remember and compare the two sounds, but it’s easy to fall victim to the placebo effect brought on by all the marketing messages.
Can a Power Cord Reduce Noise?
As we mentioned, a Hi-Fi mains cable doesn’t affect noise levels noticeably. And that’s reasonable because a power cord isn’t responsible for reducing noise. Handling noise is the power supply’s job.
The power supply includes components that smooth out the incoming AC signal and convert it to DC. As soon as the signal enters the power supply, it passes through an isolation transformer, which filters out high frequencies. The signal then undergoes multiple other stages until it’s flat and has a constant voltage. This way, the power supply takes care of nearly all the noise in your power signal.
If you hear humming or other noise, the problem lies somewhere else in your system. Most likely, you have a ground loop issue, which a Hi-Fi power cord won’t fix.
Things To Consider When Buying an Audio Power Cable
Power cords come in various lengths and sizes with price tags ranging from below $10 to over $1500. Despite differences in materials and specifications, buying the most expensive power cord won’t improve your audio gear’s fidelity.
Let’s talk about a few things to consider when buying an audio power cable.
Length and Diameter
Resistance matters more than anything in power cables. Lower resistance is better because the cord must pass the current to your device, and high resistance prevents that.
A cable’s length and diameter determine its resistance and hence its amperage. Length and resistance have a proportional relationship, while the relationship between thickness and resistance is inverse. That’s because thicker cables contain more electrons that can carry electrical charges.
So, check your device’s amperage requirements and choose the right length and diameter. The American Wire Gauge system uses numerical designations from 2 to 18 to indicate wire thickness. For instance, for a 100 W amplifier, you need a ten gauge cable.
Since power cords transfer electrical current, they may get overheated and cause fires. Shielded cables are more prone to overheating since they can’t transfer the generated heat easily.
It’s a good idea to buy UL-certified cables. UL is a global safety organization that evaluates products in terms of safety and environmental issues. A UL certification on a product means it’s not likely to catch on fire or cause an electrical shock under normal circumstances.
Power cord plugs come in two types: three-terminal and two-terminal. The three-terminal option is common in the US and Europe, including a ground wire for extra safety.
If you’re making a DIY power cord for your audio device, watch this video to learn the right way to connect your plug:
When Should You Replace Your Power Cord?
Although you don’t need to spend money on a new Hi-Fi cable if you already have a working power cord, sometimes you may need a new one. There are two main scenarios:
- Your current power cord is damaged, or the connectors are broken.
- You need a longer cord. For example, you might be rearranging your setup, and the power cord is far from the outlet.
In other situations, you can probably keep using your current cable without any worries.
A Hi-Fi mains cable doesn’t directly affect your sound quality, although it has a minute indirect effect. With a high-end power cable, you’ll have slightly less noise and resistance, but the differences are negligible.
Still, some people think they hear better sound after connecting a high-end cable. This perception is a placebo effect because our auditory memory isn’t strong enough to retain the difference and compare the signals objectively.
So, if you want you’re looking for ways to improve sound quality, other components in the sound chain can make a more significant difference.