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"Fluttering" noise when moving OP 2 Level Knob (connected with FRFR)?

Discussion in 'Axe-Fx II Discussion' started by dabert, Sep 13, 2013.

  1. dabert

    dabert
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    Hooked up my new FRFR active cab to OP 2 (OP 1 is connected via XLR to a Monitor line mixer). All is fine except when changing volume with the Axe OP 2 Level knob, a "fluttering" noise can be heard - only when the knob is moved.

    When the FRFR cab is connected to OP1 (same cable, unbalanced sockets), this fluttering noise is not present.

    Settings:
    Copy OP1 to OP2, OP2 sum L/R
    TRS cable between Axe OP2 and FRFR cab

    I have tried several configs, including using a TS cable, not copying OP1 to OP2, different settings for OP2 - to no avail - this noise is always there, when moving the Level knob..

    Any ideas or advice?

    Thanks in advance,
    Robert
     
  2. mrstrat

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    I think this is "normal", mine does exactly the same thing.
     
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  3. Patzag

    Patzag
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    Same here. The noise is due, as far as I recall, to the fact that the volume knob is actually a "soft" knob and what you hear is equivalent to zipper noise.
    The setting should not really have to be changed mid gig and is not intended to be altered "musically".
    At some point in the past, the volume did not ever reach 0 and various tapers were experimented with.
     
  4. FractalAudio

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    That's normal. The output "pot" is actually a ladder of discrete resistors that is remotely controlled by the knob on the front panel. Other products simply reduce the digital signal going into the D/A converter but this is sub-optimum as you reduce your dynamic range when doing this. The Axe-Fx II strives to keep the signal into the D/A as high as possible for optimum dynamic range and then controls the output level using a programmable output gain.

    The downside of this approach is that you will hear a small noise when the output switches between the resistors in the ladder.
     
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  5. groovenut

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    ...
     
  6. dabert

    dabert
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    Thanks much all for your quick replies! I am happy to know that everything is ok.

    Out of curiosity: Why does the same thing not happen with /apply to the OP1 Level knob? Different mechanism?

    My setup works without issues now with an expression pedal sending cc12 (OP 2 Level) - max volume level set on the FRFR cab (currently around 10 o'clock), max volume level set on the Axe OP2 level knob (currently around noon) so now I can control output volume on the FRFR cab between 0 and the respective max volume setting easily and without noise, meaning from 0 to ears bleed.
     
  7. NMG

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    The fluttering can be heard on each out with each of the respective output knobs. Output 1 knob flutter is heard on output 1 and so on...

    Sent from my GT-I9100 using Tapatalk 2
     
  8. dabert

    dabert
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    That would make sense - just, that I hear no flutter in any config from OP1...
     

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