What is the principle of horn sounding?

As early as 1877, Erenst Vemer of Siemens, Germany, obtained the patent for the dynamic speaker, but the vacuum tube was not officially used until 1907, and Edison's earliest phonograph was that the stylus directly drove the diaphragm and then amplified the sound through the speaker, so the patent of Siemens has never been used. It was not until 1920 that Chester Rice, Edward Kellogg and Edison Bell ·P·g· Hokuto of American Singular Company developed the practical power horn for the first time. In the past 70 years, besides the continuous improvement of materials, do you remember that the horn technology has really improved? The following are several common speaker sounding methods:

First, the moving coil type. The basic principle comes from Fleming's left hand law. A current trajectory perpendicular to the magnetic field lines is placed between the north and south poles of the magnet, and the trajectory will move due to the interaction between the magnetic field lines and the current. When a diaphragm is attached to this track, it will move back and forth with the change of current. At present, more than 90% of cone-basin monomers are designed in moving coils.

Second, electromagnetism. A movable iron anvil (armature) stands in the middle of the U-shaped magnet. When current flows through the coil, the armature will be magnetized, the magnet will attract and repel, and at the same time drive the diaphragm to move. This design is low in cost but not effective, so it is often used in telephones and small headphones.

Third, inductive. Similar to the electromagnetic principle, but the armature is doubled and the two voice coils on the magnet are asymmetrical. When the signal current passes through, the two armatures will push each other because of different magnetic fluxes. Unlike electromagnetism, inductance can regenerate lower frequency, but its efficiency is very low.

Fourth, electrostatic type. The basic principle is Coulomb's law, which is usually treated by vacuum evaporation of induction materials such as plastic diaphragm and aluminum. The two diaphragms are placed face to face. When positive current and high voltage are applied to one of them, the other will induce a small current, which can make the air sound through mutual attraction and repulsion. Electrostatic monomer has light weight, small vibration dispersion, easy to get clear and transparent medium and high notes, low efficiency, and easy to accumulate dust when using DC power supply. At present, Martin-Logan and other manufacturers have successfully developed a hybrid speaker with static and electric coils, which solves the problem of insufficient static bass, and static electricity is also widely used in headphones.

5. Plane style. The first design developed by Sony in Japan, the theme of voice coil design is still moving coil, but the cone-basin diaphragm is changed into a flat diaphragm with honeycomb structure, which has better characteristics but lower efficiency because of the small cavity effect.

Sixth, ribbon style. Without the traditional voice coil design, the diaphragm is made of very thin metal, and the current flows directly into the channel to make it vibrate and sound. Because its diaphragm is a voice coil, it is very light in weight and has excellent transient response and good high frequency response. However, the efficiency and low impedance of the strip horn have always been a great challenge to the expander, and apogee can be represented. Another way is to have a voice coil, but printing the voice coil directly on the plastic sheet can solve some low impedance problems. Magnepang is a leader in this kind of design.

Seven, trumpet type. The diaphragm pushes the air at the bottom of the horn to work. Because the sound does not spread during transmission, the efficiency is high. However, because the shape and length of the horn will affect the timbre, it is not easy to reproduce the low frequency. Now it is mainly used for giant public address systems or tweeters.

Klipsch in America is an old-fashioned speaker manufacturer.

Eight, there is an improved ribbon design developed by Dr. Haier in 1973, called ear horn. Excellent in theory, but few users in Taiwan Province province. Piezoelectric type is a design that uses piezoelectric materials such as titanic acid and voltage to make it expand and contract. Pioneers use polymers to improve piezoelectric design and use them in their high-pitched monomers. Ion horn (ion) uses high voltage discharge to charge air. When an alternating voltage is applied, these freely charged molecules will sound due to vibration. At present, it can only be used in monomers above high frequency.

Philips has also developed an active feedback speaker (MFB), in which an active feedback circuit is installed, which can greatly reduce distortion. These designs are not mainstream at present, so we will discuss them again when we have the opportunity.