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Re: [regsaudioforum] Question regarding Q width statement found in an article

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  • Fred
    Found a link with a calculator that looks useful. http://www.sengpielaudio.com/calculator-bandwidth.htm 0.1442 of an Octave looks close ... Fred. ... Found a
    Message 1 of 5 , Mar 22, 2013
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      Found a link with a calculator that looks useful.
      http://www.sengpielaudio.com/calculator-bandwidth.htm
      0.1442 of an Octave looks close
      :-)
      Fred.



      From: Alan Jordan <aljordan@...>
      To: regsaudioforum@yahoogroups.com
      Sent: Friday, 22 March 2013, 15:40
      Subject: [regsaudioforum] Question regarding Q width statement found in an article

       
      Hello,

      The following quote is from one of the articles by Michael Gerzon that
      Robert Jorgensen linked to the other day:

      "even the frequency response errors can only be corrected to a limited
      degree due to the one-third octave resolution of typical graphic
      equalisers, which is coarser than the critical-bandwidth resolution of
      the human ear. Empirical experience of equalising PA systems with
      parametric equalisers suggests that equalisers with a Q of about 10
      are required to tame simple frequency response effects well
      subjectively."

      My question is, what is a "Q of 10" in terms of octave width? Is it
      1/10th of an octave?

      Thanks,
      Alan


    • Robert
      This is correct(what Ted says). Some confusion can arise because some people call the bandwidth of a filter what is really one-half the bandwidth! This is
      Message 2 of 5 , Mar 22, 2013
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        This is correct(what Ted says). Some confusion can arise because
        some people call the "bandwidth" of a filter
        what is really one-half the bandwidth!
        This is wrong but people sometimes do it
        What Ted is giving you is the right thing.

        Gerzon was not averse to making completely
        unsubstantiated statements. I do not
        think he had any real idea at all based on
        solid evidence of
        what kind of Q versus what kind of amplitude
        error needed correcting. This is a complicated
        thing --wide band errors(low Q) have lower
        thresholds than narrow band errors(high Q),especially
        on music material, and peaks
        have lower thresholds than dips. What you need to make
        things sound neutral is a complex issue.

        Gerzon is pretending to information he did
        not have here(mathematicians are prone to this--
        they are so sure they are right! and they
        usually are --about mathematics/ But psychoacoustics
        is a hugely complex subject and knowing mathematics
        does not make one know psychoacoustics. Improvisation is
        the word for what is going on here. Gerzon,
        for all the interest of his writings, is
        full of this kind of stuff--made up and
        he loves to claim authority. I did not know
        him personally but he comes across as opinionated
        and doctraire about complex issues, even though his stuff
        makes interesting reading.) If you want to know
        something closer to real answers about these questions
        you could try Toole and associates--they too are opinionated
        about what speakers ought to do(and in a rather
        inane way) but their threshold work is ok I think.


        REG

        --- In regsaudioforum@yahoogroups.com, "Ted Rook" <rooknrol@...> wrote:
        >
        > A simple answer is "pretty sharp" ie, narrow bandwidth.
        >
        > Q is the center frequency (number of Hertz) divided by the width of the curve (number of
        > Hertz) at the -3dB points either side of the center frequency.
        >
        > eg With curve bandwidth 1000Hz (at the -3dB points) and filter center frequency 1000Hz,
        > Q=1.
        >
        > This is for resonant circuits having symmetrical frequency response curves.
        >
        > Ted
        >
        > On 22 Mar 2013 at 11:40, Alan Jordan wrote:
        >
        > > Hello,
        > >
        > > The following quote is from one of the articles by Michael Gerzon
        > > that
        > > Robert Jorgensen linked to the other day:
        > >
        > > "even the frequency response errors can only be corrected to a
        > > limited
        > > degree due to the one-third octave resolution of typical graphic
        > > equalisers, which is coarser than the critical-bandwidth resolution
        > > of
        > > the human ear. Empirical experience of equalising PA systems with
        > > parametric equalisers suggests that equalisers with a Q of about
        > > 10
        > > are required to tame simple frequency response effects well
        > > subjectively."
        > >
        > > My question is, what is a "Q of 10" in terms of octave width? Is
        > > it
        > > 1/10th of an octave?
        > >
        > > Thanks,
        > > Alan
        > >
        > >
        > > ------------------------------------
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        >
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