LM386 guitar amp

Discussion in 'General Electronics Chat' started by jeffblev, Jul 12, 2009.

  1. jeffblev

    Thread Starter New Member

    Jan 1, 2008
    I see a lot of LM386 based simple guitar amplifier circuits like the following:


    The national datasheet states that the input is referenced to ground but that the output is referenced to 1/2Vcc. If your input is referenced to ground though, won't this clip a guitar signal?

    What am I missing?

    Thanks :)

  2. Audioguru


    Dec 20, 2007
    The LM386 is a power amplifier, not an opamp.
    It is designed to be biased correctly when its input is at 0V and when it has a single supply polarity.

    It has built-in negative feedback that keeps its output DC voltage at half the supply voltage for maximum output swing. The negative feedback sets its gain at 20 (or at 200 if a capacitor is added between pin 1 and pin 8) and reduces its distortion.

    It has symmetrical clipping like any audio amplifier.
  3. jeffblev

    Thread Starter New Member

    Jan 1, 2008
    Thanks AudioGuru :)