Adjusting Phase from 0 -180 and 180 - 360

Discussion in 'The Projects Forum' started by Sommer, Jun 3, 2011.

  1. Sommer

    Thread Starter New Member

    Jun 3, 2011
    4
    0
    Hey i'm making a Sub Bass Filter.
    And for that I am using a Linkwitz Riley filter for seperating the SW from the W, M and T.
    But I got a problem with the Phase.
    That's why i am looking for a circuit where i can change the Phase of an audio signal with one single Potentiometer. (Trim resistor).
    I found a way, but that is a bessel all-pass filter, that could only give me a delay from 0 - 50 degrees.
    But that is just not enough.
    Any of you know how i can make it?
    An example could be the Hypex DS 2.0
    On that product i can change the phase.
    Anyone know how i can make my own.
    I also found a bessel 2. order all-pass filter. but to change that from low delay to high delay i would have to change 2 resistors at a time. how could i do that with only one potentiometer.? (Trim resistor)
    Or any other helpfull answears is very welcome.
    maybe something completely different.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    One hardly imagines a person can actually hear a phase shift in the sub bass.

    However, if the audio fanatics have convinced you, Wikipedia has a way out -
     
  3. Sommer

    Thread Starter New Member

    Jun 3, 2011
    4
    0
    Ohh forgot to say that i am using a LR4... with 24dB/octave
    that means there is a 360° phase shift.
    But i really want to find a way to adjust the phase.
    that is the primary question.
     
  4. williamj

    Active Member

    Sep 3, 2009
    180
    32
    Sommer,

    In responding, I am engaging in topics outside of my area of expertise. But many decades ago, in an electronics class, I learned a little about the resistive-capacitive (RC) citcuit. You may have already concidered and rejected this train of thought but here goes.

    I don't remember the math behind it but a resistor and capacitor in parallel will delay the phase of an AC circuit. As long as the components are capable of handling the voltages and currents applied in the circuit a RC circuit can change the timing from zero phase delay to 180° phase delay and beyond.

    By varying the resistance you vary the amount of time it takes to charge the capacitor thus delaying the phasing of the circuit. Atleast I think I remember that's how it works. If I'm worng somebody please step in and correct me.

    Good luck

    williamj
     
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