Small- Signal Audio Design

Chapter 6

Preamplifier Architectures

Some sort of preamplifier or control unit is required in all hi-fi systems, even if its only function is to select the source and set the volume. You could even argue that the source-selection switch could be done away with, if you are prepared to plug and unplug those rhodium-plated connectors, leaving a ‘preamplifier’ that basically consists solely of a volume-control potentiometer in a box. Mind you don’t catch your sackcloth on those heat-sink corners, and try to keep the ashes away from the turntable.

I am assuming here that a selector switch will be required, and that gives us the ‘passive preamplifier’ (oxymoron alert!) in Figure 6.1(a).

Figure 6.1: Preamplifier evolution. (a) Passive preamplifier. ...