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Audio clipping/distortion cause?

Discussion in 'Electronic Basics' started by John Robertson, Nov 19, 2003.

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  1. What is the cause of audio clipping in a transistorised amp? Is it a
    underpowered transformer not providing enough voltage/current to the
    transistors, too much voltage/current to the transistors, or the transistors
    themselves need higher voltage/has too much voltage (not transformer fault)? Or
    something totally different?

    I keep reading about amps getting into "overdrive" which causes the clipping,
    but don't understand what this is. I have also read that valve amps have a more
    soft clipping, while transistorised amps have a more hard clipping. Is this
    correct?

    If it is something as simple as a transistor getting too much voltage/current,
    couldn't one then just lower the voltage/current to the transistor to stop or
    at least lower the amount of clipping/distortion?
     
  2. Lord Garth

    Lord Garth Guest

    If the gain x Vin is greater than the available power supply, you get
    clipping.
    You can lower Vin or lower the gain and you could resolve the problem
    unless that form of distortion is desired as in an effects pedal.
     
  3. By this, do you mean if the voltage input requirement for the transistor is
    higher then what the power supply can supply, that the clipping will occur?
    I'm not really understanding what you are saying, I'm sorry. I'm new to
    electronics and trying hard to understand. It sounds like you are saying to
    lower the voltage inputted to the transistor, will result in the clipping to
    stop (or at least be reduced), but also that the requirement of the transistor
    for voltage is more then what the transformer can put out.

    For example, the transformer puts out 6 volts, but the transistor requires 9
    volts, so because it's not getting 9 volts, the clipping is occuring. Is this
    what you mean?
     
  4. Lord Garth

    Lord Garth Guest

    It is a bit tough but a transistor by itself is no more an amplifier than a
    CPU
    by itself is a computer. This means that if a circuit is designed to a
    particular job
    and if you try to make it more that the design is capable of, you will get
    distortion.
    That distortion is called 'clipping'.

    An amplifier usually outputs a bigger, faithfully reproduced copy of its
    input.
    If a sine wave of 1 volt is the input and the gain is 10, the output should
    be a
    sine wave of 10 volts...suppose the power supply is only 9 volts...the
    output
    would be fine from 0 to 9 volts but from there, it could do no more, the
    output
    is at maximum and so the area that would be from 9 volts to 10 volts would
    be 'clipped' off.

    Suppose now the input is a sine wave of .5 volts, the gain of 10 would
    produce
    an output of 5 volts and all would be well with a 9 volt power supply.

    Suppose the input was again a 1 volt sine wave but the gain was 8, the
    output
    would be an 8 volt sine wave and again, all would still be well.
     
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