Theory and Practise of Wide Bandwidth Toroidal Output Transformers

Menno Van Der Veen

The frequency range and time behavior of output
transformers, used in tube amplifiers, are determined by the transformer
parameters and the impedances of the source and the load. A general theory
will be discussed on how to calculate the frequency range and time behavior
of output transformers in conjunction with output tubes and loads. A new
Frequency Decade Factor will be introduced and compared to the well-known
transformer Quality Factor, taking the influences of different source and
load impedances into account. A new toroidal output transformer with a -3dB
bandwidth from .3Hz to 250kHz will be discussed.