6P14 small machine production, 6p14 Power amplifier
Keywords: 6P14 small machine production
6P14 small machine production
In recent years, there will be a sound card for the computer to increase the sound quality. Usually appreciate the volume of multimedia music in computers is not large, mainly for you to listen. Therefore, it is more appropriate to make a small power, such as using a big power, in the small volume, because the bile duct is not working in the best state, not only the play is not good, but also make the production cost and power consumption Increased, very bad. However, the small power is small in listening, the volume is small, the low frequency and strength of the music are still insufficient, so how to make the small power in the charm of high power, especially dynamics and strength. Aspects of the prevalence, etc., it is also dependent on treatment during the production.
According to this, the author tried to exchange a cathode compensation mirror drift such as 6P14 small bile machine, in order to appreciate the charm of the small volume in small volume.
Making small power incensery must determine the output power according to the actual listening requirements, and then determine the production scheme. It is used for multimedia play, this unit 6p14 is based on the triode connection, the maximum output power is about 2W, and the actual listening effect is very satisfactory. Since the small volume is low, the sound pressure is low, causing the human ear to feel unevenness in frequency characteristics, and there is a phenomenon in which high and low sound and insufficient overall strength. Since the volume potentiometer is large for the weak signal and high frequency components and music detail in the music component, in order to achieve both the purpose of controlling the volume, the sound is lively, and the weak signal and high frequency ingredients in the music component are not lost. Detail of music, this unit is equipped with an equal loudness compensation circuit on the volume potentiometer, when the potentiometer is placed in small volume, so that the hearing is still the same.
The first-grade of the machine uses a mixed bias voltage to stabilize the pre-predetermined operating point, the post-stage uses cathode differential compensation measures to improve the signal-to-noise ratio, reduce the thermal noise, and overcome the zero drift, so that the audio is concentrated, the sound field is stable, Replay music is sweet and sound.
The motor circuit is shown in the figure (the other channel is identical, omitted), the bile duct 6N3, 6p14 with better audio expression characteristics, the bile duct 6N3 high and low frequency extension, generous, very resistant. In order to improve the preamplifting stage 6N3 working stability, the bias is provided by the self-bias and fixed bias, that is, the mixed bias mode is provided, the self-bias current and the fixed bias current flow through the 6N3 cathode resistance to generate bias, both Half of sharing, which can effectively stabilize the work point of this level, overcome zero drift, and firmly lock the working state of this level.
The final power amplifier output tube is selected for 6P14. The tube sound is delicate and sweet, strong, high and medium low frequency characteristics, is a very excellent audio power amplifier tube, pick 6P14 into triode form, linear, sound color, single The maximum output power of the end is about 2W. The actual listening power is 0.3W ~ O. Between 5W, with 90dB of small full-range speakers, the sound is very charm, and the sound balance is full, listening to this power, no night is not affected by others. In order to sufficiently stabilize the working point of the 6P14, two 6P14 tubes constitute a differential cathode compensation circuit, and the zero drift caused by the temperature change, the power supply change, the forefront operating point, and the input large dynamic bass signal, and the input large dynamic bass signal. Overcome power ripples, improve signal-to-noise ratios, so that small volume listened to the bottom, and the music level is clear. Due to the large number of final currents, this measure has fundamentally overcomes the shortcomings of single-ended sounds, but the disadvantages of communication and noise, especially when the small volume is listening.
This machine output transformer impedance of 3.5kΩ / 8Ω, core cross-sectional area can be 26cmx45cm, silicon steel sheet is good, otherwise it is difficult to lead. The power transformer power is around 160VA. The whole machine work point debugging is relatively simple. Prior to energization, the output transformer is not available, which can be temporarily connected to a resistor load of about 10 Ω5W to protect the output transformer.
Workpoint adjustment: The power supply is 275V, by adjusting the 6P14 cathode resistance, the 6P14 gate is biased to -7.5V, and the two 6p14 screens are around 30 mA. The voltage amplifier 6N3 cathode voltage is adjusted to 2V (cathode current is 2 mA), and the fixed bias current is also adjusted to 2 mA. The cathode bias is generated by the self-bias current and the fixed bias current through the cathode resistance, and the two bear half . After the work point is adjusted, the 10Ω fake load resistance is changed to the speaker, can be listened to the machine.
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