hifisonix

Tag: class B

  • Barney Oliver: Crossover Distortion in Class B Audio Amplifiers

    This is the famous analysis of class B amplifier cross-over distortion by the then head of HP Reasearch Labs, Dr. Barney Oliver,  published in the February 1971 edition of the HP Journal.  The  bias current Iq for a class B emitter follower amplifier is shown to be approximately  Iq = .026/(Re+re+(rb/hFE)). In practice,  – the…

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  • The Quad 405 Current Dumping Amplifier from 1975

      The famous Quad 405 ‘Current Dumping’ amplifier was launched in the mid 1970’s, and featured feed forward error correction that effectively removed the class B cross over distortion that plagues this type of output circuit structure. The design featured no adjustments in production, but the circuit components around the output (L2, R36, R38) had…

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