Here’s a fun fact for you: about ninety percent of all the electronics we use on a regular basis have speakers. Let’s start with the most obvious ones.
Your smartphone/tablet/smartwatch has one. So does your laptop, and so does your TV.
At the risk of sounding like we’re on the verge of an apocalyptic Terminator-like scenario, speakers are EVERYWHERE. Heck, even your microwave has one that stops you from burning down the house every time you make popcorn.
Understanding What Makes a Speaker Sound Great
Speaker technology has come a long, long way from Alexander Graham Bell’s first working loudspeaker. In case you didn’t realize it, this is the guy that invented the telephone back in 1876, a communication device that relied heavily on the accurate transmission of sound.
Speaker technology hasn’t changed much from its first simple iterations. Speakers are still devices with magnets and diaphragms that move back and forth depending on vibrations generated by different frequencies of sound.
Even with that overly simplified definition, most people still find it hard to tell what exactly it is that makes a speaker good.
If you’re one of those people, today is your lucky day, because we’re going to take a step-by-step approach into what makes the difference between an excellent speaker and a low-quality one, and why those cheap backstreet boomers will never measure up to giants like Bose and Sony.
Speaker Tech 101: The anatomy of a speaker
To better understand why some speakers produce better sound than others, let’s deconstruct a speaker right now to see exactly what it contains.
A speaker or a driver (which is the “tech” term given to a single speaker) is comprised of a magnet, a copper coil, and a membrane (a thin sheet of material, if you will). The copper coil is inside the magnet, so to speak, and onto it, the membrane is attached.
When connected to an electrical source, changes occur inside the electrical field of the magnet. Because it is situated inside the magnet, these changes cause the copper coil to start vibrating.
These vibrations then move the membrane, which is attached to the coil, making it move the air in front of the driver to produce sound.
Changes in the flow of electrical current cause the membrane to push back or pull into the magnet depending on the direction of the flow.
The current flows in one direction then another in quick succession to mimic the frequency of the sound being produced.
How does this interpret into actual sound, you ask? Well, it’s simple. Low sounds have lower frequencies, and this means that the membrane moves back and forth only a few times a second.
For deep bass sounds, it could move as few as 24 or 36 times a second.
High frequencies like treble are a different story.
To create such sounds, the membrane can move tens of thousands of times — all in a single second!
Sound is all about the frequency of vibrations. Very high sounds have similarly high frequencies that cause the membrane to move several thousand times in a second.
Low-frequency sounds are just that — sounds that require the membrane to move less frequently each second to generate them.
Now that we have that knowledge, we still aren’t fully equipped to distinguish between good and bad speakers. For that, we need to go a bit deeper.
What makes a great speaker?
Just like a great screen is decided by its ability to recreate colors and images, the sign of a great speaker is its ability to accurately recreate the sound.
Every trumpet, every guitar strum, and every chant should be heard as clearly as it would be on a live platform. Okay, maybe not on a live platform because no speaker can replicate live sounds, but it should come very close.
How can you tell whether a speaker is doing a good job of being a speaker?
1. By Checking Its Frequency Response
The frequency response of any speaker is the variation observed in the volume of the speaker’s output at various frequencies. Some speakers have a tendency to add “color” to sounds produced at different frequencies.
This is never a good sign.
The easiest way to spot a great speaker is by checking its frequency response. Frequency response can be observed in the loudness (or softness) of the sound produced by the speaker at different frequencies.
Speakers with the least amount of variation in loudness between frequencies are considered excellent speakers.
Their frequency response charts tend to be flat for the most part as the sound is produced at an even volume regardless of the frequency.
Speaker construction and design is what affects its frequency response. On that note, let’s move on to another important element of a good speaker: the material.
2. Cone Material Matters… It Matters A Lot
Why is cone material so important to the speaker and sound quality? Don’t they all do the same thing, which is to push air out at different frequencies?
Cones can and be made out of all kinds of material. They can be made from ceramic, aluminum, glass fiber, polypropylene, or good old paper. Each of these materials affects the overall sound quality of the driver. Here’s why.
The cone works very much like a piston when pushing out sound. If a cone is too soft, it will flex. This isn’t good for sound quality at all. Flexing cones are some of the biggest reasons why sound becomes distorted at various frequencies.
High-end speaker manufacturers try to minimize this flex as much as possible by using more rigid materials. While the materials we’ve mentioned above are the most commonly used in speaker cone construction, they’re certainly not the only ones.
Clay impregnated cones are common as well, especially in speakers meant for extra low resonance. Polypropylene fairs extremely well in mid-range drivers, and you’ll find most high resonance drivers with paper or lighter cone materials.
Everything in a speaker is made from a different material, and every material has a say over the overall sound quality.
Poorly built or cheap speakers tend to suffer from sound distortion. Now you know exactly why that happens.
3. The Science of Sound Design, and why it affects Sound Quality
A speaker’s materials are one thing; how they’re assembled is a completely different thing. Both can have a great impact on the quality of sound it produces.
After all, even the greatest recipes amount to nothing in the hands of someone who doesn’t know how to follow the process. Great materials are great ingredients, but without the appropriate assembly procedure, they can result in a very disappointing product.
This is where sound design comes in. Sound design engineers concern themselves with the housing of the speaker. They worry about how the enclosure will look like and what that will do to the sound.
Without someone worrying about things like these, speakers would be ineffective, and quite terrible to listen to.
The sound design seeks to eliminate interferences in sound production. For instance, enclosing a driver in a compartment that’s entirely too large results in a lot of reverberation, which can create cross noise and affect the fidelity of the sound.
Similarly, if the driver or other components aren’t properly and firmly installed, then they will rattle and ruin the sound by adding some much-dreaded distortion.
Sound design is especially important in speakers with multiple drivers. Speakers that have more than one driver within the compartment are generally better at delivering sounds at all frequencies.
However, this all depends on one component, a component known as the crossover circuit.
The crossover circuit’s function is to route audio signals to specific drivers based on frequency. Here’s an example of how that works.
Most of the speakers you’ll find today have at least two drivers: a bass driver known as a woofer, and a treble driver that we call the tweeter.
Sounds of higher frequencies are automatically routed to the tweeter, while deeper, low resonance sounds get diverted to the woofer. This is only possible because of the crossover circuit, which can make speakers with the same drivers sound totally different.
The difference between a good speaker and a poor one sometimes boils down to the number of drivers it has and the presence (or absence) of a crossover circuit to direct the audio signal to specific drivers based on their range of frequencies. Such setups play on the strength of specific drivers because all drivers produce better sound on certain frequencies.
4. The Art of Sound Imaging
All of what we’ve talked about so far can be done by an automated manufacturing line. In other words, it is the science of speaker construction.
Unfortunately, sound can’t be perfected by science and great materials alone. The accurate sound production is, for all intents
and purposes, an art form, which is why the final, and arguably most important step in the building of a speaker relies solely on the human hearing ability.
Even after tweaking all the components of a speaker to achieve an ideal resonance frequency, a speaker is still not ready for action. What remains, and sound technicians will tell you that this is what matters the most, is sound imaging.
What is sound imaging? Simply put, sound imaging is how you interpret the audio produced by the speaker to form a meaningful sound image in your head. Let’s break that down a little bit.
Ever wondered how you can tell that a sound is farther or closer from you even when the speaker remains at the same distance?
Or how a voice sounds like it’s coming right from the center of your audio setup despite having two or more speakers set far apart from each other?
Or how some sounds, despite being lower in volume, can still be heard crisply over other sounds?
All that is attributed to quality sound imaging. A speaker manufacturer’s greatest product is nothing if it doesn’t create good sound images.
Imaging has nothing to do with the specs of the speaker and everything with a manufacturer’s proficiency when it comes to sound design.
How do they achieve the perfect sound image? By testing it out themselves. Over and over again until they get an ideal balance.
Sound imaging is played by ear, which means that no matter how advanced the technology a manufacturer uses is, the sound quality of their product will ultimately be made better by listening and adjusting.
Why the perfect speaker isn’t the perfect speaker
Remember when your friend got that home theater system for his condo and swore that it was the best thing ever?
Remember when you decided to buy the same home theater system for your smaller apartment only to find that it didn’t quite hit the spot?
There’s a simple explanation for this: the perfect speaker doesn’t exist. However, there can be the best speaker for your homeroom, the best speaker for your bedroom, and the best speaker for your friend’s larger condominium. Why is this?
Only you can decide if a speaker sounds good enough for you.
What your friend may consider the best speaker might sound a little off to you (maybe you can detect just a hint of distortion, or you just can’t seem to find the mute button hard as you try) and that’s completely normal.
Different people will prefer different speakers over others.
Nevertheless, if it all boils down to overall speaker quality including construction, here’s how to pick out a top-notch product:
- Check its frequency response. If the volume of its output changes drastically on different frequencies, that’s a bad speaker.
- Check the quality of the materials used. Cone material is admittedly the most important as far as materials are concerned. Check that it won’t distort sound at certain frequencies.
- Check the number of drivers it has. One driver is enough to make the sound, but two drivers are even better. And so are three or four. You get the point, right?
- Check the assembly. Speakers, especially those with more than one driver, have a nasty habit of having components that are not properly braced. The result is that annoying rattle that comes at high volumes or at different frequencies.
- Finally, check that the speaker will serve the purpose you intend to use it for before purchase. Most manufacturers won’t give you this option, but some allow you to test it out for a period of time to see if it’s the right fit.
So there you have it, a great sounding speaker somewhat determined by each individual listener.
Yes, you can have a speaker perform well on a technical level, but after that point, simply try and enjoy the experience.
There is a lot of enjoyment that can be had when spending some time to become more aware of great sounding audio.