About power amp distortion.

Discussion in 'High End Audio' started by Gaetan Mailloux, Aug 10, 2003.

  1. Hi

    How come some fast slew rate power amp can have a so big raise of
    distortion in high frequency (5 khz and up) ?

    What made a power amp to have a much higher distortion at high frequency ?
    TIM distortion ? or ???

    Thank you very much

    Bye

    Gaetan
     
    Gaetan Mailloux, Aug 10, 2003
    #1
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  2. Gaetan Mailloux

    chung Guest

    In general, distortion goes up as a function of frequency because the
    loop gain decreases. If you look at a power amp's open-loop frequency
    response, there is usually a roll-off such that the gain at 20KHz is
    much less than that at 1KHz. Loop gain is the difference between
    open-loop gain and closed-loop gain. Loop gain is what drives the
    distortion to zero, or as low as possible, in a feedback amplifier.

    The slew rate determines the power bandwidth of the amplifier. If the
    slew rate is insufficient, then there will be distortion at high output
    levels at high frequencies. But slew rate by itself does not guarantee
    low distortion, it's just a necessary condition.

    TIM is just another way of stating slew-rate induced distortion in
    feedback amplifiers.
     
    chung, Aug 11, 2003
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  3. As a general rule, they don't. Do you have specific example in
    mind?
    Generally the linearity at high levels and high frequencies is
    due to high frequency limitations in teh dveices used.

    But your statement that high=-slew rate amplifiers have high
    distortion at high frequencies simply doesn't hold.
     
    Richard D Pierce, Aug 11, 2003
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