Keywords: small cheap electronic pipe power is designed
Self-designed small and cheap electronic management power (as ambigram), the author believes that the following questions should be considered. First, what problems are there there in the market sales in the market. We can design whether the small and courage can solve these problems. Second, spend less money, can you get a good sound quality? First, let's take a look at the market selling. At present, the market sells in the market has the following designs: 1. Place the line with the direct heat pipe as the output tube. The output tube is a straight-heat triode, and more than the seller has been promoted as "gallbladder", claiming that its sound quality is like "sound of the sound". The author has passed some kinds of biliary stores, listening to the amplifier made of output controls such as 2A3, 300B, but always believes that its cost is still high, cost is still high. First, the straight-heat tripod tube is designed early in the last century, the general internal resistance is low, the magnification is low; if the equivalent output power is equal to other output tubes, it will inevitably be highly demanding. Therefore, the voltage amplifies is usually 2 levels. From the perspective of signal amplification, the higher the voltage amplitude required, and the distortion of the voltage promotion stage should also be large. Second, use a straight-heat output tube, in the absence of power supply, no matter how the cathode is used, the exchange sound cannot be completely suppressed. If the high sensitivity speaker is used, the background of the approach 3 millivolts will make the speaker in the music static, and the annoying communication sound can be heard. Some manufacturers, in order to inhibit the exchange of exchanges, use DC to supply power to the output tube cathode, but due to the presence of a DC pressure difference between the cathode, there is a difference in the density of the cathode emission electron flow, thereby affecting the life of the output tube. Therefore, the author does not think that the direct-heated output tube is the best solution. 2. Under the beside hot cathode quick-shooting quadrupole or five-pole as the amplifier of the output tube. More low output tubes are 6P3 (6L6), the screen pressure is usually 360V, the push-pull output effective power is about 25W, and the armed output is about 6.5W. If the screen is pressed, the output is up to 10W. The kt66 of the mid-range price is 390V, and the push-pull output effective power is about 30W, and the armed output is about 10W. The five-pole output tube EL34 (6ac7), the screen pressure is usually 370V, which is a push-pull output effective power about 48W, and the A-armed output is about 10W. Others is a small-scale courage from the low-priced quadrupole 6p6 or five-pole 6p14 as the output tube. The push-pull circuit output is about 10W, and the single arm is about 4W. This kind of aspiration, with the speed of the quadrupole, the sound is owed, and the diode is output to the output tube, the bass circles are in a little lack. 3. Power amplifier combined with gallstones. Bold bile, the market is usually the frontal stone circuit. That is, the input is enlarged by small double triaces, and the end-class is an integrated circuit, or the field effect tube is output. From the lithographic tone, the bass is powerful, but the midrange and treble lose the charm unique charm. And the price of the price is higher than the incense. In summary, our kinds of courage should reach the following non-instrument listening standards. 1. In any case, there should be a background communication; no noise in front. Turn the amplifier to the sensitivity speaker, open to the maximum volume, put the ear on the speaker, can't see the exchange and background noise. 2. The bass part, should be strong, the damping is appropriate, slightly smoother, but does not affect the clarity; the middle sound should sound colorful, especially listening to girls singing, there should be sweet sense; the treble part should be slightly transparent, must eliminate the treble The part issued "" noise. 3. Open to the maximum volume and cannot have a sense of disturbness. To meet the above requirements, what questions should you pay attention to when designing it? First, put an end to exchange sounds 1. Chassis version - amateur production, usually use iron bottom plates. The author believes that this is the least outless. The reason is that iron is easy to magnetically magnetically magnetically, and the leakage of the power transformer can be easily transmitted to the output transformer, causing a convergence of more than 2 millivolts. And this communication sound cannot be overcome. Unplug the output tube, the speaker is like a small communication. Some people think that the shields of the transformers can add such exchanges, in fact, due to the mounting of the transformer on the bottom of the iron, there will be an alternating magnetic field through the iron bottom. Therefore, the best solution is not to use ordinary black and white iron as a iron. The bottom of the shopping chassis, mostly stainless steel production. Stainless steel magnetic performance is much lower than the iron, it is better choice; but the price of the purchase or customization is high. The aluminum plate does not magnetize and has an electric field shielding effect, and is a good material that prevents the sensing exchange. The disadvantage is that it cannot be welded, and the ground pile can only be connected to the copper screw and the wiring flakes. A printed circuit board for double-sided copper has a printed circuit board, making a small bottom version, and is also a good material, and it is easy to process. If the asked, there is a homemade shell package, the author thinks that the old aluminum lunch box is spliced, and it is also very good. In summary, it is necessary to use a material with low magnetically low and a material with electric shielding, which can effectively prevent the interference of the power transformer to output transformers. 2. Design of preamp and excitation - from the author's experimental results, 6N2, 6N9, the cathode is the strongest induced from the filament, and the insulation between the cathode and the filament is relatively thin, and it is easy to leak. Therefore, some kinds of aspects are typically used for preamplifiers, or power supply, or DC power supply to thoroughly solve the preamplist. The author believes that this will bring trouble to power. Some circuits use filaments, with positively charged with the output tube cathode to prevent the wire emission electrons from being exchanged by cathode absorption, which is more effective for the excitation level and the output stage, which is limited to the pre-magnification. The level input impedance is high, the resistance value of the volume potentiometer is also high (usually 100K-500K), although shielded lines or other shielded measures, weak alternating electric fields (from filament or power transformers), or will still make Enter the tube gate induction weak AC signal, if the volume is enlarged, the more obvious communication. We hope that the input is no communication when there is no signal and no sound source device (DVD \ VCD \ Sound \ Sound Card). This requires us to resolve the process, material on the board. From the collection tube, the author believes that the 6N3 or 6N11 pre-level is best enlarged. This is because the 6n3 and 6n11 originally designed in the high frequency circuit, and the gate input of the DC series is used, the screen is output to the gate ground output circuit of the cathode, and the filament and the cathode are insulated, and the filament is lowered. Induction between the cathode; the second is that the 6N3 and 6 N11 high tone characteristics are good, which is conducive to the pass bandwidth. Using 6N3 and 6N11, the previous stage is enlarged, and it is possible to better reduce the sound of induction exchange. If the filament DC is powered, the sensing exchange can be completely avoided. The above is said to strictly requested full of enthusiasts. If we change your idea, what is the transistor in the predecessor (first electric pressure amplifier)? Take experiment, this is a better solution. The crystal high-frequency tube is advantageous to expand the passband width, and the second is not a filament, the size is small, so it is possible to completely eliminate the sound. Second, the power output and the speaker power output is a headache. This is because of the promotion, which biliary tubes will be said to God. In fact, take a closer look at the characteristics of the bile duct, and we can roughly see that when the push-pull output, the straight-heat pipe (triode) is generally about 3% when it is not negative, and its distortion is generally. 1882.5%. 1882.5% . Speed tetles or five-poles, push-pull distortion is usually 3% -5% when no loss is incurred, and the single arm distortion is nearly 10%. From these data, the biliary tube is not so much different from the general bile duct. From the perspective of subjective listening, the high-heat triode needs to be pushed high, so the effect is not very ideal in small volume; and there is background communication. Some people write, there is no gallbladder without such exchange. The author does not feel the same. The use of speed tetles and five todes in playback, there is a difference. Therefore, the author believes that it is better to use the electronic frequency division mode. That is, the push-pull method of the speed tube is used as a low cannon; the left and right channel output is used by the five-pole arms. If the subwoofer has the effective power of 20W, the valid power of the left and right channels is about 10W, then there will be no problem in using a modern speaker. If you change a thinking, use a high-sensitivity old-fashioned speaker (low-spoiler with pure paper pots - such as Feile paper pot 10 inch, bass; Feile Elliptical 4 × 6 inches - middle sound, horn 4 inch tall ", its effect is released It is more beautiful than the current low-damped PC basin speakers on the current low damping PC basin. Then, the power amplifier does not require that power, the bass 10W is enough, the medium and duty. 1882.3W can meet. In terms of speaker design, if the volume is sufficient, it can also be used in a back-opening, so that the play is more natural. See next page for more. . . . Next page
Our other product:
