In 1904, the birth of the tube device (also known as the vacuum tube device) brought a revolution to the traditional audio field. Today, the tube still has a special status and unique application, and is affecting the PC multimedia audio field because it Many of the characteristics are not found in transistors.
As a kind of "voltage" amplifier, the working principle of the current amplifier is the same as that of the transistor. The signal distortion characteristic of the tube is much larger than that of the transistor. The even harmonic distortion of the signal in the tube amplification circuit is large, and the odd harmonic distortion is small. The transistor is just the opposite. The tube amplifier circuit has a relatively high overload capability. When the instantaneous peak value of the input signal is overloaded, the tube does not appear to be clearly clipped, but only the tip of the peak is rounded. Such a smoothing effect can maintain the signal. Relative integrity. In contrast, the transistor will appear to be directly clipped.
When the transistor is used beyond the limit parameter, it will be damaged in an instant, but the tube can work normally and has little effect. The input and output impedance of the tube are relatively high, and the high input impedance indicates that it has less influence on the front stage and can be better. The operation state of the pre-stage circuit is guaranteed; the high output impedance is not a good principle from the circuit principle, because it requires a transformer to perform impedance transformation at the power output, which causes the cost to rise, but the presence of the transformer is good for the tone. This is pure Technical analysis, of course, tube amps and transistor amps are very different in terms of sound performance.
Amplifier and transistor machine
Speaking of the difference between the cost and sound quality of the amplifier and the stone machine, if the price is less than 1,000 yuan, the amplifier can not be produced at this price, and people can not buy a good amplifier product at this price. Although you can buy a crystal machine, it is difficult to buy a good product. In terms of sound quality, generally the amplifier with the same price below 30,000 yuan, the sound quality of the amplifier is usually better than the crystal machine; in the 30,000-50,000 yuan At the price level, there are different advantages; at more than 50,000 yuan, the crystal machine generally has a comparative advantage. The crystal machine with a price below 50,000 yuan is generally superior to the brightness of the bass, the speed, and the brightness of the treble. Outside the amplifier, it is difficult to compare with the amplifier in terms of sound quality, tone, music and hearing resistance. This is the common understanding of many enthusiasts through practical experience.
Domestic amps and foreign amps
The start and history of foreign amps are far more than domestic. Besides, the amp products have a certain artistic and very strong cultural background, which is mainly reflected in the product sound adjustment, brand positioning, market strategy, design, product quality. Stability and other aspects. It should be said that compared with some foreign excellent brands in these aspects, our domestic brands still have a certain gap with them in some aspects, but after several years of efforts, this distance is gradually narrowing. Compared with foreign brand-name products, some of the better products made in China are much stronger than them, and domestic brands have great advantages in terms of price. On the same level of products, the price of domestically produced machines is at least 1/% lower than that of imported machines. 5-1/2. Nowadays, the individual products of domestic brands are even worse than the sound quality of some famous brand products at a lower price. This is not a strange thing. Domestic products The direction of the effort is mainly to establish brand awareness, and to improve product quality and artistic level.
About the shape of the amplifier
Most of the shape of the amplifier is to expose the components of the tube and transformer to the outside of the casing, which is different from the box machine in the traditional concept. However, it is not the case that the amplifier must be made into a box. In fact, now Some of the amp products have been made into box machines, but the traditional sculpt is related to the psychological aesthetic concept of designers and users. The design of modern amps is like industrial art design, paying attention to fluctuations, color contrast, bright lines and The embodiment of the use of materials.
A fine tube amp modeling and processing are like a work of art, box-type machine visual expression in these areas are more difficult, relatively speaking, the free space on most of the bare metal. Tubes when Danji work to the filament When it is lit, it will give people a sense of warmth, and the box machine will look colder than it. There is no "bare machine" kind of "human feeling", which is one of the reasons why bare metal is more popular than box machine. The bare metal can also better reflect the characteristics of the amplifier. Although the bare metal is often not convenient in the use of the box machine, it is more difficult to "serve", so there is a situation where the bare machine and the box machine coexist. In terms of proportion, the bare metal in the market The number is much larger than the number of box machines.
Amplifier technical indicators and standards
In addition to the static intermodulation distortion, the technical specifications of the amplifier are not as good as those of the crystal machine, but the survival and development of the amplifier is not because of its technical indicators. Technical indicators, the amplifier has long been out of the market. In fact, electro-acoustic technology is still very imperfect, the existing technical indicators can only explain the problem from one aspect, but can not reflect the problem in essence. For example, the measurement of existing amplifier indicators It is measured under the assumption that the load is purely resistive (linear) load, and the actual load is a complex resistive (non-linear) load. For example, the measurement of the speaker is measured at a distance of 1W and a power of 1W. The actual listening can not be 1 meter / 1W, so such measurement indicators can only be used as a reference, but not as a standard for selecting amplifiers.
A product with good technical indicators may have a bad sense of hearing, and a product with a good sense of hearing may have a flat technical indicator (of course not bad). A mass-produced electronic product must be guaranteed. Its uniformity and consistency must have a corresponding production standard (technical documents, production process documents and inspection documents), which is common in the production of some more formal products, but these standards only guide production and To ensure the consistency and uniformity of product quality, and no other meaning. A company's production standards are only useful for the specific products of the company, but not useful for other companies, and the meaning of the product's artistic and sound quality is not meaningful. There is no standard measurable for art. In reality, the higher the level of audio products, the less stringent the production standards are.
About single-ended and push-pull
In the final stage of the amplifier, there is a push-pull operation method, and a single-ended operation mode is adopted. Since the push-pull method is relatively easy to obtain high power, this is a circuit form which is very common in a amp, but Push-pull work is a superposition method, so there are some distortions objectively, and there are additions and subtractions in the push-pull stack. In this addition and subtraction, some small things that were not originally added may be added, and subtracted. There are some small things that were originally there. If the single-tube is used in the single-ended class A state in the final circuit, there is no problem that is easy to occur in the push-pull mode.
Therefore, single-ended is much better than push-pull on the sense of hearing, especially in the small details of the sound. However, it is difficult to make a large single-ended power, such as using the same type of tube, at the single end. It can only be 10W, and it is easy to do 30W in push-pull. It costs a lot of power when it is big. At the same time, in the process, single-ended machines are more difficult to handle than push-pull machines. Therefore, single-ended circuits tend to Used in high-end machines, push-pull circuits are used more in popular machines.
The difference between the different methods of the electron tube in the final stage of pushing the circuit
The tubes used in the final stage push-pull circuit are often quadrupoles and pentodes, so there are three-stage tube connection, super-linear connection and standard connection when using these tubes. The difference between them is theoretically The triode connection distortion is the smallest, the output power is also the smallest; the distortion of the standard connection is relatively large, and the power is also the largest; the super linear connection method is somewhere in between. In the sense of hearing, several connections have their own merits, relatively speaking The triode connection method is slightly better. However, the triode connection method is less used in industrial production because of the loss of the life of the electron tube .
Push the effect of the circuit on the sound quality
Generally speaking, the driving circuit and structure have a great effect on the orientation of the sound quality sound. In the low frequency intensity of the sound, the medium and high frequency speed sense and the medium frequency density sense can all obtain different effects by pushing the different circuits. There are many kinds of it. It is difficult for the average person to judge the quality of the product from the difference of the driving circuit. What kind of circuit is chosen is a choice of the designer's tone orientation.
Different types of tubes have an effect on sound
The electron tubes commonly used in the pre-drive circuits are ELF82, 6F1, EF86, 12AX7, 12AU7, 12AT7, 12BH7, 6DJ8, 6SN7, 6SL7, 6SJ7, 6N1, 6N2, 6N3, 6N6, etc. In principle, these tubes may be used in the amplifier. Make a good sound, but each model has its own characteristics, the designer will decide which model to use based on many factors.
In general, ELF82, 6F1, EF86, 12AX7, 12AU7, 12AT7, 12BH7, 6DJ8, 6SN7, 6SL7, 6SJ7 are the most commonly used electronic tubes in foreign countries, and many manufacturers have production, so the interchangeability is better. Commonly used in the machine or foreign machine. The commonly used electron tubes in the final circuit are: KT88, 6550, EL34, 6L6GC, 2A3, 300B, 211, 845. The first four tubes are hot-type quadrupole or pentode, often The power is used in the push-pull circuit; the latter four tubes are direct-heating transistors, and more are used in single-ended class A (2A3, 300B are also often used in push-pull circuits).
Relatively speaking, the sound of a direct-heating triode is slightly better than that of a hot-type quadrupole or a pentode. However, it is also a triode or a quadrupole. Each model has some differences in sound quality and its own characteristics. Because the amplifier is a plug-in device, it is convenient to directly replace, so the change of the game machine has become a great pleasure in the use of the amplifier.
The output transformer has a great influence on the tone.
The output transformer has a great influence on the index and the sense of hearing of the whole machine. Now the frequency of the excellent push-pull output transformer is 10Hz-1O0kHz, and the distortion is below 1%. There is no problem at all. It can be said that the transformer is not currently The key components affecting the indicators of the amplifier. But the structure, process and materials of the transformer have a great influence on the sound of the whole machine. In fact, after the index of the transformer exceeds a certain range, it is not the higher the index, the better. If the amplifier There is no output transformer, such as OTL, its sense of hearing is different from the traditional amplifier. Therefore, the tone of the amplifier is closely related to the output transformer.
About Combined Amplifiers and Front and Rear Amplifiers
The combined amplifier has the following characteristics: (1) When the signal source is at a certain input level, the output of the amplifier can reach full power (2) The amplifier has multiple sets of source input selection (3) The amplifier has level control function (4) The left and right channels are integrated into one, and can also be equipped with high and low tone control devices. In the early days, the output level of the signal source was relatively low, generally around 0.2V, so the input power of the combined amplifier should be below 0.2V on average. Modern signal sources have undergone great changes. For example, CD players have been widely used. The output power of modern signal sources is between 0.5-1V, so the input sensitivity requirements of modern amplifiers have changed accordingly. Of course, no matter how it changes, as long as The first three of the combined amplifiers are the combined amplifiers.
The front-end amplifier is a one-in-one combination of source selection, level control, and voltage amplification (the active preamplifier with voltage amplification, and the passive preamplifier if none). The pure post stage is to amplify the voltage and Power amplification is unique (or two-body), with one input from left to right, no level control and source selection (input level between 1-2V). This method can be used in structure, distribution and materials. Reasonable, so the front and rear split-type amplifiers are higher than the combined type in the grade, and the price may be more expensive.
About the service life of the amplifier
Compared with the crystal machine, the life of the tube is in principle semi-permanent. The relative life of the tube depends on the life of the tube . The theoretical life of the tube is not too long, generally only thousands of hours, but a good tube It is also very common to use tens of thousands of hours. For example, the CRT TV picture tube is a special type of tube . Of course, many audio tubes cannot be compared with the life of the picture tube. Generally speaking, the sound tube has two kinds of transportation failures and early failure. The failure can be found within 1-2 months after use, or found in factory production. For a more stable electronic tube , use 2-3 hours a day. It should not be a problem for 2~3 years.
Besides, the current electronic tube is not expensive and not difficult to buy. With good after-sales service, the service life of the amplifier should not be a problem, and the new vitality can be re-energized after the gallbladder is changed, just like the new machine. In fact, now Many antique amps are also sold at high prices in the market. Doesn't the life of the amps be explained from the other side? The ratio of the amplifier to the crystal machine is relatively high, and the crystal machine may be in the case of some failures. One second will be damaged, and the amplifier will not be damaged within a few minutes.
Precautions for using the amplifier
1. Before connecting the power supply, connect the load (speaker) first, and avoid sending the signal after the power is turned on without connecting the load, or the load is short-circuited.
2. Do not use the power supply too high or too low, the power supply voltage should be within 5% of the specified voltage. It is best to use the AC regulated power supply when the mains supply often exceeds this voltage value.
3. When the tube is working, the temperature is high, and the ventilation and heat dissipation should be placed.
4. Do not sprinkle liquid on the tube during the startup or just after the shutdown (within 30 minutes). Generally pay attention to the above problems during use, the amplifier can work reliably.
Matching of amplifiers and audio-visual equipment
It is very important to use a pair of speakers with a pair of amplifiers, but it is difficult to find a matching principle. Generally speaking, it is best with the British box and the European and American speakers with a sensitivity of over 87dB. For example, HARBETH, ROGERS, SPENDOR, PROAC, B&W, KEF in the UK , TANNOY, TDL, EPOS, MISSION; France's JMLAB; Italy's CHARIO, SOUNS FABER. Some low-sensitivity small speakers are also very good with the amplifier, such as: LS3/5A, PROAC TABELETTE III; others have high intensity The horn box such as ALTLCKLIPSCH, WESTLAKE, etc. also has a special charm with a small-power single-tube type tube amplifier. The domestic box can be selected with some models of "beautiful sound" and small whirlwind. The speaker is matched with no experience. You can find some examples that have been paired or actual match and then confirm.
Introduction to ten EL34 tubes Â
The EL34 amplifier is quite popular among many enthusiasts. Compared to the KT88 and 300b tubes, the EL34 looks very thin, but the EL34 sound is loved by many enthusiasts. There are many kinds of EL34 tubes available on the market. Will introduce you to the common ten EL34 tubes .
1. Domestic dawn EL34B
Twilight's EL34B is a new tube made by Dawning. The price is about 45~5O yuan. The sound is very thick in the medium frequency and the low frequency is good, but the sound is rough and the analysis is not high. It is said that the early domestic EL34 is very good.
2. Spock with EL34
This is the original EL34 tube of MT-35. In fact, it is also the domestically-produced EL34B. It is only made for Spark. It is printed with the trademark Cayin. The overall performance of this tube sound is similar to the domestic EL34 mentioned above. Therefore, users do not hold too high expectations for the tubes that are randomly attached to the factory machine, but it is not a problem to satisfy the average user.
3.Russia EH EL34
This is a new modern Russian tube, the price is about 55-65 yuan, the sound is very beautiful, the low frequency is very powerful, the resolution is good, the sound lines are slender, but the sound is more like the style of the stone machine, the lack of music is not wide enough. The high frequency is too bright. And its performance on the single-ended class A circuit is better than the push-pull, the sound is warmer and more lubricated.
4.JJ blue glass EL34
Czech JJ's EL34 has several kinds of white glass, red glass and blue glass. It is said that the sound of blue glass is the best, especially the dynamic and sound density are better than white glass and red glass. The price is about 150-17O yuan. JJ's EL34 sound is very active, the music is strong, the sound density is high, the mid-range and low-frequency performance is very good, the high frequency is very smooth, the whole is a bit like the style of Amperex pipe. But the high frequency performance is a bit gray, the extension is slightly worse One thing, if you put this tube on a single-ended class A circuit, the high frequency will behave more gray.
5.Ei EL34
This is the EL34 made by the Eiira Ei factory in the 1970s and 1980s. It has a special shape. The top has a pointed top like a small nine-legged tube. The price is about 110-130 yuan. Its overall performance is very Balance, the sound is a bit slow, the sound is more delicate and noble, the music is good, but the low frequency control is a little bit smeared, the sound field is slightly worse than JJ.
6.Ei 6CA7
This is also the 6CA7 made by the Yugoslav Ei factory in the 1970s and 1980s. It has the same shape as the Ei EL34. It has a pointed top, but the figure is much thicker than the EL34. The price is about 170-190 yuan per piece. Its performance is Fast, dynamic sound field and music are good, low frequency dive deep, medium frequency thick, vocals are very soft and sweet. This 6CA7 overall performance is very good, but the high frequency lines are not fine enough, lacking the feeling of cohesion. But when buying this kind of pipe, it is best not to buy it without testing or second-hand. It is recommended to go to the credit merchant to test the pairing and buy better.
7.TESLA EL34
TESLA is also the predecessor of JJ. This is the red tube TESLA EL34. The overall sound is similar to JJ's EL34. The sound balance is delicate, the high frequency lines are very delicate and accurate, the music and low frequency are better than Ei's EL34, very Mullard's Style, dynamics and scenes are not as good as Ei's 6CA7. But this TESLA tube is also hard to find, it is said that one has sold more than 300 yuan.
8.Siemens EL34
This should be the product of Siemens in the late 1970s. The base is bigger than the average, and the size is higher than the average. The EL34 of Siemens is characterized by extremely fast speed, very large dynamic, very high analytical power, low frequency and high frequency. The frequency is very fine. The disadvantage is that the music is not enough, the vocals are a bit thin. This tube performs very well on the single-ended circuit, the sound is quite satisfactory, and the music is obviously much better.
9.MuIlard EL34
This is Mullard's second batch of double-circle deep-skinned EL34 in the XF2 delivery period of the 1960s. It has the style of Mullard. It is a typical British sound. The music is very rich and intoxicating. The sound performance is very balanced and delicate. Gorgeous but not too radiant, medium frequency is soft, low frequency is thick, but the sound is a bit slow. Mullard's EL34 is very difficult to find now, even if there is, the price is also high price, a set of NOS is estimated to be more than an MT-35 It is expensive.
10.Telefunken EL34
Although it bears the trademark of Telefunken, it can be seen from the structure of the pipe and the code XF2. In fact, it is the first product of Mullard's XF2 delivery in the 1960s, which is one time earlier than the production of Mullard mentioned above. A little bit. The difference is that the 8 feet are all aligned, and only the 7 feet of the second batch of the Mullard XF2 delivery are all the same, the other structures are the same. In fact, in the production era of Mullard's XF2 delivery period. Mullard occupies almost the entire EL34 market, and the code number has risen from the 3 digits of XF1 to 4 digits with a lot of production. Its sound is generally similar to that of Mullard, but it feels more dynamic than Mullard. It is said that the EL34 of these two periods is the most balanced product of all the Mullard EL34 in terms of sound performance.
Music enthusiasts are like this, they just like different sounds, and the amplifier is just so fun. You can change one or two tubes to become another sound style, but the key is to adjust the taste of each person to adjust. Play different Types of music choose different tubes, which is also very fun, but these are always tools for replaying music. Listening to them more, retrieving the music itself, too deliberately pursuing a certain effect and ignoring the music. The essence is not interesting.
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