Lower Noise Floor Peaking EQ?

Discussion in 'Effects and the DSP' started by Chester01, Jan 18, 2005.

  1. Chester01

    Chester01 New Member

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    Is there a way to reduce the noise floor of the peaking EQ? Im getting aound -75.5 db (however I like to have it be -Inf when im not playing ANY sound through the card) Any ideas? I did notice that if i play something through the card and pause it, sometimes it goes to -Inf and sometimes its -75.5 is it really going to -Inf but Peak is reporting otherwize? Thanks!

    -Matt
     
  2. Soeren_B

    Soeren_B kX Project DSP Engineer

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    Hi,

    I am sorry, but I can not reproduce this. Do you have any plugins before the Peaking EQ?

    /Soeren
     
  3. dj_stick

    dj_stick Apple Fanboy?

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    imo, this is just the AC97 input noise floor

    mute the ac97 fader and see if it is still there
     
  4. Chester01

    Chester01 New Member

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    well its wierd, sometimes it goes to -76 db, sometimes that in one channel and -Inf in the other channel and sometiems it goes to -Inf in both, the order that audio is going into the plugin is p16v->stereo mix ->gain Hq (im adding negative gain with this, not positive) ->Peaking EQ, I can play something into the Peaking EQ and then disconnect the gain HQ plugin (so it has no input) and still Peak shows a -76 db noisefloor. Could this just be a peak plugin problem?
     
  5. Soeren_B

    Soeren_B kX Project DSP Engineer

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    It has been ages since I wrote the EQ plugins, but IIRC the plugins will end up outputting zeroes after a while (few samples) if the input becomes zeroes. The only way it can keep outputting samples is if:

    1) There is input

    2) It is giong into self-occilation (which is unlikely because then the signal would increase unless you are pretty damn precise with your input - which has to present for this to happen, so I guess this rules out this one).

    The plugin is an implementation of a Direct Form 1 biquad filter in which the incomming samples are multiplied in each section of the formulae. So, if the input is zero the output is zero (after some samples).

    /Soeren
     
    Last edited: Jan 24, 2005
  6. Chester01

    Chester01 New Member

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    yea i cant actually HEAR the noise but Peak says its there
     
  7. dj_stick

    dj_stick Apple Fanboy?

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    you have to really crank your speakers to hear it
     

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