The developments of Output Transformer were completed in the mid 1950s

As shown here the development of Output Transformer has been completed in the mid 1950s in the US.

Since then there were no significant new developments, as long as I am concern, until KDK developed truely balanced 

R-core KD series in the mid 2010s. With EI core or Double C core structure, high degree of flux balance cannot be achieved.

The flux balance is the key factor to minimize leakage inductance in the OPT. 

 

 

 

1950년대 최고 두뇌들이 개발한 PP 용 OPT 들입니다. 

진공관시대가 끝날때까지 SE Amp 용은 찾아볼수 없습니다

 

이들의 연장선상에서 새로운 이름의 OPT 가 많이 만드러젔지만 모두가 그뿌리는 1950년대 OPT 들입니다

고성능 OPT 사용으로 값싼 Kit 들이 최고의 성능으로 Hi Fi 업계를 압도 했습니다.

 

My concept of flux balance is shown below.

 

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