Equaliser 'Q-bandwith to octaves' look-up table

Discussion in 'Mixing and Mastering' started by paraplu020, Oct 15, 2012.

  1. paraplu020

    paraplu020 Banned

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    hi i think this could be useful for precise almost surgical eq'ing, but this shit is sooo hard to digest... :(

    maybe some whizkid in here can explain it to me in basic english? *yes*
    also this article talks about a bandpass filter, but could this rules be applied to more kind of filters too?

    http://www.rane.com/note170.html

    also...

    http://www.sengpielaudio.com/calculator-bandwidth.htm

    Thanks yo!

    Greetings from Amsterdam! :wink:
     
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  3. Baxter

    Baxter Audiosexual

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    The higher the Q (as in Quality value), the more narrow the bell is. With the highest Q value you can eliminate/boost specific notes/frequencies. If you want to eliminate certain notes/noises/etc, try notch filter (or comb filter for that matter).
    It's that simple.
     
  4. fiction

    fiction Audiosexual

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    I suppose it's handy to have a table handy with some Bandwidth/Octaves to Q-factor mapping, because some VST's show the EQ slope as Q values, while others show them as fractions of octaves. It's not a simple 1/Q formula, hence the sence for a table (My Lord, hath I stated thy statement just a few centuries earlier :-P)

    To explain the matter a bit (somewhat simplified to ease its proper digestion):
    There are 2 common Equalizer types - graphic and parametric.
    Graphic EQs have bands with fixed frequencies and fixed bandwidth. Common models have 7, 10 (octave), 15 (2/3 octave) or 30 (1/3 octave) bands.
    If you divide the audio frequency spectrum (which is about 20Hz to 20.000Hz) into octaves, you get about 10 octaves. A 10-band graphic EQ therefore has 1 band per octave, while a 30-band (or 1/3 octave) EQ has 3 bands per octave, e.g. 100Hz, 125Hz, 150Hz, then 200Hz which is exactly one octave over 100Hz.
    The more bands the EQ has, the finer the problematic frequencies can be corrected. Also, with more bands within an octave, the frequency area (or width, bandwidth) covered by one band is much narrower in a 30-band EQ than in a 10-band EQ.
    Since the fixed frequencies of graphic EQs are rarely where you need them, mankind invented the Fully Parametric EQ which allows for both seamless adjustment of the center frequency, as well as seamless adjustment of the bandwidth of each band. This allows for near-perfect correction of peaks and valleys in any frequency response, given that the EQ has at least as many independent bands as the frequency response has peaks and/or valleys you'd like to correct or deliberately distort.
    If you have a parametric EQ, just play with it using simple noise as input source. Tweak all knobs of one EQ band around the mid range frequency and listen what happens. This will explain more than all words.

    A nice free 10-band fully parametric EQ to learn with can be found at http://rekkerd.org/matthew-lindsay-ncl-eq/,
    another nice and free but more Frequency-Response-oriented 5-band parametric EQ is the NyquistEq at http://magnus.smartelectronix.com/#NyquistEq.

    You can even run them live without a DAW using SaviHost from http://www.hermannseib.com/savihost.htm.
    (Just copy and rename savihost.exe to "EQ-dll-name".exe in the same folder, then run the exe, and it will load the dll with the same name.)
    Only works with a full-duplex audio interface, btw.

    Good luck!


    Otherwise, well and practically-useful explanation from Baxter.
    Wait a minute, Baxter? Sounds like Baxter EQ ... which itself sounds like Varosound?
     
  5. paraplu020

    paraplu020 Banned

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    ok i see what's it's all about and it's not at all 'difficult to digest' :)

    thanks for your explanation guys... (damn, who need audio schools when you have great forums like these anyway :P)
     
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