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Low freq bump on HPFs

Discussion in 'Pro Audio Equipment' started by Marcelo, Jul 25, 2002.

  1. Marcelo

    Marcelo Guest

    Hi!, Í wanted to know if anybody could explain why is there a low freq. bump when applying HPF to sources on mixing. My experience is that sweeping on the low range I can find a cutoff freq that, not only removes energy, instead it increases presence.
    In other words, by removing low freq rumble I actually can have more Low or mid low presence.
    I notice the effect more dramatically on percussion chanells like snare, mostly around 80 Hz.
    Be it Pro Tools, the Sony DMXR100, or whatever, there is a cutoff freq that can make this happen.
    Am I missing something?
  2. RecorderMan

    RecorderMan Distinguished Member

    Mar 28, 2001
    Hi Marcelo,

    First, cutting frequencies can let other bands in the spectrum be heard better. Second, many filters (even digital models...filter bank as an example) mimic the way transformers work. At the knee frequency (where the dip starts to happen....usually noted at the point 3db down into the cut) Transformers-depending on there characteristics- can "ring" or oscilate ever so slightly, thereby causing a reinforcement or "boost" around that frequency. Playing with this is definetly one of the things ou use/listen for when filtering.

    An extrapolation on this, is to filter and also boost on another bell shaped EQ at frequencies at or jsut beloe the filter freq's. Great for gtrs.
  3. Marcelo

    Marcelo Guest

    Thank you!!!, It is funny!, because I do that a lot on GTRs, Removing Hi freq,and compensating with a slight boost below the cutoff.
    Feels like on going the right direction.
    Greetings from Argentina.
  4. RecorderMan

    RecorderMan Distinguished Member

    Mar 28, 2001
    Back at ya' from LA :w:

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