The front baffle of the structure is made of strong medium density wood fiberboard with a thickness of 5 cm.
In fact, the whole loudspeaker can be regarded as a center for converting electric energy into sound. Its function includes that air molecules vibrate under the electromagnetic induction of the voice coil coupled with the diaphragm, and then after exciting the voice coil (wrapped in a magnetic field), the micro-current corresponding to music information can move back and forth according to the music rhythm, so that the current energy is converted into sound energy. Theoretically, this is only a basic principle, but in practice, in order to approach the original signal as close as possible after energy conversion, it is particularly important to fix the diaphragm motion perfectly with reference. When the diaphragm moves, the single frame must not vibrate, its acceleration must be zero, and a completely inert mechanical structure benchmark must be formed.
A single frame is tightly fixed on the front sound insulation board of the loudspeaker, and the mass ratio of the freely moving parts (voice coil and diaphragm) to the structure (frame and front sound insulation board) must be as high as possible, which is the application of the basic principle of dynamic range: f = Mr "r" acceleration is equal to the movement of the cone divided by the mass of the frame, and the ideal value must be zero, so the mass "m" must be as high as possible, and infinite weight is the ultimate goal. Therefore, from the point of view of rigidity, no matter what material is used for the front baffle, problems will occur if the quality characteristics are ignored. You should be able to simply imagine that the front baffle with high damping coefficient can avoid the vibration caused by feedback effect, but at the expense of power output. Only high quality can ensure excellent transient response, and damping can never replace quality characteristics.
The internal reinforcement structure improves the strength of the speaker, and the internal damping is composed of double layers of different materials.
The optimized structure provides a good guide for the sound cone, forming a piston-like movement, which is not disturbed by the echo turbulence.
The bass frequency domain usually has strong kinetic energy, and the bass monomer will cause the vibration of the front baffle of the speaker, and then interfere with the interactive modulation of the midrange and treble monomer, especially the treble monomer with very small vibration amplitude of the diaphragm, and the details will be lost. The best solution is to accurately construct the complex process of locking the speaker structure with the single body.
The "R" front baffle used in Electra series has the following dual characteristics:
Inertia is the real playback of low-frequency transient output, maintaining an indispensable shock.
Suppress the vibration of the front sound insulation board, which will lead to the reproduction of sound dyeing in the middle and high frequency domain.
Using solid density wood fiber board with a thickness of five centimeters, Electra series ultra-high quality front baffle has the above two characteristics; This means that the "R" acceleration of the structure is almost equal to zero, so any derived vibration can be avoided. The mass ratio of Electra series cone and voice coil is much more than five times that of general products.
The five-centimeter-thick structure on the back also has a decisive advantage. When you think about it, it provides substantial sound wave guidance for the echo of the bass unit. If introduced, the diaphragm moves like a piston, and when the sound wave reflects the impact in the box, it will not be distorted or hindered by the twisting or rolling action. When the operation is ideal, the reproduction of the bass unit will not be affected by the distortion from the mechanical limitation.
These efforts are aimed at eliminating various vibration sources to create excellent low-audio dynamic response. Also, because the sound dyeing problem of the box is completely suppressed, the audio and video are clearer, the timbre is more accurate, and the clarity and permeability in the middle and high frequency domain are better, just like the wonderful detail interpretation without any masking effect. The revolutionary diaphragm shape was originally designed for Utopia series, and now Electra series also uses the same monomer.
A single diaphragm must have three extremely important characteristics:
1, with high rigidity, enables the cone to move like a piston in a wide range, especially with low frequency response distortion.
2. Light weight, which can release the maximum acceleration in transient state and reproduce complete sound details.
3.W-shaped core foam is covered with two layers of special glass fiber structure.
4. Internal damping-eliminate ringing or resonance of any cone structure and reduce the occurrence of sound dyeing problems.
Diaphragm made of different materials has different characteristics. Paper is a light material. Although it is not hard enough and has good internal damping characteristics, the sound is often affected by paper to produce sound staining. Polypropylene polypropylene/plastic is a relatively heavy material, but its internal damping characteristics are quite good, its rigidity is acceptable, and its sound quality often lacks details and accuracy. Kevlar's simple woven Kong Long sound basin (without interlayer sound basin) adopts resin sealed sound basin, which makes it rigid enough to meet the demand, but it makes the plastic sound dyeing dull and disgraceful.
1980, Focal-JMLab successfully developed a new acoustic basin with light weight, high rigidity and high internal damping, and obtained relevant patents. This is the [Polykevlar] sandwich acoustic basin. The woven Kevlar tissue surface and hollow glass particles mixed with resin are used as sandwich cores. This structure shows the characteristics of high stiffness and low mass, and the damping coefficient can be controlled by the core components.
The birth of the "W" sandwich basin shocked the audio industry, and the industrial technology also obtained an exclusive patent.
The analysis of laser interferometer shows that the "W" structure cone has the best stiffness/damping/mass characteristics.
The birth of the "W" sandwich sound basin shocked the sound industry, and the industrial technology also obtained an exclusive patent. Starting from the original structure, the technology has been continuously improved and developed, and a new generation of Polykevlar sandwich sound basin has been developed. The biggest evolution of cone structure is the use of foam with special structure in resin and glass particles. This kind of foam is mainly used in aerospace field, and no foam has the same high stiffness/mass ratio.
The name "W" comes from Vere-Vere (Vere means glass), because the "W" type sound cone adopts two layers of fine glass fiber structure lighter and thinner than Kevlar Kong Long symbol, and the molecular attraction between foam and glass fiber is stronger than Kong Long symbol, so the sound cone structure has stable mechanics and excellent rigidity, and this structure also makes the sound wave propagation speed in the sound cone more ideal.
The difference between the structure of glass fiber and the thickness of foam allows us to make the most suitable cone structure for different purposes or performance frequency domain. W-shaped cone can produce excellent transparency and neutral signal reproduction, and there will be no sound dyeing and distortion accompanied by ordinary monomers. Its only natural limitation is its high production cost, which is ten times higher than that of high-quality paper tube monomer.
The traditional tweeter with convex cone diaphragm has the form of poor mechanical coupling of voice coil on the outer circle of diaphragm, and a considerable degree of mechanical force can be lost on the hanging edge, which is finally wasted as heat energy.
Focal-JMLab's concave diaphragm treble: The mechanical interface between the voice coil and the diaphragm is quite ideal, and the force can enter the diaphragm tangentially, and all the energy is transferred to the diaphragm and radiated by sound waves.
Cross-section analysis of TRC triple monomer. Note that the back room is used to absorb the return wave: the distortion is reduced and there is no compression dynamically. Labels 1, 2 and 3 correspond to lower response curves.
This is a high-pitched unit specially designed for the new Electra series. Its main feature is a concave basin diaphragm with Tioxid 5, a powerful double magnet system and a damping sound chamber, which is used to absorb the echo of the diaphragm.
According to the principle of small size monomer, the concave diaphragm combined with the central fixed voice coil structure can not only improve the power load capacity, but also extend the frequency response to the intermediate frequency range. Because of this excellent extended response capability, the frequency division point can be adjusted downward and enough space is left, thus eliminating the [beam concentration effect] from the middle and high monomers. The so-called beam concentration effect is that the directivity of high-frequency sound waves emitted by the cone will be enhanced, and even a beam will be formed. For the monomer of 165mm, the beam concentration effect will begin to appear at 2.8kHz, so the ideal frequency division point must be limited below this frequency.
In theory, the traditional convex basin monomer radiates energy at 180 degrees in the form of a semicircle, but it is not always the case. No matter the size of the reproduced signal, the diaphragm always keeps the same shape and moves along the circle without vibration effect. As can be seen from the figure, the convex basin voice coil surrounds the edge of the connection between the diaphragm and the suspension edge, and the energy transferred from the voice coil to the diaphragm is concentrated at the edge, so the energy is limited, which cannot be effectively dispersed into the whole structure, and the diffusivity of the diaphragm is not ideal. In this way, the traditional treble monomer of convex basin diaphragm is bound to be difficult to overcome this shortcoming. Because of its poor coupling mode with air, it can not produce downward extending frequency, and the voice coil structure attached to the diaphragm also has the phenomenon of dynamic compression. It can be clearly seen that the concept of circular vibration and its principle of balanced diffusion are not ideal. If the tweeter unit with concave diaphragm is used, the position of the voice coil is equal to half the height of the diaphragm, so that the whole diaphragm can bear more consistent force, and then the whole structure radiates outwards with the best efficiency, which is an ideal air coupling mode. In addition, the connection with the alto monomer can be extended down to 2.5kHz, thus improving the propagation directivity of the alto monomer!
The evolution of TiO _ Xid material originated from TGU tenor monomer used in Utopia. TiO _ Xid _ 5 has the same mass and stiffness as titanium, but it has better damping characteristics. In the diaphragm with only 5 microns precision compression, TiO _ Xid _ 5 is lighter than the original shape, and with higher internal damping coefficient of TiO _ Xid _ 5, the sound is smoother and more accurate, and there is no metal contamination. The best double magnet system and echo damping sound chamber.
In order to obtain maximum efficiency, the single structure of the tweeter unit includes a double magnet system, which makes the magnetic beam more concentrated and reduces leakage. The gap can produce a magnetic field intensity as high as 1.5 Tesla, and then the back wave energy is led to the rear sound cavity filled with sound-absorbing substances through a special structure, so that the back wave of the diaphragm can be effectively suppressed. In this way, this is an ideal high-pitched monomer with extended low-frequency response, extremely low distortion and deep sound stage.
Focal-JMLab's unique concept of concave diaphragm is formed by accumulating 20 years of manufacturing experience, from which we find out how to control the response curve. This kind of research can avoid using frequency division circuit to correct the response, and never mistakenly think that the defects in mechanical design can be corrected by electronic circuits. The frequency response of TRC tweeter is precisely controlled by the following three aspects:
1, the downward connection between the overhang/bracket and the rear sound room.
2. The connection between voice coil and diaphragm is related to the response of the middle part.
3. The phase cone relationship is very sensitive.
Optimal phase crossing
If the acoustic transducer has the best response, then the crossover line only needs to consider the basic frequency distribution, which is the basic penetration of the OPC optimal phase crossover line. The quasi-control electrical signals of Qualcomm and low-pass frequency division line completely conform to the frequency response range of the connecting monomer.
Frequency division circuit can be said to be one of the key points in loudspeaker design. Its function and design are really quite complicated, and it can shape the speaker's unique personality.
The frequency division circuit is responsible for distributing the signal sent by the amplifier to a single unit: bass, midrange and treble. Undoubtedly, the most important filtering area lies in the high frequency response, and the Qualcomm filter circuit attenuates the low frequency response of the tweeter. The dividing point is usually arranged between 2 and 5 kHz, which leads to the baseline of the directivity of real sound reproduction.
The diameter of the monomer used to reproduce the intermediate frequency range is usually between 13 cm and 17 cm, which can respond to the frequencies of 2kHz and 2.6kHz tones. Directivity refers to the angle at which a single body radiates sound waves, which decreases with the increase of frequency. When the frequency wavelength is shorter than the diameter of the diaphragm, the sound directivity becomes obvious, and the sound wave radiation will form a narrower beam. Therefore, according to the principle and standard of two-dimensional playback of real audio and video, the acoustic energy radiated by a single body is unbalanced. Because the design and concept of concave treble monomer have excellent characteristics, its frequency response can be extended downward enough to avoid the influence of beam concentration of alto monomer.
In addition to the limitation of the insufficient response of the general treble monomer extending downward, there is another important point, that is, the phase response of the speaker and the frequency division circuit combined with the important range. Ear and hearing are very sensitive to the frequency between 2.5kHz, and the amplitude response of the midrange unit and its frequency division circuit must accurately correspond to that of the treble unit and its frequency division circuit. If this standard can be reached, the phase between the alto and the alto monomer can be consistent, so that the overlapping frequency domains can complement each other perfectly, and then a balanced timbre performance can be produced. The phase difference between the crossover points of the treble and the alto monomer must be zero, so that two different radiation sources at the crossover point can produce symmetrical and deep depressions.
According to the above viewpoint, the technical basis of OPC optimal phase frequency division circuit is established.
However, it is naive to think that it can be realized only through the technical research and development of frequency division circuits, because the reaction and performance of monomers must be accurately grasped first. This is only possible for a few manufacturers, such as JMLab, who develop their own monomers, and each monomer is specially designed for different products.
1, when the frequency increases, the radiation directivity of the bass monomer will be enhanced, so before this phenomenon begins to appear, the treble monomer must be added to the crossover line.
2. At the frequency division point, the phase relationship between the treble and the bass monomer will produce a directional blade-like acoustic radiation pattern. On the left is the common trivalent Butterworth crossover line, and the blade-like radiation area is not consistent. The OPC frequency division line on the right shows that the blade radiation area is exactly the same.
3. Frequency response of positive and negative phases. Electra 906 shows a completely symmetrical phase decay state, which means that the actual phase response is perfect and consistent.
By using OPC optimal phase dividing line technology, a 36dB/ octave frequency dividing attenuation slope is used between the treble and the alto monomer to maintain perfect phase response. The converted sound sequence is not only completely consistent, but also has pure and neutral timbre, accurate audio-visual and extensive radiation, so that a wider range of listening devices can enjoy high-level sound quality at the same time.