1. The special features of the speaker's electrical function
speaker's electrical function is mainly used in two aspects: power transmission (commonly known as speaker line transmission. That is, power amplifier signal transmission) and voice coil work. The function of power transmission is different from that of voice coils doing work: power transmission does not require electromagnetic conversion, and voice coils doing work requires electromagnetic conversion. Therefore, it has its own electrical function speciality.
1.1. The relationship between sound wave and electromagnetic wave
speaker sound wave is converted by electromagnetic wave and then driven by the diaphragm. The electrically conductive current-carrying frequency determines the speaker sound frequency; the electrically conductive current-carrying quantity and voltage determine the speaker amplitude. That is, power determines the amplitude.
The electrical conduction current-carrying frequency of load music information is referred to as audio for short. The audio current must be alternating current or alternating current. Only AC can load and transmit musical information based on frequency variation. The sound waves of music are mechanical waves based on frequency changes.
mechanical wave and radio wave (or electromagnetic wave) are two different substances: mechanical waves are generated by mechanical vibration; electromagnetic waves can be generated by periodic movement of electrons, the inner or outer layer of electrons of atoms are excited, and the atom nucleus is stimulated, etc.
The sound waves in mechanical waves are two-dimensional, with only energy and shapes, and no protons; electromagnetic waves are three-dimensional, with both energy and shapes, and protons. Electromagnetic waves have " wave-particle duality ", and sound waves only have waves but no particles. Therefore, sound waves must rely on medium (protons) to propagate, while electromagnetic waves can propagate with or without medium (protons).
is the case. The propagation speed of sound waves is determined by the medium: on the one hand, the propagation speed of sound waves of different frequencies of the same medium is the same, and on the other hand, the propagation speed of different frequencies of different mediums is different; but the propagation speed of electromagnetic waves in the same medium (due to the refractive index relationship n=c/v) is different. If the frequency is greater, the higher the refractive index is higher and the propagation speed is smaller.
Generally speaking, the propagation speed of sound waves using air as medium is 340m/s at temperature condition 15C0, but the propagation speed of electromagnetic waves in any medium (including vacuum) is close to 300,000 kilometers per second, ≈ speed of light (1 speed of light (c) = 299792.458 kilometers per second (km/s)).
Sound wave propagation speed (sound speed) of different media is shown in Table 5 below:
material | M/s (meter/second) | |
aluminum | 6305 | |
gold | 3251 | gold | 3251 | 1 0 | magnesium | 5791 |
silver | 3607 | |
copper | 4394 | |
titanium | 6096 | |
nylon | 2591 | |
ceramic | 5842 | |
Plexiglass | epoxy resin | hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh5h2540 |
3 cemented carbide | 6985 | |
Polytetrafluoroethylene | 1422 | |
PVC | 2388 |
table 5Dimedia velocity meter
The radio wave speed is not affected by the medium, but the sound speed is affected by the medium. Judging from the speed, the speed of sound and the speed of electric are not the same order.
However, different frequencies of sound waves are the same in the same medium, while different frequencies of radio waves are the same in the same medium: because the higher the frequency, the higher the refractive index, the lower the speed.
This brings up a problem: since the speed of sound is different from the electric speed, how is the frequency in conductance unified with the frequency of sound?
can only be understood as: the length of the radio wave > the length of the sound wave (when air is used as the medium) is more than 882 times. The 50Hz transmitted by the electrical conductor is converted into the sound wave transmitted by the air. The two have different shapes and quality, but the quantity is the same. That is, heterogeneous isomorphism.
In addition: the intensity of the sound wave is determined by the amplitude; the intensity of the electromagnetic wave is determined by the voltage and current (power).
This is the physical mechanism of electromagnetic (magnetic) sound conversion. It is also the relationship between electrical frequency and acoustic frequency. In this electrical and acoustic relationship, the conductance of the speaker contains its own particularity.
1.2. Multi-frequency transmission and multi-state transmission
The special feature is first manifested in multi-frequency and change.
multi-frequency: The frequency of the audio electrical load or transmission is at least 20Hz~20KHz. Compared with other non-audio electrical load or transmission single 50Hz or 60Hz or even higher frequencies, the frequency is 20,000 times more (1 single frequency compares 20,000 frequencies);
multi-frequency: The electrical function of the audio electrical load or transmission is timely and varied. The changes in the mechanical waves of music change with the strength of music energy, the frequency of music, the light and darkness of music tones, etc., including both time and spatial changes, resulting in complex and rich changes in the audio and electrical functions. The current and voltage are always in time to change. This is a feature that other non-audio electric loads do not have.
1.3. The use of electric power of speakers
electricity and magnetism are two sides of a substance: there must be magnetism when there is electricity, and there must be electricity when there is magnetism, and electromagnetic is inseparable. But in the application of speaker electrical power, it is applied separately.
1.3.1. In power and frequency division application
audio, the wires used for weak current transmission are called signal transmission, such as the wires at the front end of the power amplifier are used for weak current transmission; the wires used for strong current transmission are called power transmission, such as the wires at the back end of the power amplifier are used for strong current transmission.
power transmission for frequency division is an important experience in the development of electroacoustic technology: it is wise to divide the frequency into high or low frequency. Because the diaphragm used for high-frequency must be light and thin, the response time of high-frequency vibration can be met. The higher the frequency and the shorter the vibration period, the more the response agility of the diaphragm is required, and the low-frequency response is the opposite. The full frequency unit does not divide the frequency and does not meet the high fidelity conditions. The frequency division of the speaker unit is the frequency division of the power division. The passive divider (also known as the power divider) of the
speaker is placed at the front end of the speaker and the back end of the power amplifier. It is often used to use the inductor for low pass, and the capacitor for Qualcomm for .
inductor stores energy in the form of inductive reactance, hindering the passage of high-frequency current, reactive power is consumed in large quantities on high-frequency current, active power is exerted in low-frequency current; capacitors store energy in the form of capacitive reactance, hindering the passage of low-frequency current, hindering the passage of low-frequency current, hindering the passage of reactive power is exerted in low-frequency current, and active power is exerted in high-frequency current.
capacitor consumes reactive power (KVAr): Qc=2×π×f×U2×C (U=voltage, unit: KV, C=capacitance, unit: μF).
Inductance consumes reactive power: Ql=U2/(2×π×f×L) (f=frequency; L=inductance)
This application is focused on the "current" aspect of electromagnetic waves.
1.3.2. The medium for the magnetic field to use the
speaker to produce sound is the diaphragm. The movement of the diaphragm is driven by the voice coil, and the movement of the voice coil is driven by the magnetic force. On the one hand, the movement of the magnetic force depends on the magnetic field force of the magnetic air gap, and on the other hand, the electric (generated) magnetic force generated by the voice coil winding. The power dissipated by electro-generated magnetic is considered reactive power by ordinary electrical functions, but it is exactly the opposite in speaker voice coil applications: the power consumed by electro-generated magnetic diaphragm is precisely the active power of the speaker voice coil driving diaphragm. This is in line with the physical significance of all electromagnetic waves focusing on magnetic work.
Relatively speaking, the "magnetic" of the electromagnetic part in the voice coil wire is active power. However, any conductive material has a resistance at room temperature, and part of the power is converted into thermal energy and consumed due to the resistance. Therefore, in terms of the power of the voice coil, only the magnetic part is active power. Among them, the power consumed by resistors, ionization energy, , etc. is reactive power. The power consumed by the resistance of the
electrical conductor is not only the reactive power of ordinary applications, but also the reactive power of the speaker including the voice coil circuit; the difference is that the reactive power consumed by the electromagnetic part of the magnetic part in ordinary applications is exactly the active power of the speaker's voice coil.
It should be noted that the active and reactive functions of the voice coil cannot be the same as the other conductivity rules of the speaker. Except for the voice coil conductance, everything else is the same as that of ordinary electrical function applications.
Among them, the most obvious part of reactive power is the resistance of the electrical conductor. From the perspective of apparent power, the greater the resistance of the electric conductor, the smaller the active power of the speaker, the smaller the resistance of the electric conductor, the greater the active power of the speaker. This rule is also suitable for the voice coil conductivity function. The smaller the resistance, the larger the current, the more magnetic current, the stronger the magnetic force.
However, the principle that ordinary reactive power in the voice coil conductance is inversely proportional to the frequency and proportional to the frequency is also reversed: the greater the active power, the smaller the frequency, and the smaller the active power, the greater the frequency. This is also the reason why the smaller the BL value, the lower the frequency, and the larger the BL value, the higher the frequency.
In other words, from the perspective of apparent power, the power is strong, and the power is weak.
In this way, the active and reactive power of the speaker's electrical function is no different from the active and reactive power of ordinary circuits: they are all related to the material and shape of the electrical conductor. The most direct thing is related to the resistance value of the material.
2. Power transmission line design
speaker power transmission line design can consider three aspects: speaker-Amplifier line, voice coil line, and inductor line. Among them, the speaker cable refers to the amplifier output end to the speaker driving unit input end.
The three differences are: the speaker wire is not in a single unit or device, and there is no space limitation, so it can be relatively free in material and shape; the voice coil wire is structured in the single unit of the driving unit, that is, in the magnetic gap, with large space limitations, the material and shape are difficult to free, and the selection surface is very narrow; the voice coil wire and the speaker wire have something in common, and the material and shape are highly selective, the difference is that it is curled, and improper design is likely to generate parasitic capacitance, which affects the stability of the inductance indicators. The application environments are different between the three.
2.1. Vibration environment
speaker cable is a power transmission line connected to one end of the amplifier output and the other end of the speaker (or speaker) input. According to the application environment, it belongs to the "outside the machine line" (opposite to the inside line). It is precisely because the environment he is in has its own special nature. The use of conductive transmission lines in
audio system cannot avoid the dynamic environmental impact of the current loop, that is, the impact of dynamic electric field.
In the static electric field, that is, the entire audio system has not yet established an electric field for power-on, the conductive transmission lines, power amplifiers, frequency dividers, speakers, etc. are in their respective isolated electrical states. Once the system is powered on, the audio systems such as conductive transmission lines, amplifiers, frequency dividers, and driver units jointly establish a dynamic electric field. This electric field no longer retains its isolated electrical properties, but forms a mutually coordinated and contradictory dynamic electric field jointly established by conductive transmission lines, frequency dividers, speakers, amplifiers and other equipment. The different electrical properties of each link in this electric field are coordinated and contradictory, forming a special dynamic of the current loop environment. For example, the speaker line as a conductive transmission line will be affected by changes in the resistance, inductance, capacitance and other factors in the frequency divider. Changes in the inductance value and capacitance value of the frequency divider will affect the change of the electrical load of the horn line conductor; on the other hand, in the loop, electrical energy uses magnetic energy to drive the diaphragm to make the diaphragm to make sound, and the vibration of the voice coil and its diaphragm will generate a large back electromotive force . The diaphragm converts electrical energy into sound energy during vibration, and the sound energy of the diaphragm vibrating is also converted into electrical energy. The converted part of the electric energy will form a back electromotive force superimposed on the electric field of the horn line, that is, the conductive transmission line, causing greater electrical performance interference to the horn line, that is, the conductive transmission line.
On the other hand, although electromagnetics are two sides of one body, according to the Chinese thinking, the two are yin and yang, which are mutually generated and restrained. Coincidence: Electromagnetic generation is defined by Western science as electromagnetic effect ; magnetic electricity generation , defined by Western science as magnetoelectric induction; strong electricity is strong, weak magnet is weak. Corrosion: Magnetic field interferes with electric field, electric field interferes with magnetic field, especially in the same conductor or conduction medium.
Usually, the electromagnetic effect is: the influence of the dynamics of the sound wave vibration environment on the conductive transmission line.
: If a speaker makes sound, the environmental space in which the audio system is located and its entire sound field are vibrating. Vibration affects all links. Experience tells us: if you replace the amplifier, CD, and speaker with different materials, you will hear different sound quality and tone performance.As a load-bearing object of the equipment, the foot nails are not energized and are not in the electric field of the entire system. Then why can foot nails change the sound effect of the system? This is because the resonance frequency of foot nails of different shapes and materials is different. The vibration frequency of transmitted to the audio device is different from the vibration energy, resulting in changes in the system sound quality and tone. Therefore, the vibration of acoustic waves in the same space will have a vibration effect on all the circuits of the system.
speaker cable is no exception. In a sound wave vibration environment, the speaker line will produce a piezoelectric effect due to external forces: that is, an electrical load with opposite polarity is generated at both ends of the conductor (contact points) or under certain frequency and voltage conditions. The amount of electrical load derives an alternating and superposition of the electric field of the conductive transmission line, or it may be that the resonance decreases to form a deformation interference to the electric field of the conductive transmission line - acoustic dyeing.
is based on the above two major influences. As a conductive transmission line in the audio system under the requirements of high-fidelity transmission performance, its conductive resistance and shock resistance are particularly important. The so-called mutual inductance resistance is to resist the dynamic influence of the current loop environment; the so-called earthquake resistance is to resist the dynamic influence of the acoustic vibration environment.
is considered based on the above two major interference factors, and the speaker wire should be selected from four aspects: material, shape, insulation and earthquake resistance.
2.2. Horn cable design The environment in which the
Horn cable is located is the application prerequisite for the horn cable design. Just as the application environment considered in the design of off-road vehicle is potholes and uneven mountains.
As for general household high-fidelity speaker cables, the first thing to choose is silver conductors. (See the table below)
atomic number | gold | silver | silver | copper | aluminum | |||||||||||||||||
electronic layer arrangement | gold | gold | silver | silver | silver | silver | html aluminum | |||||||||||||||
atomic radius | silver | copper | aluminum | aluminum | gold | |||||||||||||||||
electronic configuration | gold | silver | 1 silver | 112silver | 1112silver | 1112silver | 1112silver | 11112silver | 11112silver | 11112silver | 11112silver | 11112silver | 11112silver | 11112silver | 11112silver | 111112silver | 111112silver | 111112silver | 111112silver | 111112silver | copper | aluminum |
aluminum conductivity | silver | silver | silver | silver | silver | silver | ||||||||||||||||
thermal conductivity | silver | silver | ||||||||||||||||||||
silver | copper | gold | aluminum | |||||||||||||||||||
ionization energy | silver | copper | aluminum | aluminum | gold |
table 6. The priority ranking table of the physical and chemical mechanism of common speaker lines
. The industry and enthusiasts generally believe that silver conductors are suitable for transmitting high frequencies. This view has no more theoretical support. In fact, silver conductors not only have small losses in high frequency, but also have minimal losses in low frequency.
According to my analysis of the physical and chemical mechanism of electrical function transmission in the previous analysis, silver conductors rank first in the industry with very sensitive conductivity; secondly, the ionization energy is the smallest (comprehensive calculation from first ionization energy to the seventh ionization energy); the largest atomic radius, etc. This shows that silver conductors are stable and easy to "handle" electronics, and have the smallest reactive power. Especially for multi-frequency currents for music information. The music information loss of the current load is minimal.
Regarding the problem of speaker cable material and music telecommunications, people on earth rarely conduct scientific research. Even some publicity that goes against common sense in physical science will harm the public.
, such as the American "Music Ribbon" speaker cable, which is famous for commercial hype, introduces its products: "The following amazing numbers are the technical indicators of the top music ribbon speaker cable Valhalla (Vahara). Please take a look first: insulation material : high-purity first-class extruded Teflon; conductor: 40 micro-space insulation structure optimal diameter; material: 78μm extruded sterling silver surface on 8NOFC pure copper surface; capacitance: 11.8pF/ft; inductance: 9.6μH/ft: DC resistance: 2.6Ω/1000ft (304m); transmission speed: 96% light speed." Its series of wires also have nominal 91% light speed.
Regarding the conductive material of music ribbon, some are introduced as copper-plated silver, some are introduced as "extruded silver". The thickness of silver is claimed to be 78μm or 70μm, and the inner core is claimed to be 8N oxygen-free copper. Its biggest commercial selling point is the last few words: "96% speed of light". Among them, there are also nominally 91% speed of light.
This gives people two major questions: First, has the music ribbon technical team learned physics in middle school and created cables that completely violated the common sense of physics? Electric speed = light speed, which is confirmed by Einstein in general theory of relativity . The electric speed of the cable it built is "96% light speed". What's this thing? If you don’t understand the common sense of physics in middle school and talk nonsense, then such a technical team is completely untrustworthy, and the technical nomenclature they make is a lie; second, the technical team of the music ribbon technical team is "awe" to the super physics level that can control the speed of electricity at will, completely subverting the world’s physical science and reaching the non-physical science situation that people on earth cannot understand.
judged by the range I know, the former is more likely: speak nonsense and talk nonsense. Treat the market as a fool who is stupider than yourself to commit a bottomless deception.
In order to confirm its lies, I specially bought music ribbons to listen and compare. The result is a mess. The ultra-low frequency does not have, the mid frequency is not full, and the high frequency is not transparent. It is not much different from the 2.5 yuan/meter speaker cable on the market (the music ribbon is priced at 2,800 yuan/4 pieces), and it is completely inaccessible to the Hi-Fi level. Especially low frequency performance.
I briefly compare the speaker cable developed by our institute with the following table:
speaker cable and brand | shape and process | length (cm) | frequency resistance value 100Hz/mR | frequency resistance value 1000Hz/mR | frequency resistance value 10000Hz/mR | ||
China Central Audio Academy | Rectangular cross-section 5N-N material | 150 | 13 | 13 | 13 | 13 | 13 |
Taiwan Jiquan | Circular cross-section 7n Single crystal copper | 100 | 23 | 23 | 23 | ||
American music ribbon | round cross-section silver bag 8N oxygen-free copper | 1 00 | 20 | 20 | 22 | ||
Comparison results | ↑50% | ↓44%~34% | ↓44%~34% | ↓44%~34% | ↓44%~41% |
Table 7 Comparison of electrical properties of 5N-N materials and 7N single crystal copper and silver-clad copper materials
In Table 10, 5N-N guide material is a new type of music power transmission line number invented by the China Academy of Sciences Acoustics (Guangdong) Science. Among them, "5N" refers to the purity of the metal material, and "-N" is the name code of the material (superconductor) that is commercially confidential. In the comparison of
, the length of 5N-N exceeds 50% of the length of the comparison group, but the resistance values of each frequency band are <34%~44.>
Goodbye to the following test data:
5N-N Test instructions: 5N-N test is conducted under the condition of connecting 19 22cm long gold and silver leads + oxygen-free copper rhodium-plated plugs on the crimping process. Its resistance values are different from those in Table 100Hz, 1KHz and 10KHz, and are all caused by the addition of leads and their plugs. | Hz | resistance (mΩ) | inductance (μH) |
20 | 63 | 0.65 | |
50 | 63 | ||
50 | 63 | 2 | 100 | 63 | 2.8 |
250 | 63 | 2.8 | |
500 | 63 | ||
63 | 2.82 | ||
| https://www. ml21000 | 63 | 2.8 | |
2000 | 63 | 2.75 | |
5000 | 64 | 2.72 | |
100 00 | 64 | 2.72 | |
15000 | 68 | 2.67 | |
20000 | 70 | 2.66 |
table 11 Statistics on the change of resistance values of each frequency segment of 5N-N
Table 11 shows that the increase in the resistance value of 5N-N starts from 5KHz (increasing 1.6%), and increases by 7mΩ (increasing 11%) to 20KHz. Comparing the test parameters of Table 10, the increased resistance value is entirely caused by the leads and plugs. Because in Table 10, the 5N-N resistance values 100Hz, 1KHz, and 10KHz have no changes. The resistance of the music ribbon at 10KHz increased by 10%. This shows that the design of its 68μm silver-encapsulated material part has not achieved the effect of reducing the skin effect of : that is, the depth design of the skin effect is unreasonable. This may be the reason why the music ribbon feels dull and dull, and cannot go up or down. The characteristic of
-N material on another level is its anti-magneticity. Under certain conditions, because of its anti-magnetic nature, magnetic waves are difficult to penetrate it, so the eddy current of magnetic interference is lower. Except for the resistivity higher than silver under certain conditions, its electrical properties exceeds silver. This defect can be improved by shape design. This can be seen from the above list.
According to the above-mentioned neutralization selection principles of material, shape, insulation and earthquake resistance, the core conductor material of 5N-N is selected as a superconducting material, and the shape is selected as a foil belt type, that is, a rectangular cross-sectional shape. It uses stealth aircraft technology to perform wave absorption processing to improve the eddy current interference brought by the electromagnetic effect, and is specially wrapped with a thicker shock-proof layer. The design of
makes the 5N-N feel far more effective than all speaker cables on the market that make money by telling stories. Even more than the horn cable of Dutch Crystal Color 350,000 Hong Kong dollars per meter.
3. Voice coil wire design The application environment of the voice coil wire is different from the speaker transmission line, and the application goals and methods are also different:
For dynamic coil speaker , first, it is in a narrow magnetic air gap environment, and its shape is greatly restricted; second, its application goal is electromagnetic, not purely conductive; third, the application method must be in a circle, not straight. This requires inductance to be generated. It's actually an inductor.
3.1. Voice coil wire material
The driving of the voice coil does not rely on electricity, but on magnetism. In other words, the electrogenerated magnet of the voice coil forms a 90-degree tangent magnetic line with permanent magnets (or excitation ), and moves by changing characteristics of the alternating direction of the alternating current. The higher the conductivity, the stronger the magnetic force, the smaller the force loss.
According to the above-mentioned guide material comparison, it is of course best to choose silver as the voice coil wire.
We did a comparative experiment: voice coils of two different conductive materials: voice coils of sterling silver wire voice coils and copper-clad aluminum wire voice coils.
All conditions are the same, the only difference is that the material of the wire is different. The comparison results are as follows:
Figure 5 Comparison of frequency response curves between silver coils and copper-clad aluminum coils
Figure 5 shows: The average sound pressure level of silver wires > 5dB of copper-clad aluminum wires, and the frequency response unevenness is <5db.>
analysis: This is a dynamic tweeter application. The reason why copper-clad aluminum is used is to reduce the weight of the voice coil. The density of aluminum is 2.7 and the density of copper is 8.8. Aluminum is three times smaller than copper.The resistivity of aluminum is far > copper, so it is wrapped around the outer layer with copper, which reduces the skin effect and produces current-carrying hollowing, which is more conducive to the higher frequency current-carrying passage. The smaller the density, the lighter the mass, which is more conducive to higher frequency vibration response. Anyway, the frequency division of the tweeter is above 2KHz or even 3KHz, so the aluminum core part is in the center of the circular cross-sectional area, and its resistivity has no substantial impact. Because the current at the 2KHz frequency has already tended to the cross-sectional area surface. Changing the frequency with weight is effective for the tweeter.
Figure 5 shows the absolute advantage of silver coils. What is the reason?
silver has the smallest resistivity, conductivity, has the highest electric magnetic function, so it accepts the magnetic line of the magnetic gap and is more sensitive to the effect of . All other conditions are the same. Only when the material is different, it actually reaches a difference of 5dB. It can be imagined that its active power can be 1.8 times as effective as copper-clad aluminum. In other words, the efficiency of one silver coil unit is equivalent to that of three copper-clad aluminum coil units. In other words, the silver coil is more effective in changing weight to the efficiency of the tweeter than to changing weight to vibration.
There are very few sterling silver coils on the market. And I often hear that silver coils have too many high frequency. This is also without theoretical basis. What is overshot? It is best to answer with objectively evaluated instrument tests. As long as the curve is flat, it won't be overdoing it. The reason for overthrow is likely to be the "explosion" sound caused by insufficient diaphragm strength. It's not about the coil guide.
In short, silver-wire voice coil is the first choice for advanced speaker system material performance.
3.2. Voice coil wire shape
There are only two options in terms of voice coil wire cross-sectional shape: one is a circular line, and the other is flat line .
In the wire shape, "under the same cross-sectional area (17mm2), flat wire is rounder: the actual current-carrying area at 20KHz is >2 times, the DC resistance is <50%,>6.7 times. The shape of flat wire has absolute advantages over roundness" (see "Shape and Electric Power" - "Cross-Shape" before the article), it is naturally better to choose flat wire.
However, the article also mentioned that "the skin effect of the ribbon line is reduced compared to the flat line."
Why not use a strip-shaped cross-section rectangular shape?
Because the cross-section rectangular line has 4 sharp right angles. During the production of enameled wire, the insulating paint is encapsulated in such a way that the thickness of the insulating paint wrapped around the wire is basically the same. Therefore, those 4 acute angles insulating paint can easily get injured or insulating missing corners in the winding. The flat wire winding of the voice coil of
is a vertical winding. The sharp angles of square lines between turns, between layers and layers may be damaged or scratched, which is very unsafe and has a high defect rate. Therefore, there are few or no square lines to be used. Another advantage of using flat wire as voice coils in
is that its magnetic stroke is larger (see Figure 6 below).
Figure 6 Schematic diagram of the magnetic stroke comparison between circular lines and flat lines
Figure 6 Schematic: The distance between the north and south poles of the flat lines is larger than that of the round lines. Under the influence of the magnetic force in the permanent magnet or the excitation gap, the alternating stroke of the north and south poles of its own magnetic force is larger, so its stress is greater. The magnetic field utilization rate of circular lines is 78%~91%, and the flat lines are about 96%. Don’t underestimate the 5% difference. The appropriate magnetic circuit design may be an improvement in efficiency of 1~2dB.
In my discussion on the diaphragm efficiency issue, I mentioned: efficiency includes benefits. The more efficient the more details of music information are preserved.
3.3. Voice coil wire and magnetic circuit are combined with
. In the experiment comparison between circular and flat lines, it cannot be switched and compared on the same magnetic circuit. Instead, it should be compared under the same voice coil single-sided magnetic gap condition.
The inner diameter and outer diameter of the circular voice coil and the flat voice coil are different. The inner and outer diameter of the flat voice coil > the inner and outer diameter of the circular voice coil. When compared in the same magnetic gap, the flat line voice coil is single-sided magnetic gap voice coil single-sided magnetic gap is a touchstone for testing the level of speaker production. If the magnetic gap is designed to have a single-sided distance of less than 10μm, it may not be created. Currently, it is already the top manufacturing that can achieve a 20μm single-sided magnetic gap. If a single-sided magnetic gap of > or <5μm> voice coil wire, shape, bobbin and other process design are closely related to the coordination between magnetic gap, diaphragm, elastic waves and folding rings. If the diaphragm deforms, it will affect the voice coil deformation, and the voice coil deformation will affect the magnetic field deformation. Therefore, the single-side distance of the voice coil of the magnetic gap must also retain a certain amount of room for heat dissipation and deformation. coil moves at high speed in the magnetic gap and heats up very quickly (under 30C0 indoor conditions, the temperature rises up to 70C0). The temperature rises up the resistance. The heating of the flat line is only 7% of the circular line. It can be imagined that the resistance and temperature rise of the flat line are better than that of the circular line. inductor wire is also one of the speaker power transmission lines. The difference is that its application is between the speaker driver unit and the terminal block connected to the speaker cable. Its main function is to play the role of low-pass filtering for power frequency division and passive frequency division. In low-pass applications, the impedance of the inductor changes with the frequency, and the impedance is proportional to the frequency: the higher the frequency, the greater the resistance. It is filtered with this performance, that is, low frequency passes and high frequency blocks. speaker passive frequency divider inductor design, it is best to choose materials with larger atomic radius such as silver. Because current carrying is its first function, intercepting is its second function. Its intercept is mainly aimed at higher frequency currents. For the stability of its current-carrying part current, of course, it is best to use materials with high active and low energy properties represented by silver. Of course, if you use sterling silver materials, the cost will be very high. The price of 3N sterling silver in September 2022 was 4.1 yuan/gram, and the price of copper during the same period was 0.067 yuan/price. The price difference between the two is 61 times, making it more expensive after processing and forming. is used in the wire shape, of course, the cross-sectional rectangle is better. Because this is the most basic condition to ensure its first function (see the aforementioned "Shape and Electrical Function"). Such a shape is commonly known as a foil-band inductor. is based on this most basic condition. Under the requirement of ensuring a large load power, the ratio of the narrow side and wide side of the cross-section rectangle of the foil belt inductor is proportional to the load power. width-narrow edge ratio cannot be <3:1,>50:1. Because the inductor has a long winding (such as 0.23mH requires 8 meters), if you choose the foil belt shape inductor process and the material is silver foil, the cost is indeed outrageous. , such as 0.1mm×25mm×8m silver foil, the conductor cost is about 10,920 yuan. If users cannot accept such a high cost, they can choose single crystal copper foil with a temperature of more than 4N, which is much cheaper. In terms of conductivity, single crystal copper is only 5% lower than sterling silver. However, the details and stability of the music conductance are worse. In addition, except for material and shape, the manufacturing process is also very important. , such as Mondofos, Germany and Danish God of War, the conductor is made of oxygen-free copper, the shape is foil belt, but the insulation material is polypropylene film. Because the insulation interval is too thick, parasitic capacitance is easily generated, which affects the stability of inductor frequency division; and in contact with polypropylene and copper are prone to corrosion reactions and have a short life. parasitic capacitors, also called distributed capacitors, are a technical bottleneck in inductor manufacturing. We are working on solving it. 4. Inductor wire design
4.1. Wire selection
4.2. Shape selection
