Member Since: August 14, 2011

Country: United States

  • Looking at the schematic, I see R1 and C1 forming a high pass filter, followed by C3 and R5 forming a low pass filter. The general equation for RC filter corner frequencies is

    3db corner freq in hz = 1/(2 * Pi * R in ohms * C in farads)

    I calculate (better check my math!)

    high pass = 1/(6.28 * 2.210^+3 * 4.710^-6) = 15.4 Hz

    That sounds reasonable unless you want infrasound.

    low pass = 1/(6.28 * 1010^+3 * 1210^-12) = 1,300,000 Hz

    That sounds a little high to me for audio!

    If they used C3=12 nanofarads instead of picofarads the low pass would have been 1,300 Hz, which is in the audio ballpark.

    I wonder if there is a typo in the schematic, or if the circuit is incorrect? Again, better check my analysis!

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