Started his tube amplifier the field of electronic enthusiasts, simple, good single-ended Class A circuit should be the first choice. Single-ended Class A tube amp has a mellow, sweet produce high success rate.
This article describes the line 6N1 constitutes the input stage. Standard connection to the power amplifier stage of 6P3P 6P3P for entry-level products, the quality is quite outstanding, low prices can production to minimize the risk, at the same time as long as the circuit design is reasonable, produced carefully, but also can play 6P3P fever realm. More importantly, I want to take this line, just like on the tube amp junior enthusiasts, by trying to gradually become familiar with the production tube amp.
First, the lines Introduction
An input voltage amplifier stage
6n1 one kind of well-respected circuit. The circuit has a small distortion, low noise, wide frequency response, is one of the outstanding line of tube amp circuits.
2 power output stage
Power tube 6P3P standard connection, the signal input from the control gate (⑤ feet), the screen grid (④ feet) and is directly connected to the power + B1. This connection is characterized by: high amplification efficiency. To achieve the specified output power amplifier tube in the characteristics table. The cathode resistor R6 to the output stage, output stage gate negative pressure to determine the in-14.5V. 6P3P anode voltage of 300V, vacuum gate-18.5v, screen flow is 60mA for Class A amplification, the output power of about 7.5W, basically meet the requirements of the general home environment playback.
3 power circuit
The power circuit uses a tube rectifier, the CLC-π filter, while maintaining the musical flavor of the traditional tube amps. The whole tone of harmony and balance.
By the power transformer secondary output voltage 300V 5Z4P full-wave rectifier, the output the 100Hz unidirectional pulsating DC by the C6, L1, C7, CLC-π filter is stable DC high voltage. The tube rectifier preheating process at boot time experience without the high-voltage shocks, with the role of protecting the tube, and this is particularly important astronomical tube amplifier circuit. CLC-π filter filtering effect, low-power resistance, reduce noise, improve the whole dynamic of great benefit. 220k's role is to protect the C6 220k to the high resistance of the high-pressure discharge resistance. Prevent boot the impact of the high voltage peak pulse voltage on the power tube and output transformer.
Second, the output transformer production
The output transformer is an important component of tube amp circuits, if the self-made conditions are not met, can institutions to buy the finished product. This machine used for the specific parameters of the output transformer as shown in Figure 2. Core for the 66 × 33 z11 0.35 silicon steel sheet, the beginning of a very 3300 circle, divided into two levels. Diameter is 0.18mm; a total of 172 laps sub-divided into three layers, the diameter is 0.82mm. EI silicon steel sheet is left blank air gap of 0.08mm, the maximum operating current of 70mA, power is 8.5W.
Third, the production and debugging
This machine line is simple, with fewer components can be used scaffolding welding, production debugging a high success rate.
Production welding power source and the filament power supply section, power supply normal after welding amplifier circuit should be noted that the no-load power supply voltage slightly higher capacitor voltage must meet the requirements of Figure 1. The figure marked a few test point voltage when I produced the measured voltage can be used as a reference when making small changes in grid voltage should be close to the above test values, so successful goes without saying.
1K can change the whole state, to draw attention to the production process, especially the 47k can not be too much of this machine measured the output power of about 7.5W, the sound quality is pure and mellow, good control of the speaker, and bile ignorant of the rich, musical the full sense.