More than 100 years ago, on February 14, 1876, Alexander Graham Bell filed one of the most important patents in history, the "telephone". This invention allowed the human voice to travel farther than a shout. Humans also learned about the relationship between sound and electricity, and have been enjoying it ever since.
In order to better play back recorded sound, in 1910, S. G. Brown separated the driver from the diaphragm and invented the 'armature' armature headphones. In 1910, Baldwin invented the 'balanced armature'. The armature headphone is a U-shaped magnet with a movable iron plate (armature) in the middle, when the current flows through the coil, the armature will be magnetized and the magnet to produce the phenomenon of attraction and repulsion, and at the same time drive the diaphragm movement. This design was inexpensive and, although ineffective, was an epoch-making invention at the time, and the technology was mostly used in telephone handsets and small headphones.
In terms of sound-recording technology, Wente and Thuras designed the condenser microphone in 1917.
By the mid-1930s, the electrostatic loudspeaker, based on the principle of the condenser microphone, was introduced, and in the early 1950s the 'constant charge' law was proposed by C. V. Bocciarelli in the U.S.A. P. Walker independently developed the same theory during the same time period, applying it to the design of the famous Quad electrostatic loudspeaker. loudspeaker design.
The basic principle of the electrostatic loudspeaker is Coulomb's law, which is usually a plastic diaphragm with aluminum and other inductive materials vacuum vaporized, two diaphragms placed face to face, when one of them is added with a positive current high voltage, the other will induce a small current, by mutual attraction and exclusion of each other to promote the air will be able to emit sound. Electrostatic monomer due to the light weight and vibration dispersion is small, so electrostatic speakers work in the middle and high frequency bands, the sound quality is light and detailed, rich in character, it is easy to get clear and transparent middle and high sound. But its efficiency is not high, low sound pressure output, dynamic small, more expensive cost is also its weak point. In the same period as Bell, different loudspeaker types were proposed. As an amateur interest, Ernst W. Siemens (founder of Siemens & Halske) patented, on January 20, 1874, an electrodynamic loudspeaker prototype, in which a voice coil with a support system was placed in a magnetic field in order to keep the vibrating system in axial motion. At the time, it was used primarily in the relay rather than the loudspeaker field.
On December 14, 1877, Siemens patented the horn, which served as a sound radiator by attaching a parchment to the top of a moving voice coil, which could be made in the shape of an exponential cone; this was the first solid type of horn of the phonograph era.
In 1898, Oliver Lodge patented the first practical motorized loudspeaker, placing the voice coil in motion in a magnetic gap between an inner and outer circular pole plate, and like many inventions, at the time this great invention was too far ahead of its time. This invention determined the structure of 99% of modern moving coil speakers in 2014.
A full 25 years later, in the 1920s, radio broadcasting came along, and C. W. Rice and E. W. Kellogg published the groundbreaking paper 'A New Kind of Non-Horned Unit' detailing the direct radiating loudspeaker, and utilizing the theory to design the $250 Radiola 104 loudspeaker that took the U.S. by storm.
The basic principles of motorized loudspeakers have remained unchanged over the past fifty years, with only improved design details and components. Frequency response range dynamic range and other aspects of the old product has made great progress. Motorized speakers with simple structure, excellent sound quality, low cost, dynamic has become the mainstream of the market in 2014.
Motorized speakers are the most widely used, it is divided into paper cone, horn and dome three. Only the first two are introduced here.
1, paper cone speakers
Paper cone speakers are also known as moving coil speakers.
It consists of three parts: ① vibration system, including conical cone, voice coil and centering support piece, etc.; ② magnetic circuit system, including permanent magnet, magnetic plate and the field of core column, etc.; ③ auxiliary system, including the cone frame, junction plate, crimp and dust cover. When the voice coil in the magnetic field has audio current through, it produces a magnetic field that varies with the audio current, and this magnetic field interacts with the magnetic field of the permanent magnet, causing the voice coil to vibrate along the axial direction, due to the simple structure of the loudspeaker, full-bodied bass, soft sound quality, wide frequency band, but with lower efficiency.
2, horn-type speaker
The structure of the horn-type speaker, which consists of two parts of the vibration system (tweeter head) and the horn. Vibration system is similar to the paper cone speaker, the difference is that its diaphragm is not a paper cone, but a dome-shaped diaphragm. The vibration of the diaphragm radiates sound waves into the air through the horn (after two reflections). It has a high frequency and high volume, and is commonly used for outdoor and plaza sound reinforcement. During the period when the above loudspeaker technology was taking shape, it became clear that the ideal transducer should be a thin diaphragm that could pass an electric current, and the idea of a ribbon loudspeaker was conceived.
In January 1923, Schottky and Gerlach of Siemens Halske patented the first ribbon loudspeaker. It mounted a horizontally wavy pure-aluminum booklet membrane between the poles of a magnet. The wavy pure-aluminum membrane reduced the longitudinal stiffness and lowered the resonant frequency.
In 1931, Olson and Massa produced a ribbon microphone.
The ribbon loudspeaker is mainly used in the mid- to high-frequency range, where it is easy to form a linear source because of its flat frequency response curve and very high upper high-frequency limit, which has very good transient effects.
While the history of human electroacoustics is so convoluted and complex, there are indeed a very large number of excellent and innovative electroacoustic loudspeakers emerging today, and in fact, these innovative loudspeaker designs have left many of the best electroacoustic scientists of the last century scratching their heads. The horn (loudspeaker), generally known as the Horn of Africa, is an indispensable piece of equipment for a sound system. Everything from the "trumpet" for people to listen to music and enjoy it. Because of the quality of the electrical energy that goes into the "sound energy", the only equipment and the horn, the sound of the entire sound system, the characteristics play a decisive role.
Horn in the car appears more prominent sound system. In order to demonstrate a good tone and direction in the sense that a number of speakers and their layout is very important criteria. Speakers and effects: in the field of car audio, people have been pursuing such effects: in the car like to sit in front of the stage is that all the sound used in the windshield, hair, eyes, like the feeling of being at a concert. The sound of each instrument, you can achieve the best effect of playback. This is often called professional Hi-Fi (High Fidelity High Definition). The key to the ideal Hi-Fi effect is to synchronize the sound source and amplify the signal in the same frequency band. Home audio is not difficult. Since the home stereo frequency and high-mid units in the same fixed frame and all of the music signals are amplified by the same amplifier, the reduction ratio is consistent and relatively easy to achieve a good balance of sound quality. However, due to the limitations of different car audio installation locations, the woofer unit can usually only be installed in the luggage compartment, the bass general unit can only be installed in the front of the car, the tweeter is usually installed near the A-pillar. This effect may just come to listen to the treble and bass from the back to compare with the same month, Alto part is relatively weak. In addition, for different module and power amplification requirements, in a typical car stereo can only take multiple amplifiers to drive the speakers (many designs have a low frequency section that needs to be amplified by multiple amplifiers), so tonal balance is difficult to achieve at a satisfactory level. There are a number of factors involved in meeting these challenges, and the number of speakers and mounting arrangements is one of the keys. Number of speakers
Speaker volume can be determined by assigning the sound pointing to the fine, small roughness more. Advanced than the average number of car speakers speakers in the average vehicle. The installation position of the speakers often car stereo sound effect of the impact of speakers in different installation positions of the same two companies will have a different impact on the installation position of the speakers of the mid-advanced sedan stereo must be subjected to a variety of tests to determine it...
The number of speakers through the correct number of speakers with the right sound pointing fine. Through the number of speakers along with the correct installation experience and skills to cope with different bandwidth speakers installation position, maintain a good direction, compatible with the technology to adjust the power amplifier, and ultimately achieve good results. Installation layout has a direct impact on the Hi-Fi effect from a professional point of view, with an excellent balance of hi-fi sound quality through the front soundstage effect (sound effect feel front), the location of the soundstage (the impact of different sources in the field can be localized with precision), the spatial sense (about the spatial acoustic effect feel the bass response), the playback effect (reproduction of the hi-fi acoustic effect), (voice, tone and image quality) of the audiovisual effect, respectively. results) of the audiovisual effects, respectively. Good hydroacoustic localization (staging) depends to a large extent on the setup of the tweeter in front of the cab and the midrange unit setup around the cab. Because the human auditory system is mainly in the audio part of the sound wave arrives successively in the left and right ear rate sound source location. Nearby a tweeter and speaker installed in front of the door pillar only installed to achieve a coordinated and frequently matched midpoint can form a consistent, coordinated sound source. Taking into account the audience's left and right audio angle also depends on the position of the audio speakers, repeat the calculation to adjust precisely in order to make the car stereo to achieve a good sound field positioning. Therefore, for car stereo effect car speaker layout is very important. In 2014, the second session of the fair, Fudan University scientists said that they have successfully invented a square dance noise "stopping artifact" - active directional speakers.
Ordinary speakers emit sound is spread in all directions, to achieve orientation, the diameter of the speaker must be made very large. Different from the principle of traditional speakers, active directional speakers first low-frequency sound signals contained in a highly directional high-frequency signals on top, and then amplified, launched into the air, and then the air will be the high-frequency signals quickly filtered, the audible sound signals on it will be naturally filtered out, to achieve the directional propagation of the laser like.
Active directional speakers are able to control sound waves in a specific area, in which the sound waves are very strong, and out of this area, the sound waves will be very weak, or even none. If square dancers use this kind of speaker to play music, its nuisance 'embarrassment' can be solved." Ma Jianmin said. In addition to the square dance noise as a "forced to stop the magic weapon", active directional speakers can also be used in advertising exhibitions, waiting halls, bus stops and other scenarios, to realize the sound of a specific group of people directional broadcasting.
In 2014, the domestic market has not yet formed the product, the "magic weapon" is expected to be officially unveiled at the end of this year. Optimists believe that if a large number of market, this may be able to solve the plague of square dance noise nuisance problem. The speaker is always automatically deactivated in Win7
1, right-click on the "Computer" icon and select "Properties".
2, switch to the "Hardware" tab, select the sound card device in Device Manager, right-click to remove the device, find the menu bar operation, scan for changes, the system will pop up the sound card is installing the prompt, and so on for about 1 minute can be normal;
3, in addition, it may also be caused by the driver deactivation. It is recommended that you enter the device manager to find and right-click on the audio device, choose to uninstall, including the removal of the driver, and then scan the hardware to allow the system to install the driver itself.