Use high μ tube as a gallbladder amplifier ----- Tube preamp

Use high μ tube as a gallbladder amplifier Author: Dai Hongzhi Today, some discs are made in HDCD format, larger than ordinary discs, rich in detail, clear level, wide sound field, and a fresh place. How to make your own existing playback system restore music? The daring front-level amplifier made by high μ triode can be achieved. The line is shown in the figure below, the input stage voltage amplification is a common cathode amplifying circuit with high μ double triode 6N9P (foreign model 6SL7). Due to the high voltage gain, the cathode resistance does not have a bypass capacitor, and VE1 has the current level of current negative feedback. , Make the distortion reduction. 6N9P = 70, it is characterized by clear, gorgeous, beautiful, the sound area is wide, dynamic, and the performance is better when the power supply voltage is higher. Foreign cranes often use this cougar input grade small signal amplification. V is also a cathode output, which uses a medium μ dual triode 6N8P. Although there is no voltage gain, the input stage gain has a large margin, and the unit still has an energetic energy incentive post-level amplifier. V is also separated as a buffer level, while the output impedance is lowered, making the pre-stage and post-level amplifier. The unit is equipped with a large loop negative feedback, and the feedback voltage is introduced from the output of VE2 to VE1 to VE1, and the feedback amount is about 4 dB to 6 dB. There are two kinds of feedback voltage leadback of the large rings, and the output capacitance of the following figure is only one, the feedback voltage is introduced by C2, and this connection is only the tone and frequencies of the amplifier, and the calibration is easier. Another method is shown in the figure above. The feedback voltage is drawn from C1, C2, and C1 has a large impact on the sound, frequency sound, etc. of the amplifier. When the campus, C1, C2 should be used, and C1 The capacity is less than the capacity of C2. The welding is completed, and the cathode voltage of VE1 has 1.5V to 1.8V, and the VE2 screen of VE2 is about 80V (no more than 100V). The cathode voltage is high from 3V to 4V, as a bias. When the cathode voltage is low, if appropriate to increase the resistance of the cathode resistance, the pressure drop will increase. After listening to the need to adjust the resistance of negative feedback resistor R8 according to its own needs, make the sound of the sound. This machine is suitable for transistor amplifier amplifier or 300B aspirated amplifier, if it is used in a good as ambiguous amplifier, the gallbladder is too strong. The improved method is to change VE2 by 6N6, as 6N6 tone comparison is neutral, at this time, the bass performance will be better. Therefore, in the case of the playback system of this machine before the installation, then determines that VE2 is 6N8P or 6N6.