[Ardour-Users] what linux audio project do you miss?

John Rigg au at jrigg.co.uk
Sun Mar 6 06:02:31 PST 2011

On Fri, Mar 04, 2011 at 08:50:06AM -0500, Thomas Vecchione wrote:
> 2011/3/4 Jörn Nettingsmeier <nettings at stackingdwarves.net>
> > apart from the delay, linear-phase eqs introduce pre-ringing, so they are a
> > very mixed blessing. they don't change the fundamental truth that you cannot
> > alter the frequency response without altering the temporal response as well.
> > morale of this story: use the minimum eq necessary. the lower the Q, the
> > less phase problems you will get.
> > as david pointed out before, graphic eqs with bands of major thirds
> > necessarily use rather high Qs, and you will suffer their adverse effects
> > even if you set the sliders to "gentle" curves.
> > there is no silver bullet for this problem. or, as jack developer jack
> > o'quin in his infinite wisdom once remarked, "you can't bullshit an
> > electron".
> Correct, but Linear phase EQs are only one possible solution to the problems
> you mentioned.  As I mentioned before there are already very good 1/3 octave
> EQs out there that induce minimal phase problems, even if they aren't
> designed to be linear phase.  The KTs are(Well were, the newer stuff isn't
> quite the same I have heard) standard in the live music circles, far beyond
> simple rock and roll, specifically because they do such a great job, they
> have a great sound, induce minimal phase issues, even with steep
> adjustments, and still do what is needed.  There are others out there that
> are pretty good, but the KTs are probably the best known of the bunch for
> touring shows, and it is more than conceivable that it could be implemented
> in software.
> True you can't bullshit an electron, but we aren't dealing with electrons in
> the same way when dealing with DSP vs analog processing:)

With minimum phase filters (which includes almost all analogue filters)
the phase shift is proportional to the slope in frequency response.

Any analogue 31 band graphic EQ will produce large values of phase shift
on the slopes if the faders are used in isolation. The better sounding ones
might give a smoother phase/frequency response when set to a smooth curve
than others, but there's no escaping the link between phase shift and
slope in the frequency response.


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