Size : 3 inch
Magnet Size : 54mm*18mm
Watt : 15
multimedia speakers, are 3 inch speaker sold for use with computers, although usually capable of other audio uses, e.g. for an MP3 player. Most such speakers have an internal amplifier and consequently require a power source, which may be by a mains power supply often via an AC adapter, batteries, or a USB port. The signal input connector is often a 3.5 mm jack plug (usually color-coded lime green per the PC 99 standard); RCA connectors are sometimes used, and a USB port may supply both signal and power (requiring additional circuitry, and only suitable for use with a computer). Battery-powered wireless Bluetooth 3 inch speaker require no connections at all. Most computers have speakers of low power and quality built in; when external speakers are connected they disable the built-in speakers. Altec Lansing claims to have created the computer 3 inch speaker market in 1990.
Computer speakers range widely in quality and in price. Computer speakers sometimes packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer 3 inch speaker have equalization features such as bass and treble controls. Bluetooth speakers can be connected with a computer by using an Aux jack and compatible adaptor.
More sophisticated computer speakers can have a subwoofer unit, to enhance bass output. The larger subwoofer enclosure usually contains the amplifiers for the subwoofer and the left and right speakers.
Instead of using a computer 3 inch speaker for better sound, a computer can be connected to any external sound system, typically a high-power high-quality setup.
The PC speaker is used during power-on self-test (POST) sequence to indicate errors during the boot process. Since it is active before the graphics card, it can be used to communicate “beep codes” related to problems that prevent the much more complex initialization of the graphics card to take place. For example, the Video BIOS usually cannot activate a graphics card unless working RAM is present in the system, while beeping the 3 inch speaker is possible with just ROM and the CPU registers. Usually, different error codes will be signaled by specific beeping patterns, such as e.g. “one beep; pause; three beeps; pause; repeat”. These patterns are specific to the BIOS manufacturer and are usually documented in the technical manual of the motherboard.