(1) Performance and characteristics of car speakers
Some people believe that the speakers of car audio systems are exactly the same as those of household appliances. This viewpoint is incorrect, as they are basically the same in terms of frequency response, power, impedance, sensitivity, etc. However, there are significant differences in manufacturing technology, materials, structure, and usage environment.
The usage environment is different:
1) Temperature: When using home appliances speakers in a room, the temperature difference is small, while when the car is parked outdoors, it is extremely cold and hot, and the temperature inside the car varies greatly with the climate;
2) Moisture-proof: Cars must be protected from moisture during rain, walking on waterways, and washing, so car speakers, especially the speakers, should be moisture-proof.
3) Dust prevention: When using household appliances speakers in a room, there is less dust, while there is more dust in the car. A dust cover is needed to prevent dust from entering the sound coil and causing noise due to friction.
4) Vibration: Car speakers are subject to the vibration and impact of car movement anytime and anywhere, and should be designed to be firm and not loose.
5) Noise: Considering various noises and reflections inside the car, different materials are used, and various design methods are adopted to offset different noises.
6) Sound field positioning: The installation position of the car's speakers is limited, and in order to listen to sound field positioning, the high pitch angle is designed differently.
7) Low impedance: The power supply voltage of the car is low, and in order to obtain high power, the impedance of the speaker is relatively small. 4 Ω and 2 Ω are often used, and double voice coils are used. The parallel method can reach 2 Ω or even smaller, which is rarely used in home audio systems.
(2) Working principle of speaker
The speaker includes a bass unit, a mid-range unit, and a treble unit. These three units are responsible for different frequencies, and most speakers work based on the same principle.
Like a typical moving coil horn (most car horns belong to this category), when current flows through its voice coil (thin conductive wire), an electromagnetic field is generated, which is perpendicular to the magnetic field of the permanent magnet on the horn, causing the moving coil to move within the gap (the gap between the voice coil and the magnet). The mechanical force generated by this movement causes the paper box attached to the sound coil to move vertically, up and down (vibrate), thereby moving the air (causing it to vibrate) and transmitting audio to the human ear, achieving the goal of restoring sound for human listening and achieving the conversion of electrical energy to sound energy.
(3) Classification of speakers
1) According to the frequency of speaker playback: full frequency speaker, tweeter, mid-range speaker, and bass speaker
2) Classified by size: Common dimensions of tweeter units (usually referring to the diameter of the voice coil): 25mm (1in), 35mm (1.38), etc; The unit dimensions of mid to low frequency speakers (usually referring to the installation diameter) include 80mm3in, 100mm4in, 130mm5in, 165mm6.5in, etc; Dimensions of subwoofer units (generally, subwoofer size refers to installation diameter): 200mm8in, 250mm10in, 300mm12in
3) Classified by performance and purpose: unit speakers, set speakers, coaxial speakers, and subwoofers.
Unit speaker: low-end product, low bass not thick, high pitched not bright
A set of speakers consists of tweeters, mid-range speakers, frequency dividers, etc. Commonly used are two and three dividers, which have the advantage of facilitating the positioning of the sound field.
A coaxial speaker is a high and medium pitched speaker placed on a coaxial or chassis. Easy to install and consistent sound source.
Bass speakers are usually installed in specially made bass boxes with a diameter of 200mm or more. Greatly improving the listening experience inside the vehicle, especially during high-speed driving, the bass will be greatly attenuated. It is necessary to add a bass system
