Line output audio transformers

Line output transformers with silicon iron C cores.

General properties

Compact
Low copper resistance
High level capability
For balance or unbalance drive
Lundahl silicon iron C cores

Driving circuitry for line output transformers should have low output impedance. In order to reach the very best performance in terms of low distortion and low line output impedance, we recommend that our output transformers are used with mixed feedback drive circuitry for negative output impedance and best THD performance.

In the book “OP AMP APPLICATIONS” (Analog Devices, edited by Walt Jung) the use of (op amps and) audio transformers in line input and output applications are discussed in depth. In particular the mixed feedback drive circuits for line output transformers are analyzed in great detail. We strongly recommend the book for anyone who is designing with op amps in general, and in particular if you are designing circuits for transformer line output applications.

The book is available on-line at https://www.analog.com/en/education/education-library/op-amp-applications-handbook.html. The mixed feedback circuitry is discussed in Section 6 (3.2Mb), page 6.71 and forward.

Sectioning of transformers are discussed in a separate paper.