How The Speaker Works
A loudspeaker is an electro-acoustic device that converts electrical signals to sound signals. Specifically, the speaker's work is actually to a certain range of audio power signals through the energy (electrical energy-mechanical energy-sound energy) mode into a small distortion and have enough sound pressure level of audible sound.
There are many types of speakers, classification is also varied, Speaker generally based on its working principle, the shape of the diaphragm and the frequency range to be classified.
I. Construction of loudspeaker
Our most common speakers are electric cone-shaped paper pots. Electric cone-type loudspeaker is used in the past we often say into the paper pot speakers, although now the diaphragm is still dominated by paper basins, but at the same time, a lot of polymer material vibrating film, metal diaphragm, with the cone-shaped speaker is called. The cone-shaped paper-pot loudspeaker consists of three parts:
1. Magnetic circuit System (permanent magnet is magnet, the core column is "U Iron or T Iron", guide magnetic Plate, "Hua si").
2, vibration system (vibrating plate, paper basin, sound film, voice coil).
3. Support System (centering support piece is elastic wave, trough frame, cushion edge, terminal plate).
Detailed description of the three systems:
1. Voice Circle: The ring is the driving unit of cone-shaped paper-basin loudspeaker, it is a very fine copper wire (copper/aluminum wire) divided into two layers (four layers) around the bone Plus (paper tube/aluminum sheet/film, etc.), generally around dozens of laps, Speaker placed in the Guide core column and the magnetic flux plate formed in the gap. The sound coil and the paper basin are fixed together, Speaker when the sound current signal enters the sound coil, the sound coil vibration drives the paper basin vibration.
2, paper basin (drum paper): Cone-shaped paper basin speaker cone diaphragm used in a variety of materials, generally have natural fiber and man-made fiber two categories. Natural fiber is often used cotton, wood, wool, silk and so on, man-made fiber just used rayon, nylon, glass fiber and so on. Because the paper basin is the speaker of the sound radiation device, to a large extent determine the performance of the speaker, Speaker so no matter which kind of paper basin, requirements should be lightweight and rigid good, not because of ambient temperature, humidity changes and deformation.
3, Folding ring (Edge flange): The folding ring is to ensure that the paper basin along the speaker's axial movement, restricted lateral movement and set, at the same time to block the paper basin before and after the empty dare to circulate. The material of the folding ring is in addition to the materials commonly used in the paper pots, Speaker and is also made of plastic and natural rubber, which is adhered to the paper basin by hot pressing.
The rigidity or suppleness formed by the cantilever and the elastic wave can affect the moving speed of the sound basin, for the full compliance of the horn, the elastic wave provides about 80%, the suspension provides about 20%, the suspension has two functions, Speaker its original work is to maintain the sound circle in the center of the pole Gap, however
The damping action caused by the suspension is very important for the vibration mode of the cone edge. The thickness of the cantilever and the selection of the material dramatically change the response of the horn, the damping of the cone-basin distortion and the ability to prevent the rear of the cone from reflecting the sound waves can change the distortion pattern in the combination of amplitude and phase, making it a complete component of the cone Basin and a tool for responding
4, centering support piece (Bouncing Wave): Centering support piece is used to support the combination of the sound coil and the paper basin to ensure its vertical and not skew. There are many concentric rings on the centering support plate, so that the sound coil moves up and down freely in the magnetic gap without transverse movement, ensuring that the ring is not colliding with the guide plate. The dust-proof cover on the centering piece is to prevent the outside dust and so on, to avoid the dust and the sound ring friction, and make the speaker abnormal sound.
Classification of speakers
According to the principle of work classification: according to the different principles of work, speakers are mainly divided into electric-type speakers, electromagnetic speakers, electrostatic speakers and piezoelectric speakers and so on.
1, Electric speaker: This kind of loudspeaker uses the electricity conductor to make the sound coil, when enters an audio current signal in the sound coil, the sound coil is equivalent to a carrier flow conductor. If it is placed in a fixed magnetic field, the sound coil will be subjected to a force that is proportional to the audio current and the direction varies with the audio current, depending on the principle that the carrying conductor will be subjected to force in the magnetic field. In this way, the ring will produce vibration in the magnetic field, and drive the vibration of the vibrating film, the vibration of the air before and after the film, so as to convert the electrical signal into sound waves around the radiation. This loudspeaker is widely used.
2, electromagnetic speaker: Also known as tongue Spring speaker, sound source signal current through the voice coil will be made of soft iron material of the tongue spring magnetization, magnetization of the vibrating tongue spring and magnets attracted to each other or demolition, to create a driving force, so that vibrating film vibration and pronunciation.
3, Electrostatic Speaker: This loudspeaker is using the principle of capacitance, will be conductive diaphragm and fixed electrodes in reverse polarity configuration, forming a capacitor. The source signal is added to the two poles of the capacitance, and the electrode is attracted by the change of electric field intensity, which drives the vibrating film to sound.
4, piezoelectric Speaker: the use of piezoelectric materials by electric field deformation of the big principle, the piezoelectric components placed in the audio current signal generated by the electric field, so that the displacement, resulting in a reverse voltage effect, the final driving vibration film sound.
According to the shape of the vibrating film classification: The speakers are mainly conical, flat-shaped, ball-shaped, strip-shaped, thin-shaped and so on.
1, cone-shaped diaphragm speaker: cone-shaped film speaker is the most widely used cone-shaped paper basin speaker, its vibrating film into a cone-shaped, Speaker electric loudspeaker is the most common, the most widely used speakers, especially as a bass speaker applications.
2, flat panel speaker: is also a kind of electric loudspeaker, Speaker its vibrating film is planar, with the whole vibration directly outward radiation sound waves.
Its plane diaphragm is a circular peak nest plate, the middle of which is made of aluminum foil of the peak nest core, both sides of the glass fiber. Its frequency characteristic is flatter, the frequency bandwidth and the distortion is small, but the rated power is small.
3. Ball top-shaped speaker: the ball top-shaped loudspeaker is a kind of electric loudspeaker, its working principle is the same as the paper Basin loudspeaker. The salient feature of the spherical top-shaped loudspeaker is that the transient response is good, the distortion is small, the directivity is good, but the efficiency is low, which is often used as the medium and treble unit of loudspeaker system.
4, Horn Speaker: The working principle of the Horn speaker is the same as the electric type paper pot loudspeaker. The vibrating film of the horn loudspeaker is mostly spherical and can be other shapes. The difference between this loudspeaker and other speakers is mainly in its sound radiation mode, the paper basin loudspeaker and the ball top loudspeaker are by the vibrating film directly to agitate the ambient air to radiate out the sound, is the direct radiation, but the horn loudspeaker is the vibrating film produces sound through the horn radiation to the space, is the indirect radiation. The biggest advantage of the horn loudspeaker is its high efficiency, small harmonic distortion and strong directional, but its frequency band is narrow and the low-frequency response is poor. So it is used as a medium and treble unit in the loudspeaker system.
Frequency amplifier According to the vocal frequency: can be divided into bass speakers, alto speakers, treble speakers, full band speakers and so on.
1, bass Speaker: The main play low-frequency signal speaker is called the bass speaker, its bass performance is very good. Bass speaker to make low frequency lower limit to extend as far as possible, so the aperture of the loudspeaker do is relatively large, generally have 200mm, 300-380mm, such as different caliber specifications of the bass speakers, with large input power. In order to increase the limit value of the amplitude of the paper basin vibration, the soft and wide support edge is used, such as the skin edge, the cloth edge, the insulating edge, etc. In general, the larger the caliber of the subwoofer, the better the low-frequency sound at playback, the greater the input power.
2, alto speakers: The main play if the speaker signal is called the Alto speaker. The alto speakers can achieve frequency convergence when the bass speaker and treble speakers replay music. Because the intermediate frequency is the dominant range, and the person's ear is more sensitive to the intermediate frequency, the sound quality of the alto loudspeaker is higher. There are paper basin shape, ball top shape and the number of barrel shape and other types. As the alto loudspeaker, the main performance requirement is the sound pressure frequency characteristic curve flat, the distortion is small, the directivity is good and so on.
3, Treble Speaker: the main high frequency signal of the speakers are called treble speakers. Treble speakers to make high-frequency playback of the upper limit of the frequency of auditory upper ear 20kHz, so the aperture is small, the vibrating film is more toughness. Compared with the low and alto loudspeaker, the performance requirements of treble loudspeaker are the same as that of the Alto unit, and the upper limit of playback frequency is higher and the input capacity is large. The common tweeter has a paper basin shape, a flat plate shape, a ball top shape, a ribbon capacitor shape and many other forms.
4, full-band speaker: Full-band speaker is capable of simultaneously covering the bass, alto and treble bands of speakers, can play the entire audio range of electrical signals. The theoretical frequency range is required from dozens of Hz to 20kHz, but in practice it is difficult to use a loudspeaker, so most of them are made of two-paper basin speakers or coaxial speakers. The dual-paper basin speaker is a small-caliber paper basin in the middle of the loudspeaker, which is used to replay high-frequency sound signals, thus facilitating the elevation of the upper value of the frequency response. Coaxial speakers are mounted on the same central axis with two different caliber bass speakers and tweeter.