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The Construction and Principle Analysis of Headphones

?A headset is mainly composed of four parts: headband, left and right sound unit, ear and lead. The function of the headband is to fix the left and right sounding units, place it on both sides of the head, its structure and its connection with the unit determines the headband and earmuffs on the head of the pressure, affecting the headset wearing comfort. Earmuffs are part of the head that is in contact with the sound unit. It is essential for moving headphones, and its function beats by dr dre is to reflect the low frequency back to ensure low frequency playback. Earmuffs generally have two styles, one beats headphones on sale on the ear, called Supra-aural, and the other is cup-shaped, surrounded by ears, called Circumna. Earmuffs should be as soft and comfortable as possible, and its interior is usually filled with sponge, covered with leather or flannel. The materials used in the earmuffs absorb the intermediate frequency and high frequency, which make the ear form a distance from the diaphragm and form a chamber between the headphones and the head. Large around the ears of the internal space of the earmuffs, the sound can act on the auricle, the formation of a better sense of space. A well-designed headset has been fully considered the role of the earmuffs, so the high-end headphones can not be damaged or free replacement.

The headphone cable is the headphone amplifier circuit output and the earphone voice coil connection line, high-quality headphone cable often use multi-core core oxygen-free copper (OFC) line, through strict insulation and shielding treatment, to prevent copper impurities in the signal transmission Influence and external clutter interference. The end of the headphone cable is plug, there are two specifications: 6.35mm and 3.5mm, that is usually the size of the plug, 6.35mm plug for professional audio and civilian audio equipment, 3.5mm plug for portable devices. General high-fidelity earphones will provide plug-in converter, to ensure that the headset in a variety of equipment on the use. In the high-end headset plug is gold-plated, this is not for the beautiful, mainly to prevent the oxidation of the plug sound, because the gold is smooth and soft, can also provide as much contact area as possible. Low-end headphones often use nickel-plated plug, so that although it can also prevent oxidation, the sound has a certain negative impact. Headset sound unit is the most complex headset design, the highest technical content of the part. The working principle of the moving headphone is the same as that of the moving loudspeaker. After the audio signal is input into the voice coil, the electromagnetic field generated by the voice coil changes with the change of the signal. The electromagnetic field interacts with the magnetic circuit to push the movement of the voice coil and diaphragm. Push the air to sound. The headphones are composed of three parts: magnetic circuit system, vibration system, cavity and hole and other acoustic structure.

The magnetic circuit system consists of constant magnets, beats solo plates and pole pieces, which have a direct effect on the performance and reliability of the headphones. One side of the permanent magnets is the flat plate type plate and the other side is the "T" The plate and the pole piece form a smaller annular magnetic gap, and the voice coil of the vibration system is suspended in the gap. Usually high-fidelity headphones using high-performance magnets for the excellent performance of neodymium ferromagnet, the earlier headset models have the use of expensive samarium cobalt magnets, low-end headphones generally use ferrite. Magnetic circuit system design is more complex, high-end headphones its magnetic circuit using a computer-aided design. The production process of the magnetic circuit is also an aspect of its performance. Design and manufacture of excellent magnetic circuit system can effectively control the vibration system, get a higher sensitivity, smaller distortion, good transient and low frequency.

The vibration system consists of voice coil and diaphragm. The diaphragm is an acoustic radiation element that promotes air vibration and directly affects the frequency response and sensitivity. Its performance depends primarily on the manufacture of materials, shapes and manufacturing processes. The material of the diaphragm is required to be as small as possible per unit area, with high mechanical strength and large damping. The higher the mechanical strength, the more efficient the wider the frequency range, the higher the output sound pressure level; the greater the damping, the large signal distortion. Now the diaphragm is easy to use thermoforming, light weight, good rigidity of polyester film, some companies have developed a new material for the diaphragm, the company separated from the acetic acid bacteria in the cellulose produced "biological diaphragm" For its high-level headphones and earplugs, high frequency is very excellent. The diaphragm is usually round, the center of the design for the convex arc-shaped, surrounded by the design of the ribs, can strengthen the diaphragm stiffness and increase the effective area of ??the diaphragm. Sometimes for the purpose of air pressure balance, a small hole is machined in the non-vibrating part of the diaphragm. Diaphragm manufacturing on the process requirements are very high, in the processing of a variety of differential control very strict.

The voice coil is the vibration source of the moving headphones, and most of the headphones, such as impedance, sensitivity, rated power, are related to it. The performance of the voice coil depends mainly on the number of turns of the material and voice coil used, that is, the length of the voice coil. Voice coil material is generally copper enameled wire, advanced headphones often use oxygen-free copper enameled wire and copper clad aluminum enameled wire, which has the advantages of copper enameled wire, but the quality is lighter, there are silver as the voice coil material. Voice coil enameled wire cross section is mostly round, there are triangular and hexagonal cross-section, so the line between the more closely, the line between the capacitor to reduce the voice coil to further reduce the quality. The size of the voice coil on the headset performance also have a certain impact. The voice coil is vibrated in the magnetic gap, its diameter should ensure that the voice coil is located in the middle of the magnetic gap, in the vibration will not touch with the pole and pole pieces. On the other hand, since the magnetic field at the surface of the electrode plate is not uniform, the movement of the coil in the non-uniform magnetic field will reduce the conversion efficiency of the electro-acoustic energy and cause distortion of the headphones. Therefore, An appropriate choice. Cavity and hole and other acoustic structure is an important part of the performance of the headset. Fixed magnetic circuit system and vibration system is a plastic frame, called the table, the edge of the diaphragm to adhere to the frame. This frame should be rigid enough not to deform due to fixed magnetic and vibrating parts, and to minimize vibration. Magnetic circuit and vibration system is behind the headphone shell, shell and the table to form a cavity between the cavity of the size, shape, the internal filling of the damping material location, type, the beats by dre wireless number of headphones affect the frequency response, The bigger the body, the easier it is to get high quality, deep potential low frequencies.