Audio transformers are wide band transformers. It has two or more windings coupled by a magnetic field. It is available in two different types such as step-up or step-down transformer and unity 1:1 transformer. It is used to step up or step down a signal voltage and increase or decrease the impedance of a circuit. It converts the circuit from unbalanced to balance. It passes audio signals and block signals that are below or above the audio range of 20 - 20,000 Hz.