How Do Speakers Work

Ever wondered what you'd find if you opened a speaker and took a look inside? Want to learn how a speaker works so you can choose the best speaker for your space? Here's your chance to find out what's inside a speaker.

The Drivers
The core of any speaker is its drivers. Speakers use two different driver types, a cone or a diaphragm, which vibrate to produce sound waves. Depending on the type of construction, a speaker cone may be made of metal, plastic or paper. The wide part of the cone is attached to the suspension, or surround, and from there connected to the basket, or the metal frame of the driver. The narrow end of the cone is connected to the voice coil, which translates the electricity to vibrations and moves the driver. In diaphragm construction, the speaker cone is a dome that extends out instead of tapering inward.

How Sound Is Made
When a speaker is used, the voice coil vibrates, using electromagnetic principles and a permanent magnet to move back and forth as the current alternates from positive to negative. These rapid vibrations move the diaphragm or cone, which then produces sound waves. Faster vibrations produce sound waves at higher frequencies, while slower vibrations produce low-frequency sounds. The magnitude of the vibrations determines the amplitude of the sound; more extreme vibrations produce louder sounds, while minute vibrations produce very quiet sounds.


Driver Size and Multiple Drivers
Different-sized drivers vibrate more readily at different speeds. Woofers are the largest drivers, and they vibrate slowly to produce low-frequency sounds. Because low-frequency sounds are the most difficult to hear, you sometimes see powered woofers operating at a separate volume level to magnify the amplitude of low-frequency sounds. Tweeters are the smallest drivers, and they vibrate extremely quickly to produce high-frequency sounds. Midrange drivers are usually somewhere between woofers and tweeters in size and are designed to fill in the middle ground to produce rich, full sound. Because different drivers produce different frequencies, speakers often have two or more drivers; a woofer, a tweeter and sometimes a midrange driver all contained in the same speaker.

The Crossover
When you have multiple drivers in the same speaker, a crossover separates the electrical impulses to send the low-frequency sounds to the woofer and the high-frequency sounds to the tweeter. The crossover's effectiveness has a big impact on a speaker's sound quality. Passive crossovers use inductors and capacitors to split the signal, since capacitors conduct high frequencies well while inductors conduct low frequencies well. Active crossovers are separate electronic devices that sort the frequencies before the signal goes to the amplifier. Active crossovers give you the ability to set specific frequency cutoffs depending on your speaker setup, while passive crossovers are limited by the capacitors and inductors installed in the speaker. Unfortunately, active crossovers are very expensive and require separate amplifier outputs for your speakers, so passive crossovers are far more common.

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