Custom Audio Transformer

What’s Audio Transformer?

An audio transformer also known as a low-frequency transformer, is a transformer that operates in the audio range, with a working frequency range generally from 10 to 20000Hz. It is intended to isolate an input circuit from an output circuit and provide filtering to a signal that passes through it. It is commonly used to transform the voltage or impedance of loads. It is an audio device because it is designed to operate on signals with a frequency spectrum in the audible band. In wireless communication, broadcasting, television, and automatic control, it serves as a component in circuits such as voltage amplification and power output. Within its operating frequency band, the frequency response of an audio transformer is uniform. Its core is made of high-permeability material stacked together, and the primary and secondary windings are tightly coupled, so that almost all the magnetic flux passing through the primary winding is linked to the secondary winding, with a coupling coefficient close to 1. The lowest frequency of the passband is determined by the inductance of the primary winding, while the highest frequency is determined by the transformer’s leakage inductance. To ensure that the transformer has a sufficient passband, the inductance of the primary winding should be large, and the leakage inductance should be small. Magnetic hysteresis loss and magnetic saturation of the core can cause signal distortion. Proper load configuration, increasing the load current, can reduce the impact of magnetic hysteresis loss; increasing the cross-sectional area of the core and leaving an air gap can prevent saturation of the magnetic circuit, thereby reducing signal distortion.