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Re: Large, 1500W RMS, audio amplifier ground.

Discussion in 'Audio' started by edbarx, Apr 4, 2018.

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  1. edbarx


    Sep 28, 2017
    I would like to aks to which point on a large amplifier circuit the ground terminal is usually found. An amplifier that I am trying to understand with the aim of repairing has its ground connected to the audio power output. By the latter, I do not mean, the centre tap of the power transformer, as that, in my logic, should be where the ground should be connected.

    The amplifier is powered by a large toroidal transformer, with two centre tapped secondaries connected to two bridge rectifiers with the centre taps to the point between two smoothing capacitors. This forms a DC power supply as follows:

    -82V ---- 0V ---- +82V (both DC)

    The about is replicated for both channel A and channel B.

    I am completely perplexed as in my entire life (~51 years) I have never met a circuit with such weird earthing.

    The amplifier is a professional public address amplifier.

    I downloaded the service manual from:
  2. dave9


    Mar 5, 2017
    If the center tap of the transformer has its own, locationally isolated lead to this point so it is a star ground config to avoid ground loops, that can work. If it does not, apparently they didn't care or tested and found negligible difference.
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