Speaker is basically composed of a driver unit, a splitter, and a sound box. The design of these three parts is important, and the materials used are closely related to the sound quality. If some of the materials are changed and the rest remain unchanged, the sound will inevitably differ. This difference may be very obvious. Some audiophiles who love to do it themselves try different materials to replace the original materials, such as replacing the splitter with a "supplement grade" capacitor or replacing the original wiring with a fever wire. Some can improve the sound quality, while others can destroy the original sound balance. The impact of parts on sound quality is an unpredictable thing. You may think that replacing replacement parts will improve the sound, but sometimes the opposite is true. The original combination of several parts may have better sound quality or balance, which may be due to careful experimentation during design to achieve the most ideal part combination. Audiophiles can conduct experiments themselves, but once they do, they will lose the warranty service provided by the agent. If you make any changes to the original parts, you will be responsible for any problems that arise. So in the public broadcasting system, it is best for customers not to make arbitrary changes to the products provided by manufacturers, otherwise it may cause trouble for themselves
Drive unit
The drive unit, commonly known as a speaker, has several materials that deserve special attention in terms of construction. There are several materials for the diaphragm of electric speakers (also known as the diaphragm or soundstage of mid and low frequency speakers). Paper diaphragm has a long history and is chosen for its light weight and appropriate damping characteristics. Many famous factories still insist on using it, but paper diaphragm is prone to moisture, mold, or deformation. Its surface hardness is low and cannot produce high radiation sound wave velocity. But it is very suitable for bass speakers with rich and deep sound. Nowadays, paper diaphragms are mostly used in low-frequency and mid-range speakers, and high-frequency speakers with paper diaphragms have almost disappeared.
In the early 1980s, plastic diaphragms began to appear. Initially, the BBC used Bextrene for mid-range and subwoofers, and later polypropylene became increasingly common and popular. Today, a large proportion of speakers use this material. Polypropylene diaphragm has extremely high dielectric properties and is not affected by moisture. It can be molded into any desired thickness and shape, with light and hard weight and excellent physical and acoustic properties. Polypropylene can also be mixed with other materials to mold higher hardness diaphragms, such as mixed ceramic powder, glass fiber, or graphite, with many variations. As for whether polypropylene diaphragm is actually better than paper diaphragm, it varies from person to person. Manufacturers who use this material boast about its advantages without any disadvantages, but some people still believe that paper diaphragm has better sound and polypropylene has a "plastic" flavor. Anyway, polypropylene material has been well received by manufacturers and users, and it is not limited to use in mid-range and low-frequency speakers. High frequency speaker diaphragms are also suitable.
Metal diaphragms appeared in the 1980s, but at that time the technology was only in its early stages and revealed many drawbacks, such as dry and hard sound, ear piercing high notes, and unnatural sound despite fast transient response. After years of improvement, the hemispherical metal diaphragm of the high-frequency unit was the first to achieve success, using materials such as aluminum, aluminum alloy, and titanium to leverage its strengths and avoid its drawbacks. In recent years, metal diaphragm hemispherical high-frequency units have become popular, and even low-priced speakers have adopted them.
As for the use of metal diaphragms to achieve excellent performance in the mid-range and bass units, it has only been a few years. AE (Acoustic Energy) in the UK was the first to produce all metal diaphragm speakers, which received high praise but were expensive in price. After AE, Monitor Audio has also developed full metal diaphragm speakers, taking this technology to a more mature stage. The advantages of all metal diaphragm speakers are fast sound speed, clean and sharp sound, particularly wide and high pitched sound, and high transparency.
There is a circle of edges around the diaphragm connected to the moving frame. It is a flexible material that provides free movement suspension for the diaphragm. There are various materials used, including natural rubber, synthetic rubber, PVC plastic. In the early days, some manufacturers used cloth with paint film, which was made into a wavy or semi rolled edge to achieve the specified level of flexibility. The low-frequency speaker edge of air cushion speakers must have very high flexibility for large range of movement. Generally, breathable speakers require low edge flexibility, which is the main reason for considering which material to use.
Bracket
The job of the horn bracket is to maintain mechanical structural stability and provide accurate movement for the diaphragm. The bracket must be constructed firmly and avoid resonance. Generally, the bracket materials used for horns include steel, aluminum alloy, magnesium alloy, etc. The steel bracket is made of high pressure, and if the steel material is thick, it is also quite strong. Nowadays, many large-diameter subwoofers still use steel brackets, but if the steel material is too thin, it is easy to cause resonance. The manufacturing cost of steel brackets is relatively low, so they are widely used in low-priced speakers.
Aluminum or magnesium alloy die cast brackets have better durability and anti resonance performance, and are also more aesthetically pleasing and expensive in appearance. However, the manufacturing cost of such brackets is higher than that of steel frames. Some speakers, especially those made in Japan, although not expensive, also use alloy die-casting brackets mainly to make the appearance more attractive. In fact, the quality of the speakers is mediocre.
voice coil
Speaker voice coils vary according to the needs of low, medium, and high frequency units. High frequency speaker voice coils are wound with very thin wires, including copper wire and aluminum wire. Aluminum wire is lighter in weight and can achieve better transient response, but its load-bearing capacity and durability are not as good as copper wire. Medium and low frequency speakers often use copper wire to wrap the voice coil, and the copper wire is thicker and can withstand high power. Some low frequency speakers wrap two to four layers of voice coils to increase load-bearing capacity. As for the shape of copper wire, such as circular, hexagonal, and rectangular cross-sections, circular wire is the most commonly used, while hexagonal and rectangular wires can be tightly arranged without gaps, which can increase heat dissipation efficiency and correspondingly improve power carrying capacity.
The voice coil of ordinary speakers is often wound around a paper tube, but paper is not a good thermal conductor and only has the advantage of being lightweight. In order to improve heat dissipation efficiency, some speakers use aluminum or Kapton voice coil tubes, which fix the voice coil on the tube for better heat dissipation and significantly increase the load-bearing capacity. Recently, more and more speakers are using this material.
Generally, burning of speakers occurs mostly on high pitched speakers because their voice coils are wound with thin wires and cannot withstand high power. Some speakers are equipped with protective circuits that automatically cut off or reduce the current when the input current is too high to prevent damage to the high pitched speakers. Mid and low frequency speakers have robust voice coils that are less prone to burning out. However, when the input is too strong, it may cause the voice coil to hit the bottom or tilt.
magnet
Early speakers often used magnesium nickel cobalt (Alinco) alloy magnets, which have the advantages of high strength and easy prevention of magnetic field leakage. Unfortunately, manufacturing costs have become increasingly high, and manufacturers have been forced to use iron oxide magnets, also known as ceramic magnets, which also have considerable magnetic force but require large pieces. Some subwoofer magnets weigh 20 to 30 pounds and have strong magnetic field dispersion. They must be carefully controlled when used in flood resistant magnetic areas.
There is a rare type of magnet on Earth called Samarium Cobalt, which is translated as samarium cobalt magnet in Chinese. Its magnetic force is five to six times that of traditional magnets, so only a small amount is needed to achieve sufficient strength. This type of magnet is very expensive and is more suitable for use in high frequency units, but rarely seen in mid frequency and low frequency units.
Splitter
A splitter is usually composed of three types of components, including an inductor coil, a capacitor, and a resistor. The coil is wound with copper wire, and the high pass wire is thinner while the low-pass wire is thicker. The coil of the splitter can be air core or iron core, depending on different designs. Capacitors have a significant impact on sound quality. Nowadays, high-quality speakers often use polypropylene capacitors in their splitters, and their quality is highly valued by HI FI fans.
Generally, the sound scanner of a speaker is installed with components on the circuit board, which is neat and beautiful. However, the copper traces on the circuit board may be unfavorable for high current markings due to the narrow path. Therefore, some high-end speakers use direct hard wire soldering to achieve better sound quality.
Sound box
The main requirement for the sound box material of a speaker is to have good damping characteristics, be sturdy and resonance free. In order to achieve this goal, designers have used various materials in the past, including particleboard, plywood, fiberboard, plastic, and even artificial marble, concrete, and metal. Generally, soundboxes are often made of wood plywood or crushed wood particle plywood, which are easy to cut and manufacture. Nowadays, many high-end speakers use medium density fiberboard (MDF), which has better characteristics. Celestion pioneered the use of aviation technology in their SL600 bookshelf speaker, which features a three layered aluminum sound box that is as sturdy and resonant as an airplane floor. The bookshelf speaker is highly successful. Another innovative sound box structure is B&W's Matrix, which features a skeleton like structure combined with sound-absorbing latex to achieve pure sound quality
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