Re: Audio Transformers are like Monster Cables


"Harry Dellamano"


John, I am doing circuit design, not hooking up audio boxes. Believe me,
the load is 90R at 10mW so that is 0.95Vrms. To be most efficient I want
the lowest loss in the transformer. Matching loads to sources is
overrated. It will give you max power transferred at 50% efficiency but
who can live with all those losses.


** How confused is this cretin ?

Maker's rated load impedance value for an audio band transformer is the
*OPTIMUM* load impedance.

It is optimum firstly in terms of frequency response - when underloaded
expect to see a HF response peak, when overloaded expect to see an early HF
roll off.

Efficiency ( within the pass band) depends mainly on the ratio of winding
resistance to load impedance - typically that ratio is about 10 to 1 but
may be higher.

Eg: the F28045 1:1 ( turns ratio) tranny is rated at 100 ohms impedance and
has 12 ohms resistance in each winding - so efficiency will be around 80 %.


It is much better to use the lowest Z transformer that can support your
volt seconds.


** No, the correct design procedure is to use a tranny with no better LF
performance than needed for the app and operate it at the maker's rated
impedance.


This is just between circuit designers but don't try to convince your audio
crowd that.


** Audio designers know what they are doing.

Been routinely getting high efficiency, low distortion and ruler flat
response over a frequency ratio greater than 1000 to 1 for the last 70
years.




....... Phil




.

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