Practicing with a headphone amp is convenient. A typical headphone amp is portable and enables you to play without disturbing neighbours or roommates. If you plan on building your own amplifier, a tube headphone amplifier is a good place to start. The circuits are typically simpler than complex multichannel amps and the power requirements for headphones are lower. The presence of the tube ensures that the tone does not suffer despite the power rating. You can get all the necessary parts by purchasing a self-assembly tube headphone amplifier kit.
Set up a work area. This must be well lit and well ventilated. There must be a power source for your soldering iron.
Inspect the parts. Use a magnifying lens to check the tubes for cracks. Check the resistor and capacitor values and make a note of them.
Study the schematic. Make a note of the board-mounted component values.
Fill the circuit board. This is where the signal processing occurs. Fit each part into its specific turret according to the schematic. Push the component in so the connectors protrude through to the other side. Typical amp kit board components include resistors, capacitors, tube bases and op-amp chips. Once you have loaded all the board-mounted parts, place the board face down and solder the connector legs to the brass rails that run along the board.
Install the finished board. Solder it into the base of the amplifier chassis.
Connect the IEC power supply. Mount the power block in the predrilled square hole on the chassis. Solder the red wire to the positive board point and the black wire to the ground board point.
Solder the input jack to the op-amp chip. Push the front of the jack through the predrilled hole in the front or side of the chassis. Solder the red and black wires to the eyelet directly connected to the op-amp chip.
Load the potentiometers through the predrilled holes on the front of the chassis, inside to out so the potentiometer poles are sticking out. Cut a 3-inch piece of wire for each potentiometer and strip the ends. Solder a piece of wire to each potentiometer and solder the other end to the correct point on the board, following the schematic. Load the tubes into their bases.
Connect the headphone wire. Solder this to the output point on the board, referring to the schematic for guidance. Feed the wire it through the notch on the chassis and tape it to the outside of the chassis for easy access.
Enclose the chassis. Screw the lid down onto the base. Fit the dials onto the potentiometer poles. Make sure that zero on the dial lines up with the notch on the pole.
Use a set of coloured markers to colour-code parts on the schematic with the physical component in the kit.
Wear latex gloves to handle the tubes. Oils on your hand can contaminate the glass.
Tips and warnings
- Use a set of coloured markers to colour-code parts on the schematic with the physical component in the kit.
- Wear latex gloves to handle the tubes. Oils on your hand can contaminate the glass.