Electron tubes and light bulbs are close relatives.
Please read my early reply:/question/question/8201377.html.
I am a lover of electron tube amplifier, and I hope to communicate more.
There have been countless twists and turns since Edison's time. Not many people have talked about the history of vacuum tubes in this century. Let's try to see its transformation process in this century!
At the beginning of 1880, Edison improved the white light bulb (before that, it was an unfinished tin foil discharge system). Edison made an unexpected discovery in the process of studying the light bulb (he thought so at that time), that is, if an electrode is added to the light bulb and the power supply of tungsten wire is connected, the heated tungsten wire will discharge to the electrode and a current will be generated in the circuit of the electrode. This physical phenomenon is called "Edison effect" today.
The emitted electrons will only flow to the side with high power potential (i.e. electrode), and no current will be generated on the other side. This means that Edison didn't notice this important discovery with rectification function at that time, but only applied for a patent right slightly, so he completely forgot it. Among Edison's many inventions, the invention of scientific principles has only this "Edison effect". After he invented it, he made an amazing discovery that was useless. I believe this time!
Edison had to "entrust" others to invent the vacuum tube, but the phonograph he invented in 1883 was the predecessor of HiFi audio equipment today. As enthusiasts, we deserve to pay tribute to his old man!
1904, Mr. J.A.Fleming, who used to be a consultant of Malcony Company in Britain, invented the diode vacuum tube used in the detector in wireless telecommunications. The original concept of this invention comes from the "Edison effect" invented by Edison ten years ago. He is a consultant of Edison Electric Light Company in London, so he took part in the experiment made by Edison. After leaving Edison Electric Light Company, he continued to do more in-depth research. Fleming named the invented diode vacuum tube a light bulb, or a valve (current only flows in one direction, not in the opposite direction like a valve). At present, the popular name is vacuum tube, which is one thing.
Since then, Fleming bulb has laid the foundation of vacuum tube technology, but it has not been fully applied to radio communication equipment.
Two years later, that is 1906. Forest Company of the United States put an extra grid into the diode vacuum tube, and successfully invented a triode vacuum tube (Orthicon) which can effectively detect and gain. Grid means that the shape of the extra electrode is very similar to that of the grill, so it is also called grid.
Because Fleming claimed that he had the priority of the invention of vacuum tubes, Marcand of Britain also quietly made a triode, regardless of anything. As the saying goes, fat water does not flow outside. Go ahead. American Forest Company was greatly dissatisfied, so it went to court with Marcand Company on the triode issue. This decade-long lawsuit ended in 19 16. The court ruled that the transistor of Do. Forest infringed the patent right of diode, and the transistor produced by Malcony also infringed the patent right of transistor registered by Do.Forest. As a result, both companies lost, and there was no good result. Neither company is allowed to continue to produce transistors.
The court's ruling has greatly hindered the development of vacuum tubes. After the end of the first world, that is, after 1920, vacuum tubes were officially used to manufacture amplifiers.
Before and after the evolution of vacuum tube amplifier in HiFi era
First of all, the use of the word (hi-fi) began in the mid-1930s, during which WE300A of American Western Electric Company and 2A3 of RCA Company appeared at the same time. These two "Weishui" triode vacuum tubes have written a glorious page in the history of acoustics.
WE300A was used to make WE86 power amplifier, which was specially used in talking cinemas at that time. 2A3 is a luxurious "wardrobe" record player installed in RCA-Electroller D22 (automatic record change). Because WE300A is used in professional equipment, most people have never even seen it, so they have no idea about it. This is how 2A3, which is listed in the form of consumer phonograph, is viewed. At that time, many enthusiasts used this power for push-pull amplification and produced a 22-watt "high-power" amplifier, which fascinated the enthusiasts at that time!
1939, in order to get a quieter playback effect of classical music, Columbia Company of the United States took the lead in using master lacquer to carve films. In World War II (1944), Decca in Britain also invented an updated recording method called FFRR (Full Frequency Range Recording). (This recording method evolved from studying the sound resolution method of enemy submarines. The recording frequency should be expanded from 30 Hz to 14000 Hz, which is also the maximum frequency range of 78 rpm SP records. )
On the other hand, the electronic technology invented in the war also developed into the daily use of civilians after the war. 1948, the first LP album was released. Sound technology shines brightly in this golden summer. The first vacuum tube amplifier listed in the United States was launched in the same year 10 after the end of World War II, and the manufacturer was Fisher. As early as one year before the LP analog record came out (1947), the prelude of the HIFI era had already begun. The most striking amplifier circuits at that time included Williamson circuit and Orson circuit designed by Dr. Harry F.Orson of RCA Company who died in 1982 (at the age of 8 1 year).
Golden Age of Vacuum Tube Amplifiers in Europe and America
Williamson amplifier circuit is synonymous with HIFI amplifier at that time, which was published in the April and May issue of British HIFI magazine (Wireless World) 1947. Although it is well known that amplifier circuits add negative feedback (some atomic particle machines add 40 dB negative feedback), Williamson circuits boldly added 20 dB negative feedback at that time, which surprised fans all over the world.
The principle of negative feedback was discovered as early as1August 2, 927. The inventor is Harold Black, a design engineer at Bell Institute in America. He took a cruise ship that day and suddenly came up with the idea while overlooking the Statue of Liberty. He immediately took a copy of the new york time news of the day and recorded the design concept for the first time. But it was not until a few years later, that is, 1933, that the actual research was successful. The amplifier circuit for telephone is 1936, and the output transformer was very poor at that time. Although the negative feedback amplifier circuit is used to reduce the distortion, the distortion is still amazing (compared with the current standard)!
Because the frequency response of the output transformer at that time was not as wide as it is today, although the Williamson amplifier skillfully used the negative feedback of 20 decibels, it was later pointed out by many designers. Even so, the importance of transformer can be recognized for the first time, which greatly affects the subsequent amplification circuit technology. The invention of negative feedback was not in vain! Although Williamson used KT66 tetrode in the power amplifier, the output energy was as high as 10W due to its push-pull connection with the triode.
On the other hand, Orson's amplifier circuit adopts symmetrical arrangement, which connects 6F6 and triode in a balanced way, and there is no negative feedback at all. The design idea of this amplifier is to consider it as a household HIFI amplifier, so as to achieve the best coordination of its frequency response characteristics, distortion, output and production cost, and set the rated range. There is a theory that Dr. Orson does not use negative feedback. Although adding negative feedback can broaden the bandwidth of power amplifier, it will cost a lot of money, so it is not suitable for ordinary household power amplifier. Using triode without negative feedback is a simple and ideal sound effect, which is more suitable for ordinary families!
1949 《 Sound Engineering 》 magazine1February issue, published the Mai Jingtao line for the first time. This line is a single-ended "phase change" push-pull amplifier, which is connected with a 6L6G quadrupole output tube and a specially wound output transformer. This special winding transformer is called bifilar, which can eliminate the cross distortion of class B analog pull amplifier, so it can output 50 watts, and the full-band distortion is lower than 1%. With this circuit, Mai Tao Jing 50W-I professional amplifier is officially listed!
1955 introduced the first amplifier from the same factory, which was deeply loved by enthusiasts all his life. This is MC60, a ferrochrome shell with square fillet in transformer shell. The appearance alone is charming and full of personality (at that time, the amplifier assembled by amateurs only installed vacuum tubes and transformers on an ordinary angular shell). The MC-75, which went on the market later, also used the same circuit. The 60-watt output amplifier of the push-pull amplifier 6550 was replaced by KT-88 (also the first appearance of KT-88), and the output was increased to 75 watts. Later, it was even three-dimensional, and MC275 was released.
Introduction of preamplifier
After entering the LP era, preamplifier came into being. As mentioned earlier, the D22 luxury phonograph launched by RCA in 1934 is not an LP album, only an additional amplifier with a volume expander is seen, but it is not a real preamplifier. After entering the LP era, due to the frequency equalization before engraving (enhancing high frequency and reducing low frequency), the preamplifier is needed to restore (reducing high frequency and enhancing low frequency) during playback. However, the equalization standard of each record company is different, so if the same playback line is used, the playback curve of each record may be uneven, sometimes even the same record, but the playback response curves of A and B are different!
At that time, there were many representative equalization standards, such as AES, NAB, RCA, Columbia, FFRR, CCIR and so on, so the preamplifiers at that time were equipped with selection systems for selecting different equalization standards. It was not until 1955 that this balance standard was unified and became an international standard-RIAA.
The ancestor of HIFI amplifier
1950 years later, various amplifiers were introduced one after another. 1950, Quad in Britain was revived by P.J.Walker, and I-type preamplifier and power amplifier were introduced. 195 1 year, a truly excellent amplifier came out (officially called extended class A amplifier, with four poles and three poles using the same bias, which is a rare class A and class C combined working amplifier). The gate of 6L6 is connected to the top (input end) of the output transformer, which has an ultra-flat linear response. One of the designers is D.Hafler, who founded Dynaco Company in the future. In the same year, Quad also introduced Type II power amplifier. The main amplifier adopts FE86 five-pole tube, and the output adopts four KT66 four-pole tubes. The circuit is simple, the output transformer is made of Quad, and the output is 15 watts.
1955, Petersong and Syncrea of GE company invented a single-ended push-pull amplifier circuit, which eliminated the leakage caused by transformer. Switching distortion caused by inductance. Although this amplifier circuit also uses the output transformer, the workload is greatly omitted, and then it is developed into OTL circuit, so it can be called the prototype of SEPP circuit used by transistor amplifiers today. Speaking of OTL lines, the first OTL amplifier was also launched in the same year, and the manufacturer was Stewarts.
1953, Borgan Amp, White Powerton Amp, Crosschart PP, Multi Feedback Amp；; During the May 4th Movement, countless lines such as straight line, standard ampere, BTL line and infinite negative transmission line appeared one after another. In the same year, Britain's Leak Company also launched a series of "Point One" amplifiers, and the distortion rate was less than 0. 1%, so it was called Point One. At that time, this low-distortion amplifier once became a story! In terms of circuit, it is just a push-pull circuit connected with KT66 and triode, and there is nothing worth mentioning! Marantz, which can be tied with Mai Tao Jing, also introduced the # 1 preamplifier in the same year, and then introduced the #2 power amplifier in 1955 to facilitate the work.
The history of Japanese amplifiers
The so-called "Japanese amplifier" in this period mainly refers to the amplifier made by amateur radio enthusiasts. I remember that the "Williamson" amplifier circuit was first published in the March issue of Radio Technology in the 25th year of Showa (195o). The route of "Mai Jingtao" was first published in Radio Science in August of the following year (195 1 year). That is, it was published abroad for two years before it was recognized by (Japanese). Although we met for two years, the situation at that time was exciting!
In the 26th year of Showa (195 1 year), Japanese Columbia Company released its first LP album made in Japan for the first time. At that time, most technical magazines published some methods to improve the phonograph, and all kinds of HIFI amplification circuits mentioned above were published in magazines in the following years.
In December of the 27th year of Showa (1952), the first All-Japan Audio Exhibition was announced. In the same year, Lux became a hot topic in the field of HiFi electroacoustic with an "X" series vacuum tube amplifier made of broadband output transformer. In fact, as early as before the war (around 1936), Lux Factory had produced a good vacuum tube amplifier of type 753 (output 10 watt, a high-grade courage machine with HiFi tendency). I believe many people can still remember this machine, but in any case, Lux became famous with this high-quality broadband output transformer.
The appearance of vacuum tube amplifiers made by big factories only officially started in the 29th year of Showa (1954). Shanshui pioneered the power amplifier (HF-2A3S) and preamplifier (HRR- 100). Lux subsequently introduced "KMV6" and "KMR5" packaged power amplifiers in the 30th year of Showa (1955). The mountains and rivers are in Tokyo, and Lux is in Osaka. These two factories were located in the east and west respectively. At that time, domestic power amplifiers were divided into two categories, which really aroused great interest in power amplifiers at that time.
We can also guess what vacuum tubes are used in these domestic gallbladder machines just by looking at the models, such as 2A3 of Shanshui, 6AR5 and 6V6 of Lux. In the same year, the pioneer also built the power amplifier HF 10M with 6V6 as the output tube. As for foreign lines, four poles such as KT88, KT66 and 6550 are mostly used, and 6V6 is widely used.
If you look at the price difference of these vacuum tubes, it will be clearer. Based on the market price of 1980, a KT88 costs about 8,000 to 9,000 yen (about HK$ 300), a KT66 costs about 7,000 yen (HK$ 250) and a 6550 costs about 4,000 yen (about HK$ 160). And 6V6 can be bought for less than 2,000 yen (less than 60 Hong Kong dollars). There is a tetrode above, and the triode below is about 8000 yen. As for the "tonic" that is already a "famous vessel", the average price is about 30,000 to 50,000 yen (about 1000 to 1700 Hong Kong dollars)!
As for the power amplifier that was first marketed with this "sound-supplementing" vacuum tube (only one WE300B was used), Osaka's "Stereo Gallery -Q" was introduced in Showa in 1944 (1969), and it is said that the designer was Genji above Lux. However, since then, the rumors of launching the market with 300B have been broken.
Lux is an old brand of gallbladder amplifier, I believe everyone will agree! Even though HiFi has entered the transistor era in an all-round way, Lux has not forgotten the charm of courage machine, and constantly introduced new products of courage machine that win by timbre. In the fifty years of Showa (1975), with the cooperation of NEC factory, Lux produced its own vacuum tubes with unique manufacturing methods and specifications. "6240G" is used for the driving stage and "8045G" is used for the output stage. The power amplifier made of these two "iron guts" is MB3045.
Of course, in addition, Lux has many masterpieces. At first, MA7A of mono was famous for its high power (60 watts), and later it was improved to MB8A, and later it became MB88. In the transitional period of the transistor era, MQ36, an OTL-type gallbladder machine without an output transformer, is one of the many famous devices of Lux.
SQ38 series is the most powerful preamplifier! The 6RA8 and 50CA 10 used in this series of courage machines can be regarded as the "beautiful courage" born in the HiFi era. Lux still uses this 50CA 10 as a negative feedback amplifier (M68C) and puts it on the market.
Each of the above Lux courage machines was made under the guidance of Uehara, completely getting rid of the influence of foreign courage machines and having a unique self-character. In the upsurge of retro courage machine, Lux courage machine really makes people listen very happy! It is said that many new courage machines have been launched. In this digital century, the status of courage machine seems to be increasing day by day.
Electron tube screen
The main materials of low-power CRT screen are nickel and nickel-plated iron, and the difference between different screens is based on this. However, nickel and nickel-plated iron are obviously indistinguishable in appearance and have very similar properties, so there is no need to distinguish them in detail. I think from an economic point of view, most of them are nickel-plated iron. The 6N2 screen that we often see belongs to this material, and so does the domestic 6N 1 1 screen. However, the electric nickel-iron screen of 6N2 6N 1 1 should be finely polished, so it can be seen that it is not extremely bright. The pure nickel screen of RCA 7 1A electron tube is extremely bright, which can clearly reflect the characters. The radiation ability of frosted screen is slightly better than that of bright screen. These screens are all used for low-power voltage amplifier tubes or old large-shell low-power tubes (112171and the like). At the same time, many shielding materials, beam screens and other components are also made of electroplated nickel and iron.
You can see some low-power electron tubes, such as 6F6 (Novosibirsk factory in the Soviet Union). ) is made of off-white metal, which is ground nickel oxide or ground iron oxide. Its radiation characteristics are better than those of the above materials, but it is still not very high. It has been used in low-power pentode 6F6 6K6 and other models.
The 5Z3P electron tube produced by Dawning in 1970s has a shiny black screen, which is a polished and graphite-coated electroplated nickel-iron screen with much better radiation characteristics than a simple oxide screen.
Some imported 6SN7 screens are black matt materials, which make nickel oxide black after high temperature decomposition of hydrocarbons. Its heat dissipation characteristics are better than that of pure graphite polishing, because the working current of 6SN7 is relatively large, but the screen is very small, and the two transistors are in one shell, so it is better to use this material as the screen for heat dissipation.
Ancient power tube panels UX-250, UX-2 10, etc. It is a shielding electrode with filamentous graphite. This material is made by grinding graphite powder mixture, and its radiation characteristics are very good, so it is used to make the screen of advanced power tube. However, due to the complicated process, the electron tubes made of this material are very expensive.
These are the traditional manufacturing processes of electron tube screen materials. After World War II, the material technology advanced by leaps and bounds, especially the application of aluminized iron materials, which completely changed the material of electron tube screen. What is aluminized iron material? At present, most of the electronic tubes we see are made of this material. For example, you have seen the screen electrode of 6P 1, which is coated with aluminum and iron. This material is cheap and has good heat dissipation performance, so it is widely used in electron tubes. Ordinary electron tubes are made of this material. For example, the commonly used radio tubes of 6A26U16K46P16G26Z4 are all aluminum-plated iron screens, the common power tubes 6P6P146P15Fu-76N5P, and the voltage amplifier tubes 6N8p69P16J/. Among the domestic receiving and amplifying tubes, there are some limited tube models such as 6P6P6N26n116E16E2 which do not use aluminum-plated iron screen.
Copper-based Al-Fe coating is a good material for manufacturing power tube screens. Telefunken EL156 EL150 and other famous electron tube screens are made of this material. The experiment shows that the screen temperature of copper-based aluminized iron with the same geometric size is 50 degrees lower than that of carbonized electroplated nickel-iron with the same screen dosage. High-quality copper-based aluminized iron material, similar in appearance to 6P 1 screen material, but obviously yellowish in color. Because the copper content is different, the color is also different. Generally speaking, the yellower the color, the more copper it contains, and the better the heat dissipation performance.
With the continuous progress of materials science, graphite emulsification technology has gradually appeared, and many power tubes have used graphite emulsification technology, such as some domestic models 300B, which are used to manufacture screens.
Another cathode material is graphite. There are graphite cathodes fu521845 in the 75- 100 watt power tube. Some 300B in China are also graphite cathodes. Some people think that the sound quality of graphite cathode tubes is not as good as that of metal cathode tubes, which is totally unfounded. The manufacturing process and assembly process of graphite screen electrode are very complicated, but its effect is very good. Of course, low-power electron tubes do not have graphite screens.
Another problem that needs to be clarified is that some "masters" have heard the hearsay that the so-called new WE300B uses titanium as the screen electrode, which is totally unbelievable. The new WE300B is so expensive that I don't even have a chance to see it. But at present, in many technical materials, there is no record of using titanium as screen electrode. Large and medium-sized launch tubes only use molybdenum as the screen electrode, and spray titanium or zirconium instead of titanium. The screen electrode of ultra-large emission tube is made of tungsten, tantalum or niobium. In fact, titanium is a "toxic" metal for nickel-based oxide cathode, which will lead to premature aging of cathode. Where did the "master" get the news is unknown, and of course it does not rule out material science or at & amp； New progress has been made; T's electron tube factory has carried out new research. So I only study WE300B in theory. If I have the opportunity to see the new WE300B in the future, I can come to the correct conclusion. Judging from the picture, the screen material of the new WE300B is definitely not a novel material, and it should belong to the traditional material. After all, the 300B tube has been finalized and produced for more than half a century, and there is absolutely no need to come up with any novel design.
Through the above, everyone has a general understanding of the electrode of the electron tube screen, and I don't need to say anything else. Finally, it is pointed out that the effect of aluminum-plated iron screen materials widely used now is not worse than that of traditional materials, and it is not the essence to pursue different materials. The problem of sound quality should be solved from the circuit design. As for our use of electron tubes at high frequencies, we don't have to pay attention to these problems.
The structural problems of the screen electrode mainly include the shape and pattern of the screen electrode. The biggest problem is the difference between open form and closed form. For example, the screen of 6N5P is composed of two pieces, so are many 6n 1, but the other 6n 1 are closed screens (made in Shanghai). These problems involve some problems in the calculation of electron tubes and have a certain relationship with the use of electron tubes. I won't go into details this time.
One of the most boring problems is the mesh screen. Some electron tubes have a screen, which is considered good. There are few books on the general theory of mesh screen. Personally, the biggest advantage is that it is convenient to process, and the processing of mesh materials is much easier than that of plates. In addition, I really can't think of any advantages of mesh materials in electrical parameters. However, it is an exception in large launch tubes. For example, the 30,000-watt short-wave transmitting tube of MULLARD Company in the United Kingdom adopts the all-time structure, which is the second-to-none advanced technology before the war, and adopts the mesh tungsten wire screen electrode. Because tungsten can't be pressed into thin plates, it can only be woven into shielding electrodes with tungsten wires, and there is no way. In a low-power electron tube, there is really no need to use this screen. TELEFUNKEN VOLVE TUNGSRAM RFT and other companies have screen rectifiers. If these tubes are really screens woven with tungsten wires, that's really very good, but look at these low-power rectifier tubes. What size screen can dissipate power? Is it really necessary to use a tungsten screen? However, most screen enthusiasts do not seek technical answers. What they need is a little light from the small hole in the screen. I never understood this. If the user really needs the "light" from the filament, how about installing an extra light bulb? It's cheap and much brighter than the stars on the screen.
There are also some experts who don't even know the shielding inside the tube. Yelling at the screen with WE3 10 or EF80 is simply stupid. What is even more stupid is to divide WE3 10 into "coarse mesh" and "fine mesh", and then what is the sound quality of "fine mesh". That's ridiculous.
Technology used to guide the market, but now it is market-oriented technology. Take 300B as an example. When Dawning first copied 300B, it still met the technical specifications. Moreover, in order to improve the performance of 300B, Dawning has also made great efforts, such as developing a 300C electron tube with a graphite screen (filament hook is not improved, 300B can use a coil spring or hook type), and Liuzhou Guiguang has also produced improved models such as 5300 6300, which can be said to be 300. However, the good times did not last long, and a cottage factory in Tianjin came into being. Tianjin s tube 300B was introduced, and electroplated nickel-iron mesh screen electrode 300B came out. These are all gimmicks made by Tianjin Shanzhai Factory. However, Shuguang actually took a lot of "crooked roads" and began to learn to make S-tube 300B, and a variety of screen products came out. Engineers at Dawning won't be ignorant of the theory of electron tube technology, but this is only a market-oriented economy. Making money is the last word, and everything else is redundant. It turned out that Shuguang was still shy and refused to let others know. Now it is completely throwing caution to the wind. ......