According to the speaker structure, it can be divided into closed speakers, inverted speakers, empty paper cone speakers, labyrinth speakers, horn speakers and other types.
1 Enclosed speakers
The enclosed sound box is the simplest speaker system among all the sound boxes. Its shape and structure are all sealed except for the opening for installing the loudspeaker in the front, and the box is filled with porous fiber sound-absorbing material. When an audio current flows through the speaker, the speaker diaphragm vibrates, pushing the sound wave in front of the speaker cone to radiate around, while the sound wave behind the cone is absorbed by the sound-absorbing material, which will radiate the sound wave forward and backward The radiated sound waves are completely isolated, thereby effectively avoiding the acoustic short-circuit phenomenon. In addition, due to the existence of the closed box, the rigidity of the resonance of the motion mass of the speaker is increased, the maximum resonance frequency of the speaker is increased, and the low frequency response is improved. The sound of this speaker is a bit deep, but the bass analysis is good. Since the enclosed box is generally small and has a limited volume, the air in the box forms an additional elastic effect on the speaker. The air cushion behind the paper cone will exert a counter-driving force on the paper cone, which will increase the natural resonance frequency of the speaker. , And make the low frequency response worse, so nowadays, speakers with low resonance frequency are often used to make speakers. Enclosed speakers have low sensitivity, but can use amplifiers with high output power, and their structure is relatively simple, easy to design, and convenient to place, so they are widely used in homes and small entertainment venues.
Except for the speaker opening, the rest are all closed speakers. The front and rear of the speaker cone are divided into two airtight spaces, one is an infinite space outside the box, and the other is a closed box space with a certain volume, eliminating the speaker paper Acoustic short circuit and interference phenomenon before and after the basin, but due to the sealing of the box, the vibration of the paper cone will cause the air in the box to produce repeated compression and expansion processes, so each part of this box should have sufficient strength and airtight performance, otherwise, It is easy to produce plate vibration and affect characteristics. Its main feature is pure sound, but low sensitivity, suitable for home audio.
2 Inverted speaker
Also called bass reflex speakers, this kind of speakers have one or more sound holes in the front of the cabinet. The shape and structure of the speakers have various opening positions and shapes. Some have only one hole, and some have several holes. Most of the holes are also equipped with sound ducts, and the shapes of sound ducts are also varied. Its working principle is: the sound wave radiated by the loudspeaker resonates with the air in the box, and then the phase of the sound wave is reversed by 180 degrees through the sound tube and radiated from the opening of the sound tube. Since the sound wave radiated from the back of the speaker cone is exactly in phase with the sound wave radiated forward from the speaker, this kind of speaker is called an inverted speaker. Since the sound radiated from the sound duct opening and the sound radiated forward from the speaker are superimposed in phase when reaching the front of the speaker, it can provide a wider frequency band than a closed speaker, and the radiation efficiency of the woofer unit is greatly improved. . In order to make the sound radiated by the sound duct opening in the playback frequency band exactly in phase with the sound radiated from the front of the loudspeaker, the parameter values of the loudspeaker used must be well selected and the loudspeaker carefully designed. Under ideal circumstances, the playback frequency should start from 80% of the speaker's lowest resonance frequency and spread out evenly and flatly to obtain a wide frequency range.
Inverted speakers can reproduce rich bass with a smaller cabinet, with less distortion and stable performance. It is currently the most widely used type, but its design and production are more complicated. In recent years, in order to broaden the bass replay frequency band, sound-absorbing materials have been filled in the sound tube, and a semi-enclosed box is made to control the phase inversion, so as to buffer some, and reduce the resonance frequency to achieve the purpose of broadening the bass replay frequency band. As a result, the inverter speaker becomes a semi-enclosed state, which is called a damped inverter speaker.
Also known as an inverted open-hole box, a low-frequency radiation speaker, is a type of speaker with an inverted hole (slot) on the speaker panel. Because of the holes, the sound inside the box can be radiated to the outside.
Inverted speakers, also known as low-frequency radiation speakers, are also the most commonly used cabinet design in multimedia speakers. The difference between it and the closed speaker is that the front of the speaker is designed with a cylindrical inverted hole to circulate the air inside and outside the box. It has a higher power capacity and lower distortion than a closed box, and the volume is sufficient. , High sensitivity, not only suitable for general households, but also for halls or professional places.
3 empty paper cone speakers
Also called passive bass radiating speaker or passive radiator, it is a new type of speaker system developed on the basis of an inverted speaker. It uses an empty paper cone to replace the sound tube in the phase-inverted speaker. It is composed of an ordinary speaker and an empty paper cone device installed in a closed box. The empty paper cone device is an ordinary speaker without the voice coil and magnetic circuit system. It is constructed with its paper cone and support system. At present, the empty paper cone device is often placed in the lower part of the speaker panel, so that not only the sound pressure in the mid and low frequency range is not easily affected by the floor, but the height of the speaker is also just right, so that the audio and video are positioned at the appropriate height. In addition, when the empty paper cone works in the super bass frequency range, the reflection of the floor can be used to improve the radiation efficiency, thereby further enhancing the bass effect.
The empty paper cone sound box utilizes the resonance formed by the air in the box and the mass of the vibration system (mainly the paper cone). The vibration of the speaker is then used to excite the empty paper cone through the air, and the corresponding vibration is made. From this point of view, it is similar to the resonance principle formed by the air quality in the sound duct and the air in the speaker, and it is very similar to the inverted speaker system. Their basic working process is also the same, all the backward radiated sound of the loudspeaker is in phase with the forward radiated sound after a certain device is inverted. However, in the subwoofer frequency range, the amplitude of the empty cone speaker is lower than that of the inverted speaker, and is closer to a closed speaker. That is, the empty cone speaker can effectively suppress the increase in the vibration amplitude of the speaker in the entire frequency band. The unstable sound reflected from the sound hole in the inverter speaker. The empty paper cone speaker also has the characteristics of relatively high replay frequency band sensitivity and easy installation.
4 Labyrinth speaker
This is a variation of the phase-inverted speaker. The structure is equipped with a sound tube made of sound-absorbing wall panels behind the speaker. The length of this tube is exactly half the wavelength of the low-frequency sound that needs to be raised. In this way, the opening of the tube The radiated sound is superimposed in phase with the forward radiated sound of the loudspeaker, so that the total radiated sound pressure is strengthened. However, when the length of the catheter is equal to a quarter of the wavelength, the situation is just the opposite, and an inverse resonance phenomenon will occur. Therefore, try to select this low-frequency lower limit value as the lowest resonance frequency of the speaker during design. In theory, the acoustic labyrinth speaker will attenuate the sound waves from behind the cone, preventing reflection to the open end and affecting the radiation of the woofer. In fact, it has a slight damping and tuning effect, which increases the sound output of the speaker near or below the resonance frequency, and can rapidly reduce the amplitude of the sound while enhancing the bass output.
Horn 5 (corner) speaker
There are forward horn (corner), back horn (corner) type, combined horn (corner) type and other types. The back of its cabinet is fully sealed, and the air pressure in the cabinet is added to the back of the speaker cone. In order to keep the front and back pressure balance of the cone, the horn (corner) device is generally placed in front of the speaker. The bass reproduction effect of the forward horn (corner) speaker is equivalent to a super-large sound reproduction system, and the back horn (corner) speaker is also called the reflection horn (corner) speaker. The speakers used can be directly seen in the structure. , And most of its horn (horn) is folded back. The combined horn (corner) type is a speaker form that combines a forward horn (corner) speaker and a folding horn (corner) speaker. The horn (corner) of the horn (corner) type sound box is generally made of wood materials, and the size of the horn (corner) opening depends on the cut-off frequency of the required radiation. If the truncation point frequency is low, the horn (horn) must have a larger caliber. The working principle of the horn (corner) cabinet is similar to that of the inverted speaker, but the low frequency response is not as good as the closed speaker and the inverted speaker, but its sound transmission efficiency is the highest, and it is mostly used in the hall and theater main amplification system And effect amplification system.
In addition, there are symmetrically driven speakers, Kelton speakers, acoustic matrix speakers, and multi-conductor speakers.