Speakers are an element of everyday life that often goes unnoticed precisely because they have been with us for many years, but have you ever wondered how they work ? And how does the PC handle the audio signal that we hear through the speakers? In this article we are going to tell you everything.
Speaker technology is the cornerstone of the audio industry, servicing everything from your car’s sound system to the tiny Bluetooth headphones you use to listen to music. Although most people don’t know the ins and outs of their design, knowing how they actually work can make the difference between buying the right or wrong speaker system, and is also extremely valuable when trying to repair a speaker that doesn’t work.
How do PC speakers work?
The fundamentals of speaker technology have not changed in the last 100 years, just like the usual TRSS connector (known as a jack). The 1924 dynamic loudspeaker from Edward Kellogg and Chester Rice is still the most widely used technology today, although there have obviously been some advancements in technology and quality since then.
The fundamental principle of PC speaker technology is the transfer of energy from one state to another; To be more specific, transform the electrical waves that the PC sends to the speakers (and this can be extrapolated to any other audio reproduction device) into sound pressure waves in the air so that your ears can detect them.
The mechanism used to achieve this is quite simple: there is a cone in the speaker that vibrates, pushing and pulling the air to create the sound waves. The conversion of electrical energy to mechanical occurs through a combination of electromagnetic coils and a magnet attached to the cone; This coil moves the speaker cone back and forth as its electromagnetic field changes with the electrical current flowing through it.
However, speakers require much more power to push and pull air to produce sound than electrons moving through the signal wire. Therefore, loudspeakers need an amplifier to drive the electrical signal sent by the low-power PC to a higher-power state to drive the loudspeakers. Modern solid state amplifiers increase current to produce enough watts of power, while older tube amplifiers directly operate at high voltages.
Lower-powered and home speakers always include a built-in amplifier, thus ensuring optimal power transfer to the speaker. However, more powerful hi-fi speakers often require an external amplifier, which requires careful attention to power output and speaker impedance matching to ensure that the setup works properly.
Tweeters and Subwoofers
Obviously, not all speakers sound the same. An important factor in the sound of a speaker depends on the size of the coils: if you wonder why a small in-ear headphones or the Amazon Echo smart speaker sound “little” and lack oomph, it’s because they have a tiny driver that it cannot cover large wavelengths, necessary for low frequencies, or it does not have power in its amplifier to reproduce them without distortion.
There is a reason why the size of the speaker affects the frequency of the sounds it is capable of producing. Smaller speakers move easily and quickly without requiring too much power, making them ideal for high frequencies; Larger cones can move more air and spread out to cover larger wavelengths of lower frequencies, which generate low-distortion bass sounds. However, this makes them bigger and heavier, and they take longer to fully move so they require more power. This is why subwoofers are always big, heavy, and packed with power.
In the most acceptable speaker setups, you’ll find a combination of cone sizes combined with crossover EQ circuitry to filter the signal. Thus, you can see large cones for powerful bass known as woofers to small tweeters for high frequency details. Larger home theater and hi-fi setups also often include an even larger low-frequency speaker called a subwoofer.
There is no exact correlation between the size and quality of specific frequencies. For example, tweeters come in a wide variety of types, from traditional cones to piezoelectric crystal, ribbon cones, and electrostatic diaphragm types.
The inner workings of the speakers
It is not only the size of the cone that affects the sound of the speakers, but all its internal components can make a noticeable difference in the sound, including even the type of materials and the shape of the soundboard since the sound is absorbs and reflects off the speaker body. The passive radiator and port design also contributes to the overall frequency response.
Each speaker is built with the following components:
- Diaphragm or cone: as in our bodies, this is the part responsible for vibrating and moving the air. This term is used interchangeably as cone. Tweeter diaphragms can be made from a thin ribbon, although polypropylene plastic is the most common material. Other materials include fiberglass, carbon fiber, aluminum, and PET plastic, which affect the weight and motion of the cone.
- Surround : keeps the diaphragm in place while allowing it to vibrate. The most common materials are rubber (rubber) and foam.
- Coil : a coil of wire connected to the back of the diaphragm. The moving coil reacts to the magnetic field produced between it and the magnet when the current sent by the PC passes through it. This provides the force that moves the cone and produces the sound. The coils can hang above or below the magnetic material, which has advantages and disadvantages for coil mass, sensitivity, and linearity of motion. Suspended coils tend to be reserved for high-end speakers.
- Magnet – This permanent magnet sits behind the speaker cone and interacts with the changing magnetic field to move the speaker. Different sizes and materials of magnets slightly alter tonal qualities, and common materials include neodymium, ferrite, alnic, or samarium cobalt.
- Soundbox – A box, usually made of metal or wood, that contains all of the speaker components listed above.
- Spider : it is placed between the diaphragm and the resonance box, ensuring that they do not touch.
While the core concept of speaker design is essentially the same in the vast majority of audio products, there is a lot of variation in these internals. Product purpose, cost, and material choices have a lot to do with how speakers sound.