6P14 low-power tube amp, 6P14 power amplifier
Keywords: tubes, amplifiers, 6P14
Class A amplifiers more and more people's attention. The reason First Class A amplifier odd harmonic crossover distortion, no harsh does not exist, which is the key to the pure sound quality. The second is a Class A amplifier has been working in the best condition, it does not occur as the switch B amplified distortion. It is characterized by large negative feedback loop can be canceled, thus avoiding transient intermodulation distortion, greatly improving the dynamic index. This machine is designed for the study design, not for fair without the sound just excellent. CPI tube using single-tube amplifier, both for reasons of quality, but also taking into account the production of push-pull amplifier tube amateur pairing difficult to solve the problem. Although the lower tube Pure Class amplifier efficiency, but its power reserve compared with the transistor amplifier can be as small as half or less. Research data show that there is pure Class A and Class B Power To get the same quality (refer to Pure Class A amplifier power does not exceed the rated value), the latter shall have nine times the former power reserve. Therefore, the absolute efficiency Pure Class A amplifier could be worse, but the efficiency is relatively little difference. Tube sound gentle with one of the Confucian style, is the so-called moderation, coupled with the tube itself unique classical and nostalgic mood, atmosphere enough to bring lots of warmth to the study. If those Ming gall KT88, KT100,845, etc., may be referred to as ru, then the machine can be called a small Confucianism, if invited into such a small Confucianism in your study, you are equal to procure a bosom friend, when he would softly melancholic paragraph language to comfort you, when he was laughing happy to add to the fun, why not this machine has the following characteristics?:
No loss output power 2 ~ 5W;
Circuit is simple, no special element, and gives some experience Replacement element;
The machine wide frequency response, low distortion, low tone control circuit is provided with circuitry, and easy to use.
Principle circuit diagram of the whole circuit shown in Figure 1. Two pipes are required for each channel. Amplification of the pitch boundary is divided into two parts for the network before and after. Voltage amplification section front part, rear part of the front end stage and amplifier stages. VE1, VE2 selection of high μ tubes 6N2, to improve the sensitivity of the machine. Voltage amplification stage main technical indexes is the magnification of the frequency and degree of distortion. 6N2 amplification factor of 97.5, sufficient to meet the requirements of the machine. Using sealing coupling, the magnification of the intermediate frequency region is large, the amplitude frequency characteristics, and the phase frequency characteristics are flat. While the low frequency region and high frequency region are lowered to certain rules. Usually increase the upper limit frequency to reduce the R4 value, to extend the lower limit frequency to increase the C1 value. After repeated debugging, the electrical voltage amplifier screen is 150K, and C1 is 0.1 μF. The front end stage is typically a cathode having a bias voltage and resistance autogenous leapfrog negative feedback voltage amplifier.
Amplifier stage selection of low frequency power amplifier pentode 6P14, the possession "Shu quality excellence" reputation in the audio industry, its large cathode area, long life, high transconductance particular soil 1.3mA / V, and the sensitivity of amplifier efficiency are high, is an excellent amplifier tube, the actual installed capacity audition also confirmed this. VE3 the gate resistor R11 has some influence on the sound quality, to obtain a better frequency response, the unit value is smaller 400kΩ. The main advantage of the diodes five amplification factor is larger, as an amplifier, a higher magnification. At the same time, due to the double shield of the curtain gate and inhibits the gate, its crossover capacitor is small, such as 6p14 less than 0.2 pF, high frequency loss is small. Of course, compared with the transistor, five o'clock diode as an amplifier, distortion and noise to be larger. However, after the unit inside the system sounds pure and natural sound, transparent and bright, the noise did not recognize, which is related to the CPI working condition. 5Z2P power rectifying part is then subjected to π type LC filter circuit of the power supply unit. Wherein the filament winding, the voltage amplification stage and the amplifier stage should be independently wound, in order to reduce the mutual interference.
Specific experience 1. Components chosen. Tube VE1, VE2 selected "J" grade 6N2, 6N1 available direct substitution. VE3 selection of Beijing brand 6P14, with the same pipe model 6BQ5. This machine does not have special requirements for resistance and capacitance quality, and the resistance can be used for ordinary carbon film resistance. I used the resistance are all old tube radio demolition supplies. It is only for circuit operation, and the power of the resistance is preferably selected, and the author uses the specifications of 1 watt power. Capacitors C1, C4, C5, C6, C7 can be an ordinary polypropylene capacitors, the voltage can be 400 or more. C2, C8 ordinary high-voltage solution, the pressure can be greater than 350V. C9, C10 pressure should be greater than 400V, with priority conditions should TV electrolysis. C3 use 200pF Mica. The power transformer power should be greater than 100W, the primary and secondary subtarties should be added with the shield, and each group filament is independently winded, and the strip is shown in Figure 1. The power transformer core model uses "GEIB-35" with a cross-sectional area greater than 35 × 47mm2.5Z2P supply voltage of 5V, and the φ1.21mm enameled wire wound around 24 turns, the current should ≥ 3a. The filament power supply voltage of the power unit 6P14 is 6.3V, with a φ1.21mm enameled wire by 30 turns, tap at the center, that is, the tap E, the 6P14 cathode can improve the signal-to-noise ratio. FIG choke L CEIB-22 available silicon steel sheet, stack thickness 22mm, with about 2700 turns of enameled wire Φ0.28mm. In order to produce a DC choke is not saturated on the core due to voids increase the reluctance. To this end, the iron core can be laminated with a stack, a void of about 0.5 mm, and the insulating paper is plugged, and the winding can pass 150 mA current. Sound level of the output transformer will impact the quality, can be purchased finished audio output transformer, power is 5W, the primary impedance of 5 ~ 5.2kΩ, secondary output impedance 4 ~ 16Ω, model "OPT-5-5". It should be used 470kΩ potentiometer RP1 double exponential acoustic dedicated potentiometer. RP2, RP3 can be used in the above general power 2W potentiometer. RP4 with about 2W 100Ω wire potentiometer. 2. Installation and commissioning. Readers may be selected according to their installation conditions. I use a tube radio base using its original seat tube, transformer and terminal, install very convenient. If the reader can use a printed circuit board, the reader can also use the printed circuit board to install the power transformer, the electric transformer, the tube and the large electrolytic capacitor are mounted on the metal sheet base, and the printed circuit board is mounted to the base, which can prevent the relocation element due to temperature changes caused by reference. In order to prevent interference signals entering, shall take the necessary measures. Power transformer can be mounted upright, from branched stent, so that some distance above the base, can be prevented from entering the magnetic circuit of the transformer leakage caused by hum floor. Power transformers and choke line package line package mutually perpendicular, and as far as possible away from the output transformer. VE1, VE2 from power transformers. Electrolytic capacitors away from power amplifier, in order to avoid overheating and dry roasted failure. The wiring of various parts should be as short as possible, the traces cannot be chaotic, the same level component should be close to the tube of the tube, and ensure a little grounding. Valve gate wiring as short as possible and avoid the screen parallel to the electrode lead. Screen electrode wiring circuits and the gate circuits, and slightly away from the bottom plate that thus reducing the number of potential distribution capacity. The best filament wire twisted together to go on the floor, in order to reduce hum caused due to the filament. Bypass capacitor must be connected directly to the stem or bypass this point level ground. The wiring head of the capacitor cannot be too long because the electrocharged electricity of the bypass is easy and other line inductance, and the long wire itself has an inductance, and the high-frequency current forms an induction, which reduces the role of the bypass. Special attention should be VE1 metal gate lead shielded wire, and in that close to the gate, grounding the shield. As long as the matter can be noted above, careful welding, installed after the system is correct, you can power burn audition without making adjustments.
Replacement experience partial element wherein the voltage amplification tube can be used instead of 6N1, R4 instead of the reduced 100kΩ, R8 reduced 100kΩ, R10 to around 50kΩ. Changes with time instead of the above method 6N15. Electronic power rectifier diode 6Z4 available substitution. Single tube 6Z4 because the maximum DC output current of only 75mA, so the application of the two tubes used in the parallel circuit 2 changes as shown in FIG.
Substitution may also be a semiconductor diode. Only a slight change in sound quality, modifications circuit shown in Figure 3.
Type low-frequency speaker unit may YDS-2004 8 inch rubber speaker edge, with the high frequency unit YDG-3 type 2.5 inches small tweeters, by simple capacitive divider, the selected crossover 3kHz, the acoustic capacitance is dedicated non-polarized capacitor, type such as CD94, CD95 type, can also be two good quality electrolytic capacitor (20μF and 10uF) Replacement inverter series, but the effect is slightly worse. Error-free as long as the element, correct weld, burn boot Trial half hour, if the circuit is stable, the feedback resistor R13 to cancel the test, the sound quality is more translucent at this time. I had friction with Philips CD47l type CD player for audio, direct refutation of this machine, push closed bookshelf speaker made two speakers described earlier, in the study listening, lingering aftertaste. Listen dish first set aside in 1990 by the German wind Granma published by "Peter and the Wolf," No. "DG429 396-2", Abbado by the Chamber Orchestra of Europe playing history. An opening will be attracted to the person in the story. Small speakers of the unique sound of a clear sense of immersive Young, close your eyes and they feel that they are involved in the deal Peter and the Wolf. Set aside as the real history of nature, closely linked to the plot. Peter distress tense atmosphere was dignified people breathe mining, when the wolf is defeated fighting enthusiastic lively rhythm encouraging, people can enjoy the music of infinite charm of this art. But also with Jennifer Warner's "Lan Yu floor," Listen, this machine an excellent interpretation of the human voice so charming voice with the magnetic Jennifer Warner is reflected extremely perfect, saxophonist Paul Ostrofsky Martha Sa The roning dance makes you like. People praise Tiandie pure matter of tone, but also very tan Castle electricity to the tube is not old. It has also added to the front straight split machine, listen to folk music with homemade DM62 head deck. During a zither music {Mountain and Flowing Water "empty mood far, vulgarity, could not help but Evans Quan.
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