The trumpet is divided into several different musical instruments, a kind of wind instrument, with thin upper part and thick lower part, mostly made of copper. The other is a modern electro-acoustic component, whose function is to convert electrical signals into sound, also called speakers. It can also be used to describe someone who advocates and promotes for others.
A horn is actually a conversion device that converts electrical energy into sound. When different electronic energy is transmitted to the coil, the coil generates a kind of energy to interact with the magnetic field of the magnet. This interaction causes the paper plate to vibrate because the electronic energy changes at any time. The coil of the horn will move forward or backward, so the paper tray of the horn will follow it. This action changes the density of the air and produces sound.
Horn sound modeMoving coil
The basic principle comes from Fleming’s left-hand law. Put a current-carrying wire perpendicular to the magnetic field line between the north and south poles of the magnet, and the wire will be moved by the interaction of the magnetic field line and the current. A diaphragm is attached to this one. On the track, the diaphragm will move back and forth as the current changes. At present, more than 90% of cones are of moving coil design.
Electromagnetic
A movable iron chopping piece (armature) is installed in the middle of a U-shaped magnet. When the current flows through the coil, the armature will be magnetized and repelled by the magnet, and at the same time drive the diaphragm to move. This kind of design is low cost but not effective, so it is mostly used in telephone receivers and small earphones.
Inductive
Similar to the electromagnetic principle, but the armature is doubled, and the two voice coils on the magnet are not symmetrical. When the signal current passes through, the two armatures will push each other for different magnetic fluxes and move. The difference from electromagnetic is that inductance can regenerate lower frequencies, but the efficiency is very low.
Electrostatic
The basic principle is Coulomb's law, which is usually based on the vacuum vaporization of a plastic diaphragm with inductive materials such as aluminum. The two diaphragms are placed face-to-face, and when one of them is applied with a positive current and high voltage, the other will sense With a small current, the air can be driven by mutual attraction and repulsion to produce sound. Because of its light weight and low vibration dispersion, the electrostatic monomer is easy to get a clear and transparent mid- to high-frequency sound, and it is not able to grasp the bass power, and its efficiency is not high, and it is easy to gather dust when using a direct current generator. At present, manufacturers such as Martin-Logan have successfully developed static and dynamic hybrid speakers, which solves the problem of insufficient bass bass of the static body. The static type is also widely used in headphones.
Flat
The first design developed by SONY of Japan, the voice coil design is still the theme of the moving coil, but the cone diaphragm is changed to a honeycomb structure flat diaphragm, because of the small number of people and the hollow effect, the characteristics are better, but the efficiency is also low. .
Ribbon
There is no traditional voice coil design, the diaphragm is made of very thin metal, and the current flows directly into the channel body to make it vibrate. Because its diaphragm is a voice coil, it has very light weight, excellent transient response, and high frequency response. However, the efficiency and low impedance of the ribbon speaker have always been a big challenge to the amplifier, and Apogee can be a representative. Another way is to have a voice coil, but the voice coil is printed directly on the plastic sheet, which can solve some of the problem of low impedance. Magnepang is the leader of such designs.
Horn pose
The diaphragm pushes the air at the bottom of the horn to work. Because the sound is not diffused during transmission, the efficiency is very high. However, because the shape and length of the horn will affect the tone, it is not easy to replay low frequencies. Now it is mostly used in giant PA systems or In terms of the tweeter, Klipsch is a long-established manufacturer of horn speakers.
other
There is also a ribbon-like improved design developed by Dr. Haier in 1973, called the Haier horn, which is excellent in theory, but Taiwanese users are rare. Piezoelectric is a design that uses piezoelectric materials such as titanic acid to expand or contract by applying voltage. Pioneer has improved the piezoelectric design with high polymers and used them on their tweeters. Ion horn (Ion) uses high-voltage discharge to make air become a charged substance. After an AC voltage is applied, these free charged molecules will produce 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), which is equipped with an active feedback circuit in the speaker, which can greatly reduce distortion.
1. If the horn is overloaded for a long time, the horn will be burnt out due to overheating. The temperature of the coil will rise, causing some structural parts to melt, crack or burn. The temperature of the coil will be 180 degrees Celsius under normal use. You can imagine it under normal use!
2. Mechanical failure, the overloaded driving horn causes the paper tray to move beyond the range and separate from the coil, or the coil and the coil base are separated, the paper tray is folded or the horn support ring is torn. Once any of the above situations occurs, all Can cause the speaker to malfunction. When the folded edge or the support ring is torn, the coil will rub against them, because the paper tray assembly can no longer be properly suspended in the center position, small cracks may not be felt at first, but after a period of time, when the cracks become larger At times, the horn will be broken.
3. The failure of the horn may also be a combination of the above two methods. For example, the power amplifier suddenly outputs a large instantaneous energy. This energy can be that the sound suddenly turns on, and the horn will vibrate strongly, causing the coil to leave the magnetic gap. , When it goes back, it may be eccentric and fail to return to its original position. This will cause the entire mechanical movement to be taken forward by the paper tray and deviate from the original position. As a result, the paper tray can no longer emit sound, but the energy continues to be transmitted. On the coil of the horn, the coil has left the magnetic gap, because the magnetic gap is the best heat dissipation environment for the coil, but the coil has left the magnetic gap, then when the coil continues to receive the signal from the power amplifier, the coil will quickly heat up and burn the coil. . But this kind of situation is relatively rare now, because the current horns are all long-stroke designs.
Speaker sizeMost people use a metric ruler. Measure the number of centimeters behind the diameter of the paper cone and divide it by 2.54 (2.54 centimeters equals one inch) to get inches.
4 inch speaker: the diagonal distance of screw holes is 11.5 cm, the distance between adjacent holes is 8 cm, and the horn diameter is 10 cm;
5-inch speaker: The diagonal distance of screw holes is 13.5 cm, the distance between adjacent holes is 9.5 cm, and the diameter is 13 cm;
6.5-inch speaker: the diagonal distance of screw holes is 15.5 cm, the distance between adjacent holes is 11 cm, and the diameter is 16.5 cm;
The distance between 4X6 inch adjacent screw holes is 12.3 cm and 7.3 cm;
The distance between adjacent screw holes of 6X9 inches is 16.5 cm and 11 cm respectively.
The structure of the horn1. Folding ring (leather edge). Its function is to provide a certain degree of compliance for the movement of the cone, that is, to have a certain degree of flexibility, so that the cone can move back and forth, and there are auxiliary elastic waves to position the cone together to keep the voice coil in the center of the magnetic gap. And provide the role of restoring force of cone movement.
2. Cone cone (drum paper, diaphragm, paper cone). It is the main sounding component of the horn. It directly drives the air, and converts the mechanical movement of the unit into the sound wave transmission movement of the air.
3. Dust cover. Prevent foreign objects from falling into the magnetic gap and affecting the movement of the voice coil.
4. Bouncing (centering support piece). The function is mainly to provide restoring force for the movement of the cone and to keep the voice coil in the correct position in the magnetic gap during movement.
5. Basin stand. It is the skeleton of the entire speaker unit, and most of the components are directly or indirectly fixed on the frame. But its impact on sound is relatively small.
6. Voice coil and voice coil skeleton. The voice coil is the central component of the horn unit's sound. The horn completes the conversion from electrical energy to mechanical energy by relying on the voice coil.
7. Washer (splint), T iron (permeable plate column, electrical iron). It is generally made of low carbon steel or pure iron and requires high magnetic permeability. The main characteristic is magnetic permeability, but there is no remanence, even after the magnetic field disappears, its magnetism disappears immediately. Together with the magnet, they form the magnetic circuit system of the unit.
8. Magnetic cylinder (magnet). Before the speaker is assembled, it is non-magnetic. After it is glued to the T-iron splint with an adhesive, it is magnetized on the magnetizer. The final residual magnetism is the magnetism of the magnetic steel. The magnet types of the speaker unit mainly include ferrite, There are three major categories of neodymium iron boron and aluminum nickel cobalt.
First put the multimeter in the resistance position, and put the red and black test pens of the multimeter on the two pins of the speaker. If the measured resistance value is equal to zero or very small, it means that there is a short circuit inside the coil of the speaker; if the measured resistance value is Hit the infinity position, indicating that the speaker is broken.
The normal resistance value of a general speaker is 4, 8, 12 or 16 ohms.
Set the analog multimeter to the DC 0～5mA block, and then connect the two test leads to the two solder tabs of the speaker. Lightly press the paper cone of the speaker and observe the swing direction of the pointer of the multimeter. If the pointer is deflected in the positive direction, the red test lead is connected to the negative pole of the speaker, and the black test lead is connected to the positive pole of the speaker. On the contrary, the red test lead is connected to the positive electrode, and the black test lead is connected to the negative electrode.
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