Talking about how to increase the signal-to-noise ratio of tube amplifier
I do n’t know if audiophiles have noticed that most of the world ’s high-priced audio equipment claims to use scaffolding welding technology, especially high-priced amplifiers, and almost all use this time-consuming and labor-intensive method, and give up Universally used printed circuit boards. The advantage of this is mainly to further improve the sound quality of the playback and make the wiring between the circuits more reasonable. Practice has proved that scaffolding welding is indeed more excellent in sound expression. Therefore, it is also an experimental object of amateur enthusiasts making hands-on school. Traditional printed circuit board welding is the mainstream in the electronics field due to its compact structure, beautiful appearance, relatively small size, and ease of mechanical welding. However, since the printed circuit board uses a copper layer coated on the insulating board as a conductive object, the quality of the copper layer oxidation, N factor and its thickness have certain limits. For the sake of neatness, most manufacturers use computer The design and drawing of the board, their copper skin conduction paths and corners are all sharp, and the thickness cannot be absolutely consistent. The current is not smooth when flowing through these places, and the resistance of the circuit board itself cannot be selected randomly like a scaffold. The capacitance component between adjacent copper foils cannot be made very low.
Taking a tube amplifier as an example, it is easy to produce sparking discharge on the circuit board at the sharp corners and the copper foil near the high voltage. Due to the high internal resistance of the tube amplifier and the power supply voltage, the circuit board between the copper foil Partial capacitance will also affect it, and damage the transparency of sound reproduction and other indicators. In the design and manufacture of amplifiers, in order to reduce interference and improve the signal-to-noise ratio, the gate drain resistance of the gate is required to be connected to the input gate in the most recent way, preferably soldered directly to the gate pin, and the cathode The resistance is also required and preferably grounded at the same point as the gate-drain resistance, which also reduces the potential difference between them, which is difficult to achieve on the printed circuit board, and the use of ceiling welding can be easily achieved.
In fact, not only the amplifier, but also the crystal machine has some disadvantages other than the above, and even has a great influence on the crossover in the speaker box and the connecting line between the speakers.
Nowadays, the crossovers of most speakers are made with printed circuit boards. Although they are neat and beautiful, the influence of conductive copper foil also exists because the crossovers of speakers often pass large audio currents. The cross-sectional area of ​​the copper foil of the board cannot be made too large, so that part of the power will be lost, even if you increase the cross-sectional area to a certain extent, but the quality of the copper foil has not been heard of 6N to N High purity, for the current fever concept, more or less will leave a little regret in the hearts of enthusiasts. ………
The so-called scaffolding method is to directly jumper weld at each connection location with wires of different quality thickness, or directly twisted and welded by the lead of the component, thick wire for large current, thin wire for small current, due to the inter-wire There is insulation layer spacing, which naturally will not form a short circuit, but the technology of scaffolding is relatively difficult. Pay attention to the direction between the wires, avoid the parallel arrangement that can cause coupling interference, and arrange the ground point of the whole machine reasonably. The layout is arranged, the more intuitive and simple the shorter the better the effect, the reasonable design can reduce the resistance of the circuit to the minimum, so that the flow of current is more smooth and unimpeded, the distributed capacitance can also be done very low in the ceiling welding, so that the mutual Interference is further reduced, improving the quality of playback.
The high-tech scaffolding welding is a beautiful lamp AC tube radio. Almost without exception, the scaffolding welding technology is used to make it. The crystal radios and tape recorders that are now popular are also unmatched in terms of sound quality and timbre.
Because the production of scaffolding welding depends on manual and superb technology, their manufacturing speed is many times slower than that of printed circuit boards, and the cost and price increase will follow, which is also expected. Among the results.
brightness
LCD is a substance between solid and liquid. It can't emit light by itself, so it needs additional light source. Therefore, the number of lamps is related to the brightness of the Liquid Crystal Display. The earliest liquid crystal displays had only two upper and lower tubes, the lowest of the popular type was four lamps, and the high-end one was six lamps. The four-lamp design is divided into three types of placement: one is that there is a lamp on each of the four sides, but the disadvantage is that there will be dark shadows in the middle. The solution is to arrange the four lamps from top to bottom. The last one is the "U"-shaped placement form, which is actually two lamp tubes produced by two lamps in disguise. The six-lamp design actually uses three lamps. The manufacturer bends all three lamps into a "U" shape, and then places them in parallel to achieve the effect of six lamps.
Tip: Brightness is also a more important indicator. The brighter the LCD, the brighter the LCD, it will stand out from a row of LCD walls. The highlight technology we often see in CRT (ViewSonic is called highlight, Philips is called display Bright, BenQ is called Rui Cai) is to increase the current of the shadow mask tube to bombard the phosphor to produce a brighter effect. Such a technology is generally traded at the expense of image quality and the life of the display. All use this The products of this kind of technology are all bright in the default state, you always have to press a button to implement, press 3X bright to play the game; press again to turn to 5X bright to watch the video disc, a closer look is blurred, you need to watch The text has to be honestly returned to the normal text mode. This design actually prevents you from frequently highlighting. The principle of LCD display brightness is different from that of CRT. They are realized by the brightness of the backlight tube behind the panel. Therefore, the lamp has to be designed more so that the light will be uniform. In the early days when selling LCDs, it was a great thing to tell others that there were three LCDs. But at that time, Chi Mei CRV came up with a six-lamp technology. In fact, the three tubes were bent into a "U" shape. The so-called six; such a six-lamp design, plus the strong luminescence of the lamp itself, the panel is very bright, such a representative work is represented by VA712 in ViewSonic; but all bright panels will have a fatal injury , The screen will leak light, this term is rarely mentioned by ordinary people, the editor personally thinks it is very important, light leakage means that under a completely black screen, the liquid crystal is not black, but whitish and gray. Therefore, a good LCD should not emphasize brightness blindly, but more emphasis on contrast. ViewSonic's VP and VG series are products that do not emphasize brightness but contrast!
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