What is the basic principles and roles of loudspeakers ?

Last Update Time: 2018-12-15 11:35:54

Loudspeaker is an electroacoustic converter that converts analog speech signals into sound wave. It is widely used in various electronic devices, such as radio, tape recorder, audio equipment, etc.

1.Effect

 When the audio signal current flows through the sound coil of the loudspeaker, the alternating magnetic field produced by the audio current in the sound coil and the strong constant magnetic field produced by the permanent magnet causes the mechanical vibration of the sound circle will be pulled or pushed out, and the amplitude varies with the direction and size of the current (the electrical energy is converted into mechanical energy).

The sound circle is up and down vibration drives the vibration of the paper basin closely connected with it, so that the large area of air around it vibrates accordingly, converting mechanical energy into sound energy.

 

2.Measure the use of speakers

 When the output impedance of the loudspeaker device is equal to the rated impedance of the loudspeaker, the maximum power of the loudspeaker is obtained, and if the utility model is not matched with each other, the output impedance of the loudspeaker is the largest,  the sound quality is poor; heavy causes the loudspeaker and the amplifier machine to be damaged.

The rated impedance of the loudspeaker is not equal to the DC resistance of the loudspeaker voice coil, and the method can be used to measure the DC resistance of the loudspeaker voice coil using the electric barrier of the multimeter, the measured resistance is multiplied by the coefficient of 1.25, which is approximately the nominal impedance of the loudspeaker.

The impedance of the loudspeaker is like 42, 82, 162 and so on. If the value of the calculation with a decimal part, should be with 412, 80, 1602 and so on the most close to the value. For example, the DC resistance of a loudspeaker is 6.30. The number is multiplied by 1.25, and the calculated value is 7.8752, and the impedance is 80.

 

3.The power of the loudspeaker

The power of the loudspeaker is divided into rated power, maximum power, minimum power and instantaneous power.

 

(1)Rated power is also called nominal power. It refers to the average power loss of the speaker which is made for a long time without any obvious loss.

 In the actual design, the new set power of the loudspeaker is left with a margin, and the label is marked. The loudspeaker works at rated power, the distortion will not exceed the specified value, and the voice coil will not overheat. In order to get a better sound quality, the speaker's power should be less than its rated power, and the power input should be between 1 / 2 ~ 2 / 3 of the rated power.

 

(2)The maximum power ( also known as the maximum load power ) is the maximum transmission power that the loudspeaker bears when working continuously for a long time, which is usually 1 to 3 times of the rated power.

 

(3)The minimum power is the reference power that the speaker can drive to work.

 

(4)Instantaneous power, also known as instantaneous power, refers to the maximum power that the loudspeaker can withstand in a short period of time ( 10ms ), generally 8-30 times of the rated power. What is usually said about the power of the loudspeaker is the rated power of the loudspeaker. The rated power of the loudspeaker can be directly seen from the label, and can be inferred roughly according to the size of the loudspeaker when the label is off. The bigger the general caliber, the greater the power.

For the sake of accuracy, a loudspeaker with the same caliber, same type and clear mark can be found, which can be basically determined.

 

4.Distinguish of High, Medium and Bass Loudspeakers.

Maintenance can be based on the structure of the speaker, the size of the aperture and the degree of softness of the paper basin to be visually discriminated.

 

(1)The horn type loudspeaker is a tweeter.

 

(2)In addition, there is also a special tweeter, commonly known as the treble head or trumpet barrel, which is electrically operated and also useful in piezoelectric or capacitive mode.

 

(3)The top of the ball loudspeaker ( soft ball top and hard ball top ) are mostly high-pitched or mid-tone speakers, which are usually used in conjunction with cone-basin bass loudspeakers. The baritone loudspeaker is larger than the back cavity of the top tweeter.

 

5.Discrimination of the quality and performance of the loudspeaker.

When purchasing and using the loudspeaker, use the multimeter RX1 block to measure the DC resistance of the two ends of the loudspeaker terminal ( that is, the DC resistance of the voice coil ). If the DC resistance is close to the rated impedance ( about 0.8 times the rated impedance, usually in the range of 4 to 162 ),  and the loudspeaker sends out a " click " sound, it shows that the loudspeaker is basically normal. The bigger the click sound, the higher the efficiency of the electro-acoustic conversion; the sound of " Kala " is crisp and clean, indicating the better sound quality. If the " Kala " sound is small or even, but the DC resistance is normal, indicating that the voice coil is stuck. If there is no " click " sound, the DC resistance is infinite, indicating that the lead wire of the loudspeaker is broken or the voice coil is open.

 

6.Discrimination of speaker phase .

The phase of the loudspeaker is also called positive and negative polarity, which means that when the DC current is connected to the loudspeaker, the paper basin moves forward, and the current flow human terminal is the positive electrode. Because this kind of regulation is arbitrary, it can be divided into positive and negative pole when working alone. When multiple loudspeakers are connected in parallel, their orthodoxy should be connected to the positive electrode and the negative to the negative; when a plurality of Yang city devices are connected together, the positive pole of one loudspeaker should be connected with the negative pole of the other loudspeaker, which can be connected in turn, so that multiple loudspeakers can be in phase work.

 

This article is from Allicdata Electronics Limited.