"The production of single-tube daring premium, 6h30 amplifier
Keywords: 6h30 single-tube daring front-level production
6h30 This pipe origin is the Soviet Union, and the 6h30 belongs to the frame gate tube, which uses the three-layer mica root bracket to assist the super-strong structure, which highly enhances seismic resistance, and the life is up to 10,000 hours. At that time, it was applied to the fighter "Su-27", which was highly strengthened on the mechanical structure. At the same time, its electrical characteristics were about two parallel 6dJ8 / ECC88, the transconductance is extremely high, the output current is large, the output impedance is low, ultra low Mute, there is almost no microphone effect, a bit like the German root E182CC tube of the same year, as long as it is very simple to play a great performance. Only because of the Soviet military supplies, they will be lifted by the end of 2000, which is known for the group consisting of ambiguous manufacturer and ambiguous enthusiast. The famous ARC in the United States used 4 6h30 in the new Audio Research 3, which is quite index, well known, this Hi-End brand is always dominated by a 6922 / 6DJ8 vacuum tube, from the predecessor Go to the post-level, more than decades is the design of 6922 / 6dj8, now use 6h30 in its top reference series, if the non-performance is excellent, it is impossible to select it. Another well-known brand in China - Osa, in its reference-level Reference CD2.3 advanced CD record system, the RCA output signal portion also employs a buffer circuit constructed by 6h30 as an output. From the above two, you can have an excellent degree of performance of 6H30 performance. Of course, the price of this tube is also relatively high, but compared with the antique electronic tube that is thousands of yuan, the price of two hundred yuan is still very expensive. At present, there is a solid model, gold foot model and EH, which can be purchased in China. There are three types of gold foot models, and the supply is more sufficient, and the quality is also an empirical, which is worth taking a pipe for tapping its potential. Search for circuits about 6H30, the single-tube amplified circuit found two self-sufficient bias, which is loaded with a constant current source; an amplified circuit of Italian enthusiasts, using fixed bias, inductive load Screen output circuit; Diyzone also uses constant current diode to do load test circuit, and found a single tube amplification simulation software for 6H30, which can display the characteristic curve of various work points, which is very convenient when designing circuitry.
Design concept: Preliminary imagustment is a single tube screen output, a self-biased, and the screen is constant. The screen is output, mainly considering that the cathode follower output has no gain, the burst may not be able to explode, and the power of 6h30 cannot be fully exhibited. Although the fixed bias can be flexible to select the work point, it is necessary to add an input coupling capacitor to increase the modified variables of the circuit, and a good coupled capacitor is also worthy of value. The use of constant current sources, one is to help the gain of the child, and the other is to read the Japanese courage book, and the constant current source is used in large numbers in the circuit of Japan's enthusiasts. The total evaluation is a good opportunity. some.
The constant current source has a lot of circuit structures, commonly used aspects: constant current diode, field effect tube, LM317, light-emitting LED (diode, TL431) and crystal triode, op amp, and crystalline triodes, tubes, transistors and tubes, Field effect tubes and mixing use of tubes, integrated circuits, and tubes are limited to space, which is not described in detail here. Considering the high voltage required to bear the 6h30, it is desirable to increase some of the five-pole-specific exhaust, because it has seen the foreign national design circuit, it is 6080 to make a single tube line, EL34 is constant Flow source, the original author believes that the frequency response of the triode is relatively straight, and the high and low end extension is better. The sound of the five-pole is condensed, analyzed, and the two characteristics should be a perfect sound. A constant current source circuit composed of 6bq5 (6P14, EL84) is prepared by this article.
Jobs Mr. Li, who just got a Taipei, Mr. Li, who had already been a maintenance member of ARC Taiwan agent, has three or forty years of maintenance of the top audio equipment, and the ARC common preamps and posts It is very familiar with the power amplifier, and he talks about 6h30. This is the idea. He quickly draws a 6H30 and 6BQ5 combination line to enlarge circuit diagram, see Figure 1, of course, this circuit is strict, it is not a constant The stream source, but a variant SRPP structure, since the gate of 6bq5, the cathode is connected to the 6H30 screen, when it is 6h30 input AC, its power is changed, the 6bq5 operating current will also change, belonging Asymmetric impedance SRPP circuit, since the upper and lower impedance is different, the midpoint output is not half the voltage of the B + voltage, and the maximum output clip is not a top and down, so it can only work similar to SRPP.
The initial setting of several resistances in the figure: first set the working voltage of 6H30, according to the original data of Figure 2, decide to adopt the following work points: screen voltage: 150V, gate voltage -9 V, screen stream: 20mA, by simulation software: The magnification coefficient of 6h30 at this time is μ = 15, and the transconductance GM = 9.58. Calculate the cathode resistance: 9V / 0.02A = 450Ω, take 470Ω1W. At present, the output level of the CD machine is generally around 2V, so the general gate bias is 1.5V, and the 6H30 is trying to attempt to attempt to work in a large current operation. The characteristics of the sound, so the gate electrical pressure is taken -9V, so although there is a certain drop in the match with the output swing of the CD, the loss point is magnified, but the input signal dynamic range can be made in communication. The distortion is smaller, and the improvement in signal waveform is greater than the disadvantage. The screen pressure is also taken, the maximum signal amplitude of the output can reach 50V. Look at 6bq5, the Class A is magnified, the screen voltage: 250V, curtain gate voltage: 250V, cathode resistance: 135Ω, screen stream: 48mA + curtain gate 5.5mA = 53.5mA, now change to 20mA, now the cathode The resistance is: 53.5 / 20 × 135 = 361, actually use 320Ω1W. The specific values are also adjusted in practical production.
Production and debugging
The chassis border is bent with the renovated aluminum profile. The upper and lower cover uses a 2.5 mm aluminum plate. It is easy to process with the opening of the tube hole, but pays attention to the two points for the initial use of life, the first is To open a positioning hole of 3 mm, it is not possible to open the hole, which is easy to get the aluminum plate. The second is to drop some oil or sewing machine's lubricant when opening, so that the edge of the hole is very smooth. The nine pedigrees should use a 6-diameter open device.
The chassis is finished. For the sake of beauty, use black self-painting color, and the paint film can be fixed, the switch, indicator, power socket, RCA seat, see Figure 3, then fixed the power cow, the tube, the electrolytic capacitor card And inside the terminal.
First weld 220V AC power cord and switch. Then, the wire connection portion of the flow tube, 6h30, 6p14 is then welded.
The filament of the 6h30 is 4, 5 feet, and the ground can directly put one of the 4 or 5 feet, if there is communication noise, you can also try to use two 10 to 20 Euro resistors, soldered in 4, 5 feet, and then put The two resistors are sold to a common ground together.
The 6bq5 filament is two parallel, floating, is only one set of communication 6.3V, not grounded, wait until the power is transferred, measured the cathode voltage of 6bq5, with two resistance divisors, slightly higher than the cathode voltage Can.
After the welding, first power supply test voltage (at this point should pay attention to the connection of the high-voltage terminal of the power transformer, you can use the insulation tape to avoid dangerous electric shock), normal, you can plug in the whole flow tube, 6p14 and 6h30 tube , Power-on test, the filament voltage is tested again, and if the voltage is accurate, and the tube is normal, it means that the filament power supply section can work normally, it is necessary to explain, during the day and night, because the power supply is different from the power grid is different, so The city's electricity will float up and down at 220V because the filaments are powered power supply, so the fluctuations in the main electricity are considered when the filament is checked.
Fixed high-voltage electrolysis and choke, welding, inspection, check, check the power-on test, pay attention to the high voltage portion must be welded to the discharge resistance and then inspect, otherwise, the chassis is relatively small, it is very small It is easy to hit by high voltage electrolysis.
The power supply is correct, and the welding circuit can then be placed in the welding circuit. It is very simple to enlarge. Note that the component pin should not be solder. After welding, insert the tube, you can initially test it.
When the power is turned on, the tube filament is slow, and the circuit can be tested. When the test is detected, it is found that because the 6H30 tube current is large, it is simply via the CLC to regulate, and the effect cannot meet the requirements. The manifestation is shorter, and the alternating current noise voltage of the output is high. Test 20 mV with DA16 millitentolic meter. Helpless, the original program has to give up.
Since the chassis opening has not changed, it is intended to change the original electronic pipe rectification to a transistor rectification, so that the output voltage can be increased, and the original rectifier position plus 6N5 as a power adjustment tube. This gourd tube is very beautiful. The power supply portion is changed to process production with rivet soldering sheets and wires on the epoxy plate. Pain your sketch on paper, lay the position of the component, in order to seek the best wiring plan, foot foot is spent for a long time to determine the final program. Open a good hole overnight, the next day, the time is set to install the rivet. Prepare the welding assembly.
When preparing the assembly in the control circuit diagram, it is just to see Mr. Li, Mr. Li, found that a key issue is ignored, that is, 6N5 to adjust the tube, to satisfy the voltage drop of 60 ~ 90V, so although the transistor rectifier output voltage increases. However, the last output voltage can only be around 280 to 290V, and the 350V voltage requirements required for line amplification requirements cannot be met. Helpless, just made a good board has to be abandoned, and now you have to select the transistor, field effect tube or LM317 to do a regulated power supply. Thus the original installation of 6N5 is empty, two processing methods, one is to find a heat sink, on the hole cover, and the heat sink as a transistor. Second, install a voltage amplifier tube of a big eight foot, a voltage amplifier of a regulated power source. I remember that the "High-Financial Sound" magazine has been introduced in the article, and there is a soft start-up function. However, here, the interference problem of the AC filament is considered, and it is better to be a better way, so it is re-started. Arrange part of the part. Hey, this 6h30 is really not waiting!
The third power board adopts the simplified board of the Mades power supply. The circuit diagram is shown in Figure 4. This circuit has been very good. It has been doing more than a dozen pieces to a friend. The exchange ripple voltage is only 0.1mv, no wonder Hong Kong and Taiwan enthusiasts. It also uses it, which is used here. It is used in the shed welding. The wiring of the main filter portion is shown in Figure 5. The main regulator portion is shown in Figure 6, first fix the MJE13007 and LM317 to the heat sink, pay attention to install the insulating gasket and insulating sheet, installation On the casing, because the components are small, the welding is fast.
Power-on, output voltage 350V, look at the waveform of the power supply voltage, a horizontal straight line, indicating that the stable power supply is good!
The installation of the internal power board can be found in Figure 7, the original plan is used to balance filtering, but since the voltage drop is 20V due to the full load of a choke, is limited by the output voltage, 390V-20V-20V = 350V, unable to meet the input voltage requirements of the voltage regulator, have to change to a single clef.
Measurement of the operating point: The voltage of each point is shown in the figure, the B + 348V, 6H30 on the ground voltage 170V, cathode voltage: 9.2V, calculated the screen current IP = 19.6 mA. Basic and design work points anastomosis.
Converse the input, then observe the oscilloscope on the output, almost one horizontal line, test with DA16 millitentolic meter, 5mV, still some effect, considering that the capacitance of the output is open, if the load is connected, the estimated noise voltage is also It will be reduced, so it can be considered that it is basically satisfied. Making the aspiration of the like, there is a lot of convenience, sometimes the circuit is high frequency, no oscilloscope is difficult to detect, and now the second-hand 20m is more than 3, 4 yuan, and there is a condition or should be prepared.
There is also a small episode, starting the second-hand EH gold feet 6h30, found that the left and right channel voltage of 6h30 is 20V, replacing a new 6BQ5, still, changed the new Sovtek brand 6h30, test discovery voltage The difference is less than 2V, it seems that if it is required, the tube of 6h30 is also needed to pick it up.
The work point of the circuit is basically normal, and the next step can be adjusted to the front-level sound, which is relatively simple, and can be carried out by a little adjustment of the operating point and replacing the output coupling capacitor. For friends who just contact the inverse machine, the 6h30 screen load can also test several forms, such as resistance, inductance, constant current source, etc., and the second to increase some inductive understandings.
Because of the pipe, the blocking parts are new, so the aging will be energized for a while. If there is a saucer, you can try it.
Some of the following tubes were listened to the actual test:
6h30: Sovtek ordinary, EH gold feet
Active load: Beijing 6P14, Dawn EL84 / 6PQ5.
The sound source is the old disc server installed the PCM1716 decoding board, and many times, the sound is still satisfactory. The speaker is a small box made from Fostex's FE126 full-frequency speakers, and the sensitivity of the speaker is 93dB. The amplifier is used by the LM1875, the wiring form of the power amplifier plate PCB refers to an improvement plan on the April 2007 magazine 2007, the signal-to-noise ratio is up to 105dB, which is very suitable for the promotion of the high sensitivity of Fe126.
As for the specific sound performance, because of the equipment, the pronunciation environment is very large, not much narrative, the initial feeling is relatively atmospheric, it is worth further detail. After a long time, I feel that the feature is fast, low frequency feeling, but there are less chanting, more straightforward, and then consulted Mr. Li, for Mr. Li, according to Mr. Li, put 6h30 The current is small, 470 Euro change to 560 Euro, 320 Euro to 420 Europe, the output of 0.33 microcontroller is connected in parallel with a 0.022 microcomputer, slightly improved in the high frequency, to seek the balance of listening After such adjustment, the sound has a significant improvement, and now use this configuration first, and later there is a better solution, and report to you. "
Our other product:
