We expect items like speakers, hi-fi amplifiers, and CD players to emit crystal-clear sounds. After all, it is their primary purpose. But, how to measure this attribute? Well, the device’s signal-to-noise ratio is always a good indicator.
In this piece, we’ll examine this aspect and how it affects the sound quality. Along the way, we’ll define some fundamentals as well, just to cover all grounds.
What Is Noise in Audio Devices?
The ‘background’ noise created by your audio device is an unwanted signal or an electronic hiss. Sometimes it sounds like a static or vibrating hum. The best way to detect it is to play press the ‘play’ button without selecting any media. Next, simply crank the volume up. Soon, you’ll hear a sound reminiscent of hissing or humming. This phenomenon is always present, no matter the audio device.
However, as long as the incoming signal of your amplifier is strong and offsets this noise, the audio quality will be clear. In other words, that is the signal-to-noise ratio (S/N ratio) of that device. Preferably, it should be higher than 1:1.
On the flip side, no amount of volume can ‘drown’ this inherent noise on bad audio output. Not even if we turn the wheel up to 11! We’ll only manage to amplify the humming with such methods. So, that won’t do us any good.
In other words, if the background noise goes “in tune” with what you’re trying to play, the output will be distorted. Such unpleasantness will prove persistent, too. Hence, the S/N ratio is crucial for all audio equipment.
Simply put, a positive S/N value equals higher quality sound. It means the signal stays louder than the unwanted hissing. Therefore, S/N it’s a numerical estimate you should keep an eye (and an ear) on.
What is A Good Signal-To-Noise Ratio?
The S/N ratio is specified in decibels, and a higher signal-to-noise ratio means better sound quality. For instance, if your device’s S/N ratio is 50 dB, the output sound will be 50 dB louder than the background noise.
Given this explanation, you might wonder what is considered a good signal-to-noise ratio for an amplifier? Well, anything above 80 dB is an excellent S/N ratio. In practice, you should easily find audio devices with this potency.
How Important of A Factor Is the S/N Ratio?
Understanding the effects of the signal-to-noise ratio will always come in handy. There are many living-room peripherals with audio outputs of varying qualities. By knowing their strong suits, you’ll be able to utilize them better.
This simple example illustrates the result of a low S/N ratio. Suppose you are talking to a person inside of a moving truck. Since the truck is rushing at full speed, the engine and the surrounding noises create an ambient sound of 60 dB. But, even if a normal human conversation produces more than 60 dB, you’ll have to make up for this difference. As a result, you’ll have to ‘outmatch’ the ambient sound to be able to hear each other well. In this case, you might even have to ‘yell’ up until you reach 120 dB. This might prove exhausting, but at least it will be articulate.
Similarly, an amplifier needs to create a loud output signal to offset the noise. Again, that strength is measured in decibels. The higher that number, the clearer the sound. For your car, the S/N ratio of your amplifier should be between 80-90 decibels. That isn’t a universal value, though. Some engines are simply noisier than others. So, in some cases, only a better audio output can allow you to enjoy the music of your choice.
Now, if the S/N ratio of an amplifier is low, you won’t be able to make out much. However, the amplifier shouldn’t necessarily be the one to blame. It might be that your engine is acting up. Or simply, you haven’t set the S/N ratio correctly.
How Much Attention Should You Devote to the S/N Ratio?
Generally speaking, having a good signal-to-noise ratio is essential to consider while buying an amplifier. That said, after a specific value, there are diminishing returns. In other words, you shouldn’t dismiss an amplifier due to a 10dB difference. It’s better to know the range you are comfortable with and not overreach. At least, this viewpoint might save you money. If you buy overly potent equipment for your home, it might forever stay underused.
When pinning two amps featuring similar dB ranges against each other, consider the other factors too. Their asking prices might prove more important than a small S/N difference. For instance, if the dilemma boils down to an 84 or an 86 dB amp – opt for the cheaper one, no exceptions.
Can You Calculate the S/N Ratio?
Although most audio devices specify the S/N ratio, it might not stay like that forever. That ratio will too plummet as the device ages, getting noisier and noisier. When that happens, calculating the current S/N values can be more challenging. Even some complex equations might take place, including logarithmic values.
Generally, though, simpler methods will work. To calculate the ratio, one only has to know the dB strength of the background noise. Then, simply subtract that value from the output signal of the device. The equation will point to the optimal S/N ratio for that amplifier.
However, things might get convoluted if your device’s measurements are denoted in watts or voltage. When dealing with watts, divide the desired output signal by the noise and multiply the answer by 20. If working with voltages, multiply it by 10 to get the required ratio.
Buying an amplifier with the right S/N ratio is essential for truly enjoying your favorite music tracks. It determines the clarity of sound emitted, which is, in practice, the most important aspect. If the signal-to-noise ratio falls in the negative, the output will be distorted and irritating to listen to.
Hence, we must ensure this attribute ahead of time. Plus, we should keep in mind the purpose of the purchase. If it is for home equipment, we don’t need a potent amplifier. However, equipping a vehicle with a sound system is another story.
John Fleming is the senior editor for Audiophilez.com, covering everything from headphones to smart speakers. He is a graduate of Music Production and Technology. Before Audiophilez, John began his career as a staff writer for two different magazines, where he became a skilled storyteller across different mediums. When he isn’t writing, he can be found biking, reading books, and playing the piano.