Single-ended amplifier circuit fabricated by EL34-B tube super linear connection

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Single-ended amplifier circuit fabricated by EL34-B tube super linear connection

The front stage of this line uses 6N9P-J to connect to SRPP line, but with slight modification, R4 and R6 are connected in series. The signal voltage Eg2 formed on R4 is introduced into the gate of V2 through C2. Adjusting the value of R4 can adjust Eg2, R4. The formed self-supplied gate negative pressure E1 terminal is a V2 cathode, and the negative pole is connected to the V2 gate via R5 to form a self-supplied gate negative voltage circuit, and R4 is independent, and C3 is connected in parallel to make no voltage drop across R4. This modification greatly reduces nonlinear distortion and also reduces the output impedance and better coupling with the back pole. In the process of the welding machine, since the 6N9P is a high-gain tube, the wiring must be reasonable, especially the filament line, and the twisted-pair shielded wire is used, and the trace is as close as possible to the power amplifier tube.

The cathode power of the latter stage is 160Ω (5W), the cathode voltage is 18V, and the screen is connected to the 0.43 tap. The output transformer adopts 38mm×50mm Z-11 silicon steel sheet, layered and segmented. The primary is φ0.27mm QZ-1 type enameled wire wrapped around 2400T, the secondary is φ0.82mm enameled wire wrapped around 124T (8Ω), 8BT (4Ω). The super linear tap starts from B+ with 1032T taps and the gap is 0.24mm. The layer is insulated with cable paper between layers, and then dipped in paint to be installed.

The power transformer power can be more than 150W, and it is wound by 35mm×55mm Xidian silicon steel sheet.

After the installation is completed, check the line is correct and connect to the power measurement. When measuring the voltage value, insert 5Z3P first, then measure the other tube's screen high voltage, 10% higher than the design value is normal, then insert the front stage and the power amplifier tube in turn. Finally, the working points of the front and rear stages are measured. If they are normal, they can be connected to the CD and the speakers. The CD is the Sony D-EJ1000, and the speaker is a 5-inch two-unit sealed type.