What Is a Speaker?
A speaker is a component that converts the varying electrical signal given to it into a sound wave in the air. Unlike a buzzer, it produces music/speech over a wide frequency range. Conversely, the component that converts sound in the air into an electrical signal is the microphone.
How Does It Work?
The signal is applied to a voice coil within the field of a fixed magnet. As the current changes, the coil moves back and forth, and the attached diaphragm (cone) pushes the air to create the sound.
Impedance
Speakers are referred to by impedance (usually 4Ω or 8Ω). This value must match the amplifier to be connected; too low an impedance draws excessive current from the amplifier and causes damage.
| Parameter | Meaning |
|---|---|
| Impedance | 4 / 8Ω (matched to the amp) |
| Power (W) | Max power it can withstand |
| Frequency range | The tone band it produces |
Power (Watts)
A speaker's power rating shows the maximum electrical power it can withstand without damage. If the amplifier's output power exceeds the speaker's rating, the voice coil can burn out.
Where Is It Used?
Phones, televisions, music systems, PA/announcements, toys and devices needing audible feedback.
The Need for an Amplifier
A speaker needs relatively high current; an MCU or small signal can't drive it directly. An audio amplifier is placed in between to raise the signal to the power needed to move the speaker.
Common Mistakes
- Impedance mismatch: a low-impedance speaker overloads the amplifier.
- Power overload: if the amplifier power exceeds the speaker, the coil burns.
- Direct drive: feeding the speaker directly from an MCU without an amplifier.
Frequently Asked Questions
Can a 4Ω speaker connect to an 8Ω output?+
What's the difference from a buzzer?+
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