F-Mod's - Put to the test :)

Discussion in 'Archived Threads 2001-2004' started by Chad_A, Aug 12, 2002.

  1. Chad_A

    Chad_A Auditioning

    Jul 19, 2002
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    This is using a signal generator and my qsc rmx850 with a single and a set (specified below) of F-Mod 70hz lpf's.

    Here's a new one with only one in place:

    30hz = 4.1v
    40hz = 3.6v
    60hz = 4.2v
    70hz = 3.9v
    140hz = 2.2v
    240hz = 1.1v

    Not changing anything but the freq. Gain is WAY down on my qsc.

    Once again, that was one fmod in place. here is with both in place:

    30hz = 1.8v
    40hz = 1.6v
    60hz = 1.4v
    70hz = 1.1v
    140hz = 0.3v
    240hz = 0.0v

    Turned the gain up and ran again with both in place:

    30hz = 4.4v
    40hz = 3.6v
    60hz = 3.1v
    70hz = 2.6v
    140hz = 0.8v
    240hz = 0.2v

    I'm not good with the whole figureing out the slope thing, I'll let you guys do that.

    They work fine for me, I'm happy even if they are only 6db/oct each and not 12db... I can live with a 12-13db/oct lpf.
  2. Richard Greene

    Richard Greene Stunt Coordinator

    Mar 5, 2001
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    My measurements showed each FMOD was 6dB/octave, not 12dB/octave, so I had to plug two together for 12dB/octave.

    Each FMOD also reduced overall output 2-3dB ... so using two cascaded reduced output 4-6dB.

    They work when cascaded and I do use them for an inexpensive stereo where an active crossover would be too much money. Their sound quality seems good to my ears when used in an expensive stereo, but I prefer my Marchand XM9 crossover because 24dB/octave is what I wanted.

    A pair of 50Hz. low pass FMODS for less than $30 seem fairly priced ... but not the bargain they would be if they were really 12dB/octave.

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