Audio Transformers
Audio Transformers
Similar to power transformers in terms of construction but typically much smaller in size, audio transformers — also called audio frequency (AF) transformers — perform an array of critical functions in amplifier circuits spanning the audio band of frequencies that the human ear can detect, typically from 20 Hz to 20 kHz.
Impedance matching is one of the most important functions. For example, a basic vocal amplification setup will include a microphone, cables, and an amplifier input, each of which may have different impedances that can result in signal loss. Using an audio transformer for impedance matching will prevent signal reduction due to impedance mismatching.
Taking this setup one step further, the signal can then go from an amplifier to a loudspeaker. Speakers have low input impedance, while amplifiers have much higher output impedance. Matching them up with an audio transformer facilitates the transfer of maximum power from the amplifier to the loudspeaker. This is how these devices get their name: Audio transformers “transform” the impedance of input and output circuits by raising low impedance or reducing high impedance as needed in order to transfer the maximum amount of AC power between circuits and devices.
Since transformers have the ability to “transform,” or change, the apparent impedance of a circuit input or output, they may be used in several applications that require transfer of the maximum amount of AC power between circuits. Transformers can make a low impedance appear much higher, or a high impedance much lower.
And in audio setups that involve amplifiers and loudspeakers, audio transformers play an important role, ensuring that the AC audio signal reaches the loudspeaker without adverse effects from the amplifier’s DC that can interfere with loudspeaker operation.
These transformers also exhibit great isolation properties. Because there is no direct connection between the primary and secondary windings inside them, audio frequency transformers can provide complete electrical isolation between input and output circuits, such as those between amplifiers and loudspeakers, which helps to improve safety.
Audio transformers are also capable of performing several of these functions simultaneously.
