Pre-amplifier made by tube 6p15
Author: Zhong Wenxiang
6P15 is mainly used in electronic pipe black and white TV video voltage amplifies, and the video voltage is widely raised, and the distortion size directly affects the quality of the TV image. The video amplifier is similar to the audio amplifier. But its requirements are relatively high. Drawing on video zoom ideas and trying to make audio amplifiers with video amplifiers, meaning unique.
6p15 is one of the professional tubes designed for high-frequency circuits, especially for the demand of the amplitude frequency characteristics FR and noise (noise), which is technically anti-micro-tiny effect, reflecting in the TV image to avoid vibration. Produce noise points, some "players" boldly "transplant" to the audio equipment. Actually produce unexpected advantages.
The pre-secondary circuit made by the author is shown in the drawings, which combines video amplifier circuit characteristics and fused with modern sound features. In the figure, the 6P15 cathode resistance is constructed in series, one resistor is connected in series, and a bypass electrolytic capacitor is connected.
It is pure direct and negative feedback offset. At 6P15 cathode one-end resistance is not connected to the capacitor, it is a negative, DC composite negative feedback offset. It can achieve both linear work points and ensure the stability of the circuit.
Considering the effect of electrolytic capacitance in high frequency in high frequency. At 6p15 cathode, a 0.0068μF mica capacitor is connected. To improve the transposition of the high frequency domain, the sense of air.
6P15 anode load resistance, reference to the frequency equalization circuit for classical singing machines. The series network resistor is connected in series from 1: 1O. In the 6P15 anode resistance, the "Frequency Correction" network is then connected, not only has a good improvement in low frequencies, but also inhibits high frequency noise, prevention of whisker, and eliminating self-excitement, so that the machine circuit amplifies linear balance, Frequently flat, small distortion.
6P15 output coupling capacitors should not be too large, the capacitance is too large and the volume is also large, which will increase the distribution capacitance; the value of the gate leakage resistance should not be too large, too large, will make the tube work unstable.
In this forehead, in order to obtain a pure DC power source, the dual power transformer is used in a non-system-coupled power transformer. The clutter signals in the grid are attenuated without being transmitted.
First, the component is selected by the power transformer and the blocking ring using Shanghai Radio 27y Product: The power transformer power is about 100W: the blocking ring specification is 10h / 100mA. Use the appropriate chassis. Plus the power transformer and the blocking ring. The components should be reasonably layout, and the welding should be as compact. The signal holder is made of gold-plated insulation.
Second, assembly debugging In order to exert 6P15 performance characteristics. Let 6P15 work in a typical working condition. By adjusting the 6P15 cathode resistance and the curtain voltage. The 6P15 cathode voltage is 3V, the cathode current is about 30mA; the cord gate voltage is about 150V. The unit 6p15 works around 30 mA, and the current is much larger than that of the general preamplifier. It is conducive to improving the texture of working stability and music.
Third, the mutter, the foreign player called Run IN, refers to the continuous use of the audio system for a long time, allowing the audio equipment to "old". Make the sound and smooth, smooth and smooth.
Fourth, online audition matching equipment: Philips DVD player, speaker is Italian proud card, speaker line is a US music ribbon Super F1a-tine Cab1e; signal line height (ORTOFON) AC-5000 8N oxygen-5000 8N oxygen-free copper wire, power cord For Hitachi 4N single crystal copper 3 × 3.5mm2 silicone rubber power cord; audio dedicated power purifier is G & WTW-05D.
When playing with genuine Hugo CD. The sound field is wide, very good, audio-visual positioning, good analytical force, low frequency, strong control, strong air, very pure sound quality. Let people feel unforgettable! Compared to several front levels of homemade. Feeling that its adaptation range is greater, the performance is stronger, and it is realistic to all kinds of instruments such as copper pipe music, symphony. Clean land, music is angry, this is all attributed to the video to enlarge the video management 6p15 disadvantages!
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