Powerful power amplifier 02

The circuit of the amplifier is shown in Figure 2-25. It
has the following characteristics:
    (1) The push stage uses a 6N11 electron tube
for parallel push-pull amplification, with good high-frequency response and high signal-
to-noise ratio.
    (2) The final semiconductor power amplifier tube of this amplifier does not
require a regulated power supply. As shown in Figure 2.26,
the LC filter network power supply is composed of a 1. SH/1.5A choke coil and a 20000-1F/50V electrolytic capacitor. ÷
    (3 ) The output transformer is easy to make. When making it yourself, a high-quality silicon steel sheet with a tongue width of 24mm and a stack thickness of 40mm is used as the core. The primary has
a total of 200 turns, which is connected in series by two 100-turn windings ; the secondary uses 100 turns. In actual production, Use two pieces of <1) 0.72mm and one
piece of 1.02mm double-wire high-strength wrapping wire to wind three strands in parallel, identify the heads and tails of the three windings, and then connect the heads and tails of the two <pO* 72mm
windings in series As the primary, the winding of 1.0Zmm is used as the secondary. Insert the silicon steel sheet in a straight line, leaving o. Smm air space.
    (4) Use gallium arsenide light-emitting diodes to provide a 1.9V bias voltage for the final power tube. The operating point of the final power tube is extremely stable.
6 The bias voltage must be adjusted when using other power tubes.
    (5) The amplifier is quite easy to make. This article uses Imm copper plates to make the base, and the scaffolding welding process; the electron tube, transformer
, and large electrolytic are exposed on the base, and other components are installed in the base. The shorter the connecting wires, the better. The output power of
    the amplifier is 15w, and it is used with the self-made HiVi SS6-VA earth-cannon speaker. The positioning is accurate, the string vocals are soft and delicate
, and the sound quality is waxy and powerful. It is especially suitable for listening to Hi-Fi music in a small room.