Audio Transformer Frequency Response

The low-frequency response of an audio transformer is down 3dB compared to mid-frequency response at the frequency where the inductive reactance of the primary winding equals the primary operating impedance. The low frequency cut-off can be lowered by reducing the operating impedance. There are three ways to do that. The primary source impedance, the secondary load impedance, or both can be lowered. Lowering the primary source impedance will roll-off the high-frequency response. Lowering the secondary load impedance will raise the secondary Q and peak the high-frequency response. Lowering both similar amounts will lower the low frequency cut-off with minimal effect on high-frequency response. ©2004 Tigertek, Inc. All rights reserved.

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