In the past, many theaters used grid tops and pulley beams as the lower chords of the stage roof truss. This design and construction are relatively easy and can reduce some costs. However, because the construction personnel do not understand the technical parameters of the stage equipment, they suspend the equipment The installation, debugging and maintenance during use have caused great difficulties, and even affected the improvement of the stage art level, which is really worth the loss.
How to avoid damaging and burning speakers
The average person thinks that the loudspeaker will be unbearable if the volume is turned up too loudly, so the loudspeaker is broken. In fact, it is not the case. There are many kinds of situations that are possible, and there are wrong concepts. Now enumerate several situations and reasons separately, let you avoid the danger of speaker damage and burnout. First of all, we have to correct a wrong view. Many people think that the power of the power amplifier is greater than the power of the speaker, which will burn the speaker. This is wrong. But because the power of the power amplifier is less than the speaker, the speaker will be burned. This is because the waveform is distorted when the power is not enough, so that a DC component is generated. If the speaker is turned on and there is a sound and the cone is undulating, it means that there is a DC component. The voice coil with a DC component will heat up, which is why it burns. Some people may ask: What will happen to the speakers when the power of the amplifier is large? This is also a point to tell everyone. The volume gain must be well controlled. When debugging, the volume should not exceed the maximum value of the speaker, otherwise the speaker stroke will be too large when it is light, damage the speaker, and damage the cone when it is heavy. The crossover point of the treble must be accurate. If the crossover point is too low and there are low-frequency components, the treble will be heated and burned. No matter how high the treble is driven by the power amplifier, there must be a treble protection circuit to absorb the excess power. Otherwise, when the volume is too large, the transient current will be too large and it will burn the treble. Don't forget to increase the volume slowly from small to large, don't open it at a stretch. If the volume is too loud, it will be distorted and easily damage the speaker. Another situation is that the speaker will be damaged. It is recommended that users who prefer high volume should choose a high-power amplifier to feed the speaker power and work without distortion. If the power amplifier has a DC output, it will definitely burn out the woofer, and even a very small number of tweeters will burn out. The reason is that there is no capacitor in the splitting path of the bass (or other sound path) speaker to isolate DC. The DC output is like passing DC power into the speaker, and the burner coil is burnt black. Therefore, when purchasing an amplifier, be sure to measure whether the output of the front stage and the rear stage has a DC output with an electric meter. If the front stage has a DC output, it may also be passed to the speaker through the rear stage and then amplified. This also reminds everyone not to buy power amplifiers without quality assurance. In case you don't find this condition, you may burn out your advanced speakers.
Effect of speaker materials on sound
The speaker is basically composed of a driving unit, a crossover and a sound box. The design of these three parts is certainly important. The materials used are also closely related to the sound quality. If you change some of the materials and leave the rest unchanged, the sound will definitely be different. This The difference may be very obvious. Some enthusiasts who love to do it themselves try different materials to replace the original materials. For example, replacing the crossover with a "complement-grade" capacitor or replacing the original wiring with a fever cable. Some can improve the sound quality. Some disrupted the original sound balance. It is an elusive thing that the parts affect the sound quality. You think that replacing the supplement parts will improve the sound. Sometimes, on the contrary, the original parts are better with the sound quality or balance. This may have been achieved through careful experiment in design. The most ideal parts match. Enthusiasts can experiment by themselves, but once this happens, they will lose the warranty service of the agent. If you change the original parts arbitrarily, you are of course responsible for any problems.
Drive unit
The drive unit is commonly known as a horn. There are several points in the construction materials that deserve special attention. There are several materials for the diaphragm of the electric horn (medium and woofer diaphragm or sound cone). The paper diaphragm has a long history and its quality It is light and has proper damping characteristics. Many poultry manufacturers still insist on it, but the paper diaphragm is susceptible to moisture, mildew or deformation. Its surface hardness is low and it cannot produce high radiation speed. But it is very suitable for bass speakers with full and deep sound. Now paper diaphragms are mostly used on bass and midrange speakers, and the tweeters of paper diaphragms have almost disappeared.
In the early 1980s, plastic diaphragms began to appear. At the beginning, Bext used Bextrene on midrange and woofers. Later, polypropylene (Polypropylene) gradually became popular and became more popular. most. Polypropylene diaphragm has extremely high Yin-Yin characteristics, not affected by moisture, can be cast into any desired thickness and shape, light and hard, and has good physical properties and sound properties. Polypropylene can also be combined with other materials Mixed plastic casting into a harder diaphragm, such as mixed ceramic powder, glass fiber or graphite, has many changes. As for the fact that the sound of polypropylene diaphragm is better than that of paper, it is a matter of opinion. Manufacturers who use this material have a lot of opinions. It seems that there are only advantages but no disadvantages, but some people still think that the sound of the paper diaphragm is better, and the polypropylene has a "plastic" smell. In any case, the polypropylene material has been welcomed by manufacturers and users. It is not limited to use on midrange and woofer speakers, and tweeter diaphragms are also suitable.
Metal diaphragms have appeared in the 1980s, but the technology was only in its infancy, showing many shortcomings such as hard sound and high-pitched ears. Although the transient response is fast but the sound is unnatural, after years of improvement, The hemispherical metal diaphragm is the first to succeed. The materials include light metals such as aluminum, aluminum alloy and titanium. It will make use of its strengths and avoid shortcomings. In recent years, metal diaphragm hemispherical tweeters have become popular, even low-cost speakers.
As for the use of metal diaphragms for midrange and bass units to achieve excellent performance, it is still a matter of recent years. British AE (AcousTIc Energy) first made all-metal diaphragm speakers, which received high praise but were expensive. After AE, Monitor Audio has also developed into an all-metal diaphragm speaker, taking this technology to a more mature stage. The advantages of the all-metal diaphragm speaker are fast sound, clean and tidy, particularly high treble and high transparency.
There is a ring of edges around the diaphragm connected to the moving frame. It is a compliant material that provides free movement suspension for the diaphragm. There are many materials used, including natural rubber, artificial rubber, PVC plastic. The varnished cloths are made into wavy or half-curled dishes, so that the flexibility reaches the specified level. The edge of the woofer of the air cushion speaker must have a very high flexibility on the face to facilitate large movements. Generally speaking, the ventilated speakers What is needed is lower edge compliance, which is the main reason for considering which material to use.
support
The job of the speaker bracket is to maintain the mechanical structure stability and provide accurate movement for the diaphragm. The bracket must be structurally strong and avoid resonance. Generally, the bracket material used for the speaker is steel, aluminum alloy or magnesium alloy. The steel bracket is made of high pressure. If the steel material is thick, it is also quite strong. Nowadays, many large-diameter woofers still use steel brackets. However, if the steel material is too thin, it will easily cause resonance. The steel bracket is relatively cheap to manufacture, so it is generally used in low-cost speakers.
Aluminum or magnesium alloy die-cast brackets have better performance in terms of robustness and anti-resonance, and their appearance is more beautiful and expensive, but the manufacturing cost of such brackets is higher than that of steel frames. Some speakers are especially Japanese products, although the price is not expensive, but also use alloy die-casting brackets, mainly to make the appearance more attractive, in fact, the quality of the speakers is mediocre.
Voice coil
The voice coil of the speaker is different according to the needs of the low, medium and high tweeters. The voice coil of the tweeter is formed by very thin wires, including copper wire and aluminum wire. The aluminum wire is lighter and lighter, which can obtain better instantaneous sound. Response, but not as good as copper wire in terms of carrying capacity and durability. Midrange and woofers use copper wire around the voice coil, and the copper wire is thicker to withstand high power. Some woofers are wound around the second to fourth layer voice coil to increase the bearing capacity As for the shape of copper wire is also different, such as round, hexagonal and rectangular cross-section, round wire is the most commonly used, hexagonal and rectangular wire can be closely arranged without leaving a gap, which can increase the heat dissipation efficiency and increase the power carrying capacity.
The voice coils of ordinary speakers are mostly wound on the paper tube, but paper is not a good thermal conductor, but only has the advantage of lightness. In order to improve the heat dissipation efficiency, some speakers use aluminum or Kapton voice coil tubes to fix the voice coil on the tube due to heat dissipation. Preferably, the bearing capacity is significantly increased. Recently, more and more speakers use this material.
Most burned speakers usually occur on tweeters. Because their voice coils are wound with thin wires, they cannot withstand high power. Some speakers are equipped with protection circuits. When the input current is too high, the current is automatically cut off or reduced to prevent damage to the tweeter. The midrange and woofer voice coils are strong and not easy to burn out. Only when the input is too strong may the voice coil hit the bottom or be skewed.
magnet
Early speakers mostly used magnesium-nickel-cobalt (Alinco) alloy magnets, which have the advantages of high strength and easy to prevent magnetic field stagnation. Unfortunately, the manufacturing cost is getting higher and higher. Manufacturers are forced to use iron oxide magnets, also known as ceramic magnets. It also has a very high magnetic force, but it needs to use a large piece. Some woofer magnets weigh 20 to 30 pounds, and the magnetic field has strong dissemination. It must be carefully controlled when used in flood control magnetic places.
There is a rare earth magnet called Samarium Cobalt, the Chinese name is translated as samarium cobalt magnet, its magnetic force is five to six times that of traditional magnet, so only a small amount can achieve sufficient strength, this kind of magnet is very expensive, compare It is suitable for high unit, rare in midrange and bass unit.
Crossover
The splitter is usually composed of three parts, including inductance coil, capacitor and resistance. The coil is wound with copper wire. The high-pass part is thinner and the low-pass part is thicker. The coil of the crossover has air core and iron. Core style, depending on different designs. Capacitors have a great influence on the sound quality. Nowadays, the condensers of high-quality speakers mostly use polypropylene capacitors, and its quality is highly concerned by HI FI fans.
Generally, the speaker of the speaker usually installs the parts on the circuit board, which is neat and beautiful, but the copper traces of the circuit board may be unfavorable for the high current mark due to the narrow path relationship. Therefore, some audiophile speakers use direct hard wire welding to obtain Better sound quality.
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