The power supply unit has to provide all components of the amplifier with the needed voltage and current. The power supply unit is a very relevant component of the entire amplifier. A perfect design of all amplifier stages can be undermined by a poorly designed power supply. A good power supply, for a hi-fi amplifier, has to minimize hum and noise, generally introduced by the power supply rectifier, and has to provide a constant voltage, even in presence of transients requiring a sudden surplus of current.
The power supply unit has to supply electric power to the following parts:
- the (anodes of the) vacuum tubes in the various amplifier stages
- the vacuum tubes heaters
- the vacuum tubes grid, when fixed bias is used
In the following, we will discuss them separately.
