DIY Tube Preamplifier
- 1). Cut eight pieces of electrical wire. Strip off half an inch of insulating material at the ends of each wire.
- 2). Solder one end of the first wire to the "tip" terminal on the first phone plug. Solder one end of the second wire to the "sleeve" terminal on the first phone plug. Solder one end of the third wire to the "tip" terminal on the second phone plug. Solder one end of the fourth wire to the "sleeve" terminal on the second phone plug.
- 3). Twist together the free end of the first wire with one end of the 1 Megaohm resistor, and solder the twisted wire pair to the grid terminal (pin 2 on the 6CG7) on the vacuum tube.
- 4). Twist together the free end of the third wire with one end of the 100 Kiloohm resistor, and solder the wire pair to the plate terminal (pin 1 on the 6CG7). Solder one end of the fifth wire to the free end of the 100 Kiloohm resistor.
- 5). Solder one end of the 1 Kiloohm resistor to the cathode terminal (pin 3 on the 6CG7). Twist together one end of the sixth wire jointly with the free ends of the 1 Kiloohm and 1 Megaohm resistors, and solder the connection.
- 6). Solder one end of the seventh wire to the first heater terminal (pin 4 on the 6CG7). Solder one end of the eighth wire to the second heater terminal (pin 5 on the 6CG7).
- 7). Attach the free end of the fifth wire to the positive terminal on the 24-volt power source. Attach the free ends of the second, fourth and sixth wires to the negative terminal on the 24-volt power source.
- 8). Attach the free end of the seventh wire to the positive terminal on the six-volt power source. Attach the free end of the eighth wire to the negative terminal on the six-volt power source. Plug the first phone plug into the audio input source (such as an electric guitar or compact disc player output). Plug the second phone plug into the main stage of the amplifier.