Hetian Mao's front-level production, Vacuum Tube Preamplifier
Keywords: tube, amplifier, front
Producing a good premium, it is more difficult to make a good post-level, which is difficult, and the pre-serial amplifier has high signal to noise ratio, the pre-high-level amplifier of the high letter to noise can make People have heard more details, making the sound field more accurate, the air and the sense of appearance are better, so the signal-to-noise ratio is an important indicator of the pre-queen amplifier. Good circuitry must have a good component and reasonable assembly process to give full play to the advantages of the circuit and minimize noise and distortion. This line is enlarged by the two-stage pure Class A to enlarge the first-level common screen co-yin output mode. Its two-stage co-levels of 6dj8 in front of its lines are large. The output stage uses SRPP mode, but this SRPP method is not in the same place to take the cathode and the anode of the cathode and the anode of the tube. Cathode resistance. Unlike the general voltage amplification, the third level SRPP output stage does not have any voltage amplification. Only a buffer stage for reducing the output impedance and increasing the output current, but the drive load can be stronger than the ordinary cathode output. In the overall line, in order to improve the details of the music, the electrical energy indicator of the machine is improved. The machine uses the appropriate loop negative feedback to reduce the output impedance, and the overall frequency response is lower than the distortion. It can have such an excellent overall performance, I believe that its last level special SRPP cathode output line is the essence of the entire line. The dynamics and high frequency response of this line is better than the M-7, and its analysts and signal-to-noise specific are extremely high. Its route is as follows:
This line is a bit different from the original and Tianmao line. The first level is more than a 100V voltage regulator. It is mainly determined by the working voltage of 6dj8, and it is more stable to ensure that the voltage fluctuations can be stable. Work, the most important thing is the difference in the output, and the output will have DC potential output when making the output, and there are many inconveniences in use. There is a small amount of capacitance, it will be better. Is the sound good? It is also necessary to pay attention to the safety of the equipment. The figure below is the original and Tian Mao line chart. This line can be improved on the image to add an output capacitor at the output. Everyone can compare.
Figure 2 Original and Tian Mao line diagram
Component selection: The resistance is used in the domestic metal film five-color ring resistance. (This machine is a feek, and all habits that have a mock machine. If he feels not enough to burn, let him play) because of the experience in Mosbark 110, so the coupling capacitor is selected. When used back to RIFA and WiMA capacitors, the Rifa capacitor sound is relatively sweet, and the intermediate frequency is better. The special product of WiMA capacitors is fast, and it is relatively transparent. The intermediate-stage transportation capacitor, the bypass capacitor of the SRPP output stage high voltage, and is the RIFA capacitor. The feedback capacitance and output capacitor use WiMA MKP capacitance. Filter capacitors at the foremost level I changed to the 250V10U MKP capacitance with ERO. This is not to say that it will be better to change to the MKP capacitance, because the price of the MKP capacitance of the local high-voltage electrolysis and the MKP capacitor is similar, so the MKP capacitance is used in psychological effects. The potentiometer uses a domestic skewer step-grade potentiometer (30 yuan), some people ask me why I don't have to use ALPS potentiometers, ALPS new iron shell potentiometers (about 90 yuan), much more than before. I believe that many enthusiasts have seen the previous Alps shell potentiometer and the current ALPS ferrper potentiometer, which can be compared. The previous iron shell is more than twice as the current potentiometer. It is not to be sealed with aluminum, but a small piece of aluminum sheet is used in the upper and lower covers. What have the previous weight be more than the current weight? The 60 yuan ALPS potentiometer is actually those ordinary ALPS potentiometers plus a plastic shell. Potentiometer is unbalanced. The NOBLE potentiometer is relatively expensive (around 180 yuan). At the time of trying a domestic step-level potentiometer, it is very good to have a good balance. Everything has the first time. This time, when testing the quality of the domestic string hind-level potentiometer? (The only concern is that the contact is silver-plated, and it will not be ...) The ELMA grade in Switzer is good, but because the price is too high (2500 yuan). Let's buy one trial after you have become a rich person! ! !
One of the best volume potentiometers in sound quality, British Penny + Giles RF-15 Series
The Swiss ELMA grade input potentiometer is in the production of mandate, whether it is reasonable for the layout. I have always thought that if there are various wirings in the machine, there is a feeling of comforting people's visual and auditory. I don't like the wiring in the machine, chaotic, and long wires turn right in the interior, give people a confusion. Otherwise, it is said that "the artillery" earthwork bubble is also. It is actually to reflect a person's understanding of the sound art, reflecting personal style and production spirit. Good circuitry must have a good component and reasonable assembly process to give full play to the advantages of the circuit, and reduce noise and distortion as much as possible. Therefore, I have replaced different varieties of coupling capacitors multiple times when making and Tian Mao route. In the past, I used it to prepress the platen to weld the machine. Attempts to use the circuit board to make this premium, I have experienced the production line board when I make the decoder, first use the Protel system The probably trend of the loop board, combined with your own experience, I think it is good to design and reuse the line simulation to test its performance. After making a few circuit boards, it will receive a relatively satisfactory result. The current level of the ground is a little ground. Everyone can see that the fixed 锣 in the board is the grounding point of this pre-stage, and the wire line is relatively smooth, from the signal input to the signal line at the selection switch. Using the Kimber Small Signal Line. Since there is no Kimber small signal line in the region, when I go to Guangzhou to obtain MSCE certification, I bought some in Guangzhou. I have always like to use pure copper wire. Who knows that it is not enough (Kimber small signal line very expensive), I have to make a compromise in the beautiful view. This can be seen from the signal line in the figure.
Be
I often hear some people say "Audio is simple is good", but Krell's boss Damel d'Agostino said: "Simple representation is easy to do, not necessarily good." In fact, which Hi-End product is simple What is it? The pre-level is very sensitive to the AC noise, to reduce AC noise and thermal noise must use a pure power. So I started from the power supply, this machine used high pressure regulatory and filament DC voltage regulatory. Many of the high-voltage parts have advocated dual power, but when I actually use it, it is difficult to do two channels of components that include transformers and electronic parts, which affects the appearance and space sensation of sound. . I have an experience before imitation Matisse. The last production is in the power supply for a few days in the power supply for a few days in the power supply. It is also used to use the aspirated Acrosound, the as-producing transformer (second-hand). Please see "Imitation Matisse sequel" for details. And for the DC power supply, the presentation is different, and I have no preference. But in my preampli, especially when using high-magnification pre-magnitude, I still insist on using DC voltage regulating. I think the tone can be adjusted by other contracted parts, but there is an exchange sound that I can't tolerate. The signal-to-noise ratio is the most basic indicator of the premium, and a good sound is much better, as long as there is a little exchange, it will be unbearable. The high voltage of this unit passes through four high-speed Philips rectifiers to two golden ROE 400V220U capacitors, after filtering, after a 4.7K resistor enters the lower filter capacitor RoE 400V220U to a precision low ripple regulator, After the high pressure after regulating, it supplies a second level of a total of 6dJ8 composed of SRPP level and 6dj8 composed of 6dJ8 after passing by the high pressure. Another group of high pressure passed through a 100K buck resistor after a 100k buck resistor and a voltage regulator of the first stage signal input stage of the first stage signal input stage after a 100K buck resistor, to ensure that the voltage fluctuation is 6dJ8 Can set up reliable work. Only such production can be exchanged for abnormal communication noise. The filament portion first passes through the bridge rectification, use the ROE 25V3300U to filter the LM317K regulator integrated block regulation. It can be seen from the figure that there is a radiator on the LM317K. I used the transformer that I used the method and winding in the "Burning Transformer Wind Method" and "Impact of the Transformer on the Physicius" articles to wind the transformer and used high silicon steel to do transformers, so the effect is good and my HP antique The sound of the stage transformer is not divided into it. Here I feel that every a machine is a little gain, which has a great advantage to growing your own fever. After welding the machine, I listened to the feeling of feeling a little hard and a bit of sand, not very smooth. But I know that this is a new machine, as long as the machine will have a lot of time. The previously-level noise is extremely small, and when the volume potentiometer is maximized, there is no noise in the hound (say no noise is exaggerated, only some of the thermal noise), use the signal generator as a source input The preamplifier is to the maximum of the oscilloscope when you screw the volume potentiometer, and there is no clipping distortion, which shows the greatness of the design of Tian Mao's line. However, because of its later generations, the golden age of the tube has emerged, and it is known as "life is not in the case." For sound, I think it is more comprehensive, and the gallbladder is not sweet, the analytical force is excellent. After listening to a few days, I came to Tuner as a machine, I think the signal source of Tuner is a good signal, and there is a signal 24 hours a day without singing the CD player. The first choice for a veritable cradle machine. What I want to say here is that the choice of gallbladder on this machine must pay attention to the gallbladder of my test stage is a domestic 6n11. After the SIEMENS's gold foot E88cc, I'm a big change. In Spar 110, it is more obvious, don't know what solution? Domestic 6N11 is far from the dynamic analytics and imports of imports. The challenge in this machine is most obvious that the golden foot 6922 bile with amperex (also known as the blow), its photo is shown below. This gallbladder is rare in the market, and Siemens's gold foot ECC88 is more common. I am also the first time I bought this gallbladder, not much eight. Just didn't think that this kind of voice is so sounded. I really don't want to go to Guangzhou. Everyone can use all kinds of courage to make a different kind of courage to achieve the ideal place in his mind.
Since this machine is made of a circuit board, it can be sound as long as the position of the relocation is placed. So simply easy to do, as long as the potentials are normal, and there is no great mistake in the device (such as the position of the relocation of the relief or the inversion of the capacitor positive and negative). Because it is a circuit board, the enthusiast can be made by the line of Figure 1 or Figure 2, where there is a high line dynamic and analytical force using 6dj8. It is more sweet with the original line, but the dynamic and analytical power is less than 6DJ8 lines, you can make it according to your own requirements.
Our other product:
