The function of the filter capacitor in the power amplifier power supply is threefold: 1. Filter the pulsed direct current obtained after rectification to reduce the AC dry good. 2. High-speed power supply. 3. Provide a path for the audio signal. Capacitor's filtering effect on the power supply, for the power amplifier It only shows whether there is communication interference; the energy storage function of the capacitor can provide power for the transient high current of the power amplifier, but the power of the transformer cannot be charged in time, and its energy storage effect is not obvious; and it is an audio signal. It is also crucial to provide access to the sound quality and tone.
As shown in the example of the positive half-cycle audio signal, the signal is divided into two channels through the power amplifier tube, the emitter resistor, the speaker, and the ground. Some of them are formed by the Power Transformer and the rectifier to form a loop, and a part of the filter capacitor is used to form a loop. Obviously, the transformer inductance It is very large, which is not conducive to the passage of the high-frequency part of the audio. It can only pass the low-frequency audio signal with low frequency, and can only provide the path for the sub-woofer. More audio signals, especially the high-frequency part, form a loop through the power supply filter capacitor. Capacitors and transformer secondary complement each other, providing a frequency band from DC to high frequency for audio.
Production audio capacitors are estimated to be divided into 2 categories, 3 series, a large category; non-"dynamic" audio capacitors, this kind of audio capacitors and capacitances are more common, high frequency is clear, medium frequency is good, but low frequency is lacking. Second class "dynamic" audio Capacitance, the sound of the sound is domineering, the ready-made feeling is very good, the low-frequency retractable and free, is to listen to the high-frequency will be ten ears fatigue, the intermediate frequency is not enough tenderness. In the fine point is the high-frequency good audio capacitor for a series, low-frequency Good for a series, high and low frequency is a series, it is more difficult to find all three sides are very good performance, so there is a need to match the need to match this.
If you don't believe it, you can also search for the word [capacitance on the sound] [capacitor has no effect on the sound] A series of words are all tried in a variety of browsers, a lot of information but most of the sense of hearing, it is almost difficult to see the explanation The specificity of the capacitor can affect the specific cause of the sound. Including the foreign website is also the test of the ear of the burning friend. The foreign website has not yet found a detailed explanation of the capacitance, which causes the sound of the power amplifier circuit to change, and the large manufacturer ELNA can only check. There are no very specific explanations for optimizing the design and effects of audio capacitors.
The following article is the only one I have consulted in a large amount of information. I have a little bit of my own environmental conditions. The introduction should be a small and medium-sized capacitor manufacturer in Guangzhou. I have read the contents of the article carefully, although I dare not say the percentage. Hundreds is right, but most of them are worth learning and reference, but it is still necessary to remind everyone that the parameter indicators can only be used as a reference under normal DIY conditions. [Exactly, we can't get an overall indicator for comparison and reference.] The help of our DIY is only to know a knowledge, and it can't completely help us to design and adjust the sound according to the index parameters. It is not adjusted according to the data of the parameter index characteristics, but it is conditional and cannot be used. Parameter indicator data, why? It is clear who has a studio dedicated to sound design, there are a lot of test instruments to test the data, but also to organize the data for test calculation, but also repeatedly compare the test and then organize the data before finalizing. We are civilians DIY is not a big manufacturer. So do your best, do what you can do, discuss the scope of your ability, of course
Although the following information has been useful and long-sighted, there is still a distance from the actual application. It can only explain the reason. The actual use is supported by conditions. Naturally, conditions can be used. I have learned without conditions. Ear receiving goods!
Filter capacitor change sound cause analysis
I often see the effect of filter capacitors on the sound quality, but it is rare to see what causes a capacitor that filters the power supply to affect the sound quality. So many practitioners only know that it does have an effect but don’t know why. Blindness is self-evident. I am publishing my own opinion. The purpose is to study this phenomenon with everyone and find out the reason why the filter capacitor affects the sound quality. The filter capacitor is smoothing the stored energy of the pulsating current after rectification. The ripple factor meets the requirements and meets the requirements of the power supply at the rear stage. However, it also has an important task, that is, it also provides a common AC channel. Since the capacitance of the capacitor is different in the entire audio frequency range, it also brings The impact on the sound quality, this is the key reason. According to this reason, we can be very clear about the requirements of this capacitor. Conditional friends can test the entire frequency range of the internal resistance of the power supply, and then select the capacitance characteristics ( In particular, the post-stage filter capacitor is more important. It can also be compensated to make the impedance of the entire audio frequency band consistent. The Damping Factor of the power amplifier is The ratio of the rated load (speaker) impedance of the amplifier to the actual impedance of the power amplifier. The large damping coefficient indicates that the output resistance of the power amplifier is small, and the damping coefficient is the ability of the amplifier to control the movement of the speaker cone after the signal disappears. An amplifier with a high damping coefficient, For the speaker is more like a short circuit, it can reduce its vibration when the signal is terminated. The output impedance of the power amplifier will directly affect the low-frequency Q value of the speaker system, thus affecting the low-frequency characteristics of the system. The Q value of the speaker system should not be too high, generally The range of 0.5~l is better. The output impedance of the power amplifier is the factor that causes the low-frequency Q value to rise. Therefore, it is generally expected that the output impedance of the power amplifier is small and the damping coefficient is large. The damping coefficient is generally between tens and hundreds. The damping coefficient of high-quality professional power amplifier can be up to 200 or more. The damping coefficient is one of the specifications of the amplifier. It directly affects the handling of the loudspeaker by the loudspeaker. Generally, the damping coefficient data provided by the loudspeaker only announces the damping coefficient of a certain frequency band. The damping coefficient is very important, it reflects that the amplifier is not affected by the impedance and equivalent impedance of the horn. The ability of a small damping coefficient amplifier is impossible to obtain true high fidelity, especially for speakers with slightly higher sensitivity. Because the speaker with high sensitivity can output a large counter electromotive force when the output of the amplifier is small. The damping coefficient does not represent the damping force. When the horn (speaker) is short-circuited, it has the maximum damping force. It is a finite value. Corresponding to the short-circuit Q of the horn, the larger damping coefficient is only infinitely close to this value. For example, the damping coefficient is 10. It reaches 90%, 100 reaches 99%, and 1000 reaches 99.9%. Therefore, excessive damping coefficient is not necessary. Negative feedback is the decisive factor of damping coefficient. Excessive damping coefficient requires deep negative feedback, which will bring many negative effects. The sound quality of different damping coefficients is different, and can not be explained by the damping coefficient alone, because 99% and 99.9% are in fact no different, more negative feedback processing, deep negative feedback processing is very low Distortion, poor handling brings serious transient intermodulation distortion. The role of damping is to maintain the appropriate Q value of the vibration system, about 0.7-1.0. High oscillation, low, slow motion. See the transition of different Q values ​​of the resonant system. Characteristics, obviously should The appropriate value, not the larger the better. When filtering with large-capacity aluminum electrolytic capacitor, its impedance directly affects the output impedance of the power amplifier, because different capacitor impedances produce different damping on the frequency segments of the power amplifier, which directly affects the sound quality of the speaker. For example, some capacitors have the same capacity but the low-frequency dive is deep and shallow, and the sense of volume is different. Some textures are quite good, elastic, loose and not fat, and not sloppy. The shape of the mid-range is full and solid. It is not hard, the high frequency band is smooth and delicate, the air feel is good, and the analysis power of the silk thread is buckled, but some of them are far apart. In fact, it is easier to change the electrical parameters of the aluminum electrolytic capacitor to suit the sound quality requirements of different power amplifiers. By changing the material ratio and production process, many electrical parameters can be changed to meet different passengers' sound quality requirements, but some electrical parameter changes have a great impact on the life of the capacitor, and the serious life is reduced by 80%, so the electrical parameters are required. To achieve the customer's requirements for sound quality without affecting the service life, in the product design and production, we must improve in many aspects, in order to ensure that the sesame will not lose the watermelon. The same specifications of different electrical parameters of the product for high-temperature load life test many times to obtain results) on the bass and treble can also be used to distinguish between different perspectives, understand the band division to design a suitable product to meet the different customers' requirements for sound quality.
Frequency segments, for example, frequencies below a certain frequency. When these frequencies propagate from this speaker, their spread image is spherical, called bass; from a certain frequency to some frequencies, these frequencies are from this speaker. When they are spread, their diffuse image is hemispherical, called the midrange; from the frequency of a certain frequency and above, when these frequencies are transmitted from this speaker, their diffusion image is conical, called treble; The shape of the sound diffuses slowly into a straight line without spreading, which is super high pitch. The bass and treble can also distinguish the sound into the bass frequency segment, the middle audio frequency segment and the high audio frequency segment according to the human physiological hearing experience, but the frequency. The division of segments is difficult to be consistent, which is generally accepted by most people. According to the language (music) can be stored, the human physiological hearing experience, and the recognized 1/3 octave sequence frequency allocation table, it is recommended to hear The range frequency is divided into the following: 20Hz below--ultra-low frequency; 20Hz~63Hz--subwoofer; 63Hz~200Hz--bass; 200Hz~800Hz--low bass; 800Hz~1600Hz--middle; 1600Hz~4000Hz-- Treble; 4000Hz~12.5KHz--treble; 12.5KHz~20KHz--ultra-high 20KHz or more - UHF; explain the super high and ultra high frequency: super high sound refers to the ultra high frequency that the human ear can hear the sound, these frequencies still have the feeling of "sound". Ultra high frequency -- yes Refers to extremely high frequencies beyond the sense of hearing (above 20KHz). These frequencies have no "sound" feeling and can only measure the existence of frequency.
"Super-high" highlights the characteristics of "sound"; "UHF" highlights the characteristics of "frequency". The difference between subwoofer and ultra-low frequency is the same as understanding the high-pitched, mid-range, and low-pitched sounds. The frequency is the number of sound waves per second. How many times the vibration is called Hertz, in line with Hz, the human ear is not an instrument. It is not easy to accurately judge the frequency, but you can practice slowly. A table, you can make a preliminary judgment based on this table. The frequency band (Hz) hearing sense affects the representative instrument 16k-20k. This frequency may not be heard by many people, so you can't hear this paragraph. Frequency does not mean that the equipment can not be played back. Of course, it does not mean that your hearing is not good enough. Only a few people can hear 20 kHz. This frequency can affect the high frequency brightness and the overall sense of space. People feel a bit stuffy, too much will produce a sense of erratic, easy to produce hearing fatigue. Electronic chorus, Guzheng piano and other instruments of overtones. The frequency of 12k-16k can affect the overall color sense, the so-called "song" of the violin Is determined by the frequency of this segment, this frequency Too bleak will cause the instrument to lose its personality. Too much will produce a burr. In the post-processing, it will be used to embellish the percussion instruments such as cymbals, bells, tambourines, sand hammers, bronze brushes and triangle irons. The high-frequency overtone 8k-12k8~12kHz is the high-pitched area of ​​music, which is most sensitive to the high-frequency performance of the sound. Appropriate highlighting (below 5dB) will greatly help the level and color of the sound, and it will also make people feel high-pitched. However, too much will increase the background noise. For example, the noise of the system (sound card, sound source) will be clearly expressed, and the sound will be sharp and hairy. If this is lacking, the sound will be ineffective. And vitality. Flute, oboe, trumpet, piccolo and other high-pitched instruments 4k-8k this frequency most affects the clarity and brightness of the speech, if the frequency component is missing, the tone becomes flat; if this frequency component is too much The tone becomes sharp and the tooth may appear in the human body. This frequency is usually beautified by the compressor. Some female voices, as well as most of the wind instruments. The penetration rate of 2k-4k is very strong. Harmonic The frequency is 1∽4KHz, so the human ear is also very sensitive to this frequency. If the emptiness frequency component is too small, the hearing ability will be worse, and the voice will be blurred. If this frequency component is too strong, it will produce cough. Feeling. 2~4kHz has a great influence on the brightness of the sound. This sound is generally not suitable for attenuation. This layer has a great influence on the level of music. Appropriate improvement can improve the brightness and clarity of the sound, but there is no way at 4kHz. Excessive protrusion, otherwise the female voice will be too heavy. Part of the female voice, and most of the playing instruments. 1.2k1.2kHz can be a little more appropriate, but should not exceed 3dB, can improve the brightness of the sound, but too much Making the sound hard 1k1kHz is the standard reference frequency for audio equipment testing. The parameters usually given in audio equipment are tested at 1kHz. This is the most sensitive frequency of the human ear. The amplitude of this frequency affects the strength of the sound. If this frequency Fullness, the tone will look strong and powerful; if this frequency is insufficient, the tone will appear slack, that is, the characteristic characteristics below 800 Hz are outstanding, and the low frequency component is obvious; and if this frequency is excessive
The sound of vocals and some percussion instruments 300-500 in the 300-500 Hz band is mainly for vocal (singing, recitation). This band can express the thickness and intensity of vocals, but the vocals are bright and clear, otherwise thin The turbidity. The frequency of the vocal 150-300 affects the intensity of the sound, especially the strength of the male voice. This frequency is the low-frequency fundamental frequency of the male voice, and is also the root audio frequency of the chord in the tone. In the 80-160Hz band The sound mainly expresses the thick feeling of music. If the sound is good in this part, the music will feel thick and emboldened. If this part is good, if it is lacking below 80Hz, it will not even feel the lack of bass. If it is not good. The concert has a dull feeling, even a lack of energy. It is the upper limit of the playback of many subwoofer speakers. It can judge the upper limit of the frequency of your subwoofer speaker. The frequency of male sound 60-100 affects the mixed feeling of sound, which is the bass. Pitch area. If this frequency is full, the tone will be thick and thick. If the frequency is insufficient, the tone will become weak. If the frequency is too strong, the tone will have low frequency resonance and roar. Sense Jue. Drums, timpani, and a few instruments with a very low frequency such as piano, cello, and large. The frequency of the instrument 20-60 affects the spatial sense of the tone. This is because the pitch of the tone is mostly above this frequency. It is the resonance frequency of the room or hall. This frequency is difficult to express. In some HiFi audio, it is necessary to cut off this frequency to ensure the consistency and audibility of the tone. The main parameters of the electrolytic capacitor are:
1. The equivalent series resistance ESRESR is related to the capacity, voltage, frequency and temperature of the capacitor technology'> capacitor. The lower the ESR requirement, the better. When the rated voltage is fixed, the larger the capacity, the lower the ESR. When fixed, the high rated voltage can reduce the ESR. The ESR is high at low frequencies, the ESR is low at high frequencies, and the high temperature also causes the ESR to rise. The equivalent series resistance ESR can be found in the specification.
2. Leakage current aluminum has leakage, which is determined by the physical structure. Needless to say, the leakage current is of course as small as possible. The higher the capacitor capacity, the larger the leakage current; lowering the operating voltage can reduce the leakage current. Conversely, selecting a higher withstand voltage type will also help to reduce leakage current. Combining the above two parameters, it is a simple and feasible method to preferentially select high-pressure varieties under the same conditions; reduce internal resistance and reduce leakage. Current, reduce the loss angle, increase the life. It is really a lot of benefits, but the price will be higher. There is a saying that the electrolytic capacitor works well below the rated working voltage, because it can not be effectively enough to maintain the electrode and electrolyte The depolarization effect will cause the polarization of the electrolytic capacitor to reduce the chopping current and increase the ESR, thus premature aging. However, the premise of this statement is "far below the rated working voltage", combined with some long-term practical experience. It is reasonable to select 2/3 of the nominal working voltage nominal value as the normal working voltage. In amateur case, the leakage current of the electrolytic capacitor can be roughly estimated. The electrolytic capacitor of the same capacity is calculated according to the amount. The voltage is charged for charging, and after a period of time, the voltage drop across the capacitor is detected. The less the falling voltage, the smaller the leakage current.
3. The nominal parameter is the value listed on the capacitor housing.
*Electrostatic capacity, expressed in UF.
*Working voltage (working voltage) referred to as WV, should be the nominal safety value, that is to say, the application should not exceed this nominal voltage. * Temperature is mostly 85 degrees, 105 degrees. Under high temperature conditions (such as pure class A power amplifier It is preferred to be 105 degree nominal. In general, the high temperature coefficient is also helpful for improving the performance of other parameters. 4. Dissipatifactor (DF) Sometimes the DF value is also expressed by the loss angle tan. Is the DF value high? Low, and temperature, capacity, voltage, frequency, etc.; when the capacity is the same, the higher the withstand voltage, the lower the DF value. The higher the frequency, the higher the DF value, the higher the temperature, the higher the DF value. DF The value is generally not marked on the capacitor or the specification. When selecting the capacitor in DIY, it is preferred to select a higher withstand voltage. For example, when the working voltage is 45V, it is not reasonable to use 50V. Although the 50V slave voltage is used. There is nothing wrong with normal work, but there is a lack of DF value. If you use 63V or 71V withstand voltage, there will be better performance. 5. Chopper current Irac chopping current for the filter circuit of the stone machine, Is a very important parameter. The higher the chopping current Irac is, the better. He The height is related to the operating frequency. The higher the frequency is, the larger Irac is. The lower the frequency is, the smaller Irac is. Traditionally, we need to have a high chopping current at low frequencies in order to obtain good high current discharge characteristics. The low frequency is more solid, full and flexible, and has good control drive characteristics; in fact, the high chopping current at the high frequency helps the front of the tone, which can make the high frequency have better extension and reduce the roughness.
Silk fiber
As we all know, silk is made of silk worms. Because silk is an animal product, the main component of fiber is protein. Generally, plant fiber (Manila hemp or pulp) has a cellulose substrate in normal use of aluminum electrolytic capacitors. At the same time, this gives Different shapes and characteristics of different fibers.
For example, when using crepe paper, it produces an exciting sharp, crisp sound. Manila hemp is quieter than kraft paper, but still quite rustling. These sounds are mainly the result of the hardness of the cellulose fiber. In contrast, paper is very flexible from 100% silk fiber, and there is absolutely no hint of rustling.
When we look at the physical properties of these types, the limit of elongation is between 3.9% and 1.9 for cellulose, and the tensile strength is between 4.9 and 6.4 per gram. In contrast, the ultimate elongation of silk is 7 times in 20-23%, on the contrary, the tensile strength is weaker at 3.6 to 4.1 grams per hectare. The silk protein coupling protein is contained in the surface layer called sericin. Because these proteins are mainly derived from glycine. Alanine, a serine amino acid, is extremely simple in structure with other natural fibers. In addition, the fiber surface is smooth in the axial direction. In addition, the fiber has been and well defined crystal polypeptide chains.
As mentioned above, silk is extremely soft compared to cellulose and is very good when resisting physical shocks - in short, silk fibers can be described as "soft"
Sound-improving effect of silk fiber
At Elna, we have advanced the development activities based on the silk point of view, this "soft" can reduce the vibration energy, which is the electrode from the capacitor. At the same time, this silk softens the vibration energy of the music through the air. And compelling capacitors. Ultimately, softness will reduce mechanical vibrational energy from transformers or rotating systems in the final product.
As mentioned above, silk is not mechanically strong. Therefore, we came to a viable product by mixing with Manila hemp fiber. In this mixed paper, silk protein extraction alone in the process of silk fiber beating. Although it is broken down into fine During the fiber process, the silk fiber becomes better and even softer than the individual silk fiber. Therefore, it splits into a slender protein chain.
The virgin fiber diameter is about 10 to 15 μm silk and Manila hemp. The diameter is reduced to 0.2 to 2.0 μm. During the beating process, the blank (about 20 to 50 μm) filled with paper and silk fibers is mixed between the manila hemp fibers (see below). Photo.) From the perspective of vibration absorption, this structure is completely ideal.
Due to the increase in surface area, the interface between the paper fibers and the electrolytic solution are used to drive the device. We have also found an increase in signal propagation speed reduction (ESR). For example, ESRGBL (1khz electrolyte is approximately 20% for a given thickness and density). Less than separator paper by Manila
In addition to electrolytic paper, we use the same materials and conditions to produce a 63v15000μf block type capacitor and a 50v1000μf radial lead-type memory occupying a smaller capacitor. When these are subjected to a high peak in the auditory evaluation range, the mid-range roughness is greatly reduced. , low abundance and power range increase to get high quality sound.
In the "SILMIC" series, we also use the anode foil to grow more uneroded parts and a 55μm low-multiplier high-purity cathode foil in order to improve signal propagation. In the past, using aluminum electrolytic capacitors through synergistic effects and silk characteristics, we can produce a Powerful, yet-mellow, sound, that is impossible.
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