Author: Zhong Wenxiang
At present, computer sound card audio, MP3, MP4, and CD, SACD, DVD, and even blue-ray discs are mostly unzipped number of model swivel flows, usually with transistors or integrated circuit audio amplifiers, although there is a certain advantage, but The sound quality is slightly straight and hard, mispolated, there is less prevailing, ie, is usually called digital. The audio amplifier made by bile duct (tube), playing multimedia audio sources, can effectively improve sound quality, can achieve good hearing, effectively overcome multimedia audio-tone cold plate hard, lack of panicism, make people's music music, I don't heal! In order to solve this problem, make the post-level playback music more voices, more sound, in recent years, popular bile duct (tubes) audio amplifiers, play computer and other digital sound sources to get good listening, Effectively overcomes the hard-up of digital sound tone, so that the music is full of vitality, I will not heal! Due to the use of bile duct, the frontier of the pulse signal waveform based on digital-to-analog conversion audio has a time-delay effect, greatly Improve the sound effect. The biliary audio amplifier has a unique expression of the audio signal. Some LP black glued enthusiasts are also in the case of ambiguous, and believe that the as the courage is the perfect match of the LP player. Single-ended inquiry sounds, very fascinating, especially in expressing musicians, and unique charm. In order to further improve the performance of the single-ended, enhance the performance of the music, make the sound quality better, more perfect! Trial, one 6C16 inductive direct coupling FU50 single-ended machine, insist on the concise first in the premise of the principle of the circuit Principle, more components, more distortions, can minimize components. The amplifier power release is extremely high after successful production, and if you are interested, you may wish to try it. As shown in the figure, the voltage amplification is carried out by a high-binding low noise wideband single tripode 6C16, and the inductive direct coupling between 6C16 and FU 50 is ensured that good amplitude frequency characteristics can also appreciate the charm of electromagnetic coupling. Direct coupling inductively coupled, inductor capacitive coupling, and transformer coupling in performance, and effectively overcome digital sounds, enhanced music. In order to improve linear reduction, FU50 uses a triode connection. 6C16 high cross-conversion medium-screen transconductive, plus sensitive load, can output 80V to the voltage of 80V, which is enough to promote FU50, this tube is used for voltage amplification linearity, tone, emotion, color, plus single The pipe package, the sound bottom is clean, the sound area is accurate, and the sound is analyzed. It will be noted that the motor voltage amplifier 6C16 operates in a small signal input pre-stage voltage amplification, and does not use the cathode current negative feedback, that is, the 6C16 cathode capacitance is not less. Although the cathode current negative feedback can change the sound quality, the balance gain, but still a dissection, the weakness of the audio signal is lost, dynamic compression, unclear, the sound is straightforward, the music is missing, the cathode The greater the resistance, the more obvious. 6C16 inputs the front stage voltage amplification stage as a small signal, if it is not good to transmit and enlarge the audio signal, the good FU50 level is no good, so the 6C16 does not add cathode current negative feedback. In order to stabilize and balance gain, a small amount of current negative feedback is added in the FU50 cathode, since the post-grade FU50 operates in power amplification state, the impact of the cathode and the frequency pull is already small.
Components Select this unit to use Beijing Brand 6C16 and FU50, and the panel is related to the form. Tonguang 523Pa, filter capacitor, British TCC high-pressure oil dip, 6C16 cathode capacitor, Philips electrolytic capacitor, Fu50 cathode capacitor, 6C16 catholytic electric resistance, domestic 2W green carbon film resistance, FU50 cathode resistance Porcelain resistance. Volume potentiometer uses a steward potentiometer. The coupling inductance self-made uses the EI type high-quality core, the cross-sectional area is 26mm × 45mm or more, such as Z11, H1O, etc., 3800T, core magnetic gap liner with line 0.16mm, etc. 0.05 mm sheet of paper, the inductor is about 60 hours (20 Hz / -1dB). Output transformers 3.5k30A product, core cross-sectional area of 38mm × 52mm, frequency response is 20 Hz ~ 50kHz / -2dB, high high school low frequency three ends performance, sound quality is satisfactory, cost-effective. Homemade can refer to the relevant information. The choke is used in 27 products, and the power transformer power is greater than 250W.
Harmonic qualification due to the polar capacitance of the bile duct, easy to constitute a resonance with other components, more excitation high-end harmonics, where the harmonic listening is sweet, very resistant, in order to retain even harmonics, the whole machine is not allowed Use bile duct, blocking parts and wires in parallel. The wonderful harmonics were weakened by appropriate current negative feedback through the FU50 cathode. With regard to the unfavorable tone of the even parallel element, this view is in theory to further demonstrate, but in practice, in the past period, the popular two tubes are connected in parallel output. It is better to listen to the single-tube single-ended output sound. At the end of Yunnan, Guangzhou and other places, the single-ended award is still a single-tube or three tube parallel single-ended machine. From the single-screen dual screen, the dual-screen pipe is not as good as the single screen tube sound, and the courage is always selected by the RCA2A3 straight heat triode, and the single screen RCA2A3 is always selected, and the dual-screen RCA2A3 is not used. The reason is that the single screen RCA2A3 Making single-ended tone is better than selecting dual screen RCA2A3. Welding machine debugging the unit used by the unit to be carefully tested, and after confirming the pass, the welding can be etched. After verifying that the welding is correct, it can make a test machine and adjust the work point. Since the 6C16 is directly coupled to the FU50 two-stage straight coupling, the DC operation is adjusted to each other, so it is first estimated that the partial voltage resistance value is the cathode resistance resistance value of each tube according to the pipe operating point, and then temporarily replaces each resistor adjusted by the electrical resistance. The working points of the tube, since the working current is not large, first adjust the two cathode resistances of the FU50, so that the FU50 gate is biased to 50V (cathode to the gate), the screen is 60mA, and then adjusts 6C16 cathode resistance, so that The cathode voltage is 1.5V, the screen is 10mA, and then repeats the above process, preventing the mutual involving the work point, the mutual machine is a week, the job is repeated, and the day is not correct, if it is incorrect, Adjusting, if necessary, replace the relevant metabits until it meets the requirements. If there is no change, the resistor is replaced with the above-mentioned resistance, and then the machine is made, and the perfect sound is perfect. Online audition This machine is considered to be refined and improved for previously soldered single-ended machines. The next task is the audition and mock. Put this unit access system, the source is the Philips DVD, the homemade 6J7 fare-level, the speaker is the self-made eight-way junior frequency speaker, the disc is a more classic audio disc "Fruit Sweeping Disc 8", "Autumn Rose "and full-frequency disc and pop. The audio has focused on the "four seasons", the "four seasons" of Tao Yuxi, the "Opportunity", the "Opportunity", the bass "Yellow First Drum", boot, the sound is magnetic, the people's voice is beautiful, high and medium low frequency performance Full, the sound area is accurate, the sound is transacted, the music is full of music, the movement of the characteristics, depicts the sound of the natural life harmony, gentle and sweet, very charm.
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