Amplifiers: how do they work and what types exist?

Understanding a Microphone

• A microphone is a transducer that converts sound energy to electrical signals.

• Different microphones have different methods for collecting sound energy and converting it to electric signals.

• Condenser microphones use capacitors to transduce audio signals.

• The capacitance of a capacitor is its ability to store energy.

Amplification of Sound

• An audio signal is transported to a preamplifier (preamp) to acquire more energy from an external power source while minimizing noise.

• The ratio of the output to the input is called the preamp’s gain.

• Impedance-matching is a key step to minimize noise.

• The amplification is performed by an active component like a transistor.

Violence Amplification

• A bipolar junction NPN transistor consists of a base, a collector, and an emitter.

• The base is configured so that most of the electrons diffuse into the collector, leading to a large collector current.

• The collector is supplied with a high voltage from an external source, creating a strong voltage.

• The output voltage, or the amplified version of the input signal, is measured at the collector.

Power Amplifiers

• Power amplifiers come in multiple classes, each for specific applications.

• Class A and B amplifiers are used in basic sound systems and small studios.

• Class AB amplifiers are used in home theatres and more intensive use cases.

• Class C amplifiers are used in antennae emitting radiofrequency signals at a single carrier frequency.

Production of Loud Sound

• The loudness of the sound produced at the loudspeaker is a function of the power of the input signal.

• The loudspeaker has three basic components: voice coil, external magnet, and diaphragm.