Eq principes

[HeavyFranz]

Hi @ all! Merry Christmas ! I'm a student in elett.engineering and i'm studyng iir, fir filter and dsp principles. I've buyed a mic...ok not very good the lem lm20 and i've the freq.response printed on a paper. I'd like to draw "automatically" a curve to flat my mic. I've found Eqcurves.xml and i've tested some things but audacity crashs when i modify the file, perhaps i can't give f=0.00 d= 0 and f= 10000 d=6, i think because the plot of the cosine in fir/iir filter...can i have some help for understanding how eq in audacity woks?
Thanks in advance!
Byeee!

[kozikowski]

http://wiki.audacityteam.org/index.php? ... rogramming

Koz

[steve]

As suggested by the file extension, Eqcurves.xml is an XML file.

XML files can be edited as "plain text" but you need to take care that you keep the correct structure.

Each section of the file is defined by "opening" and "closing" "tags".

If you look at the default Eqcurves.xml file you will see a structure like this:

Code: Select all

<equalizationeffect>
	<curve name="curve-name">
		<point f="30.0" d="-20.0"/>
		<point f="100.0" d="0.0"/>
                .......
	</curve>
</equalizationeffect>

"<equalizationeffect>" is the opening tag for the complete set of presets.
"</equalizationeffect>" is the matching closing tag (note the forward slash)

<curve name= ""> is the opening tag of one preset and </curve> is the matching closing tag.
Each preset must be enclosed within an opening <curve= "name"> tag with a unique name and a closing </curve> tag.

Within the curve preset, each point is identified with a frequency (f=) and a gain setting (d=)
The gain setting is in dB.

[whomper]

i assume dB means +/- from 0 level which is NO eq at all

so +dB increases that freq
and -dB lowers that freq

how many bands should be used ?
31? 3?

any way to adjust the Q?

I am guessing this is a sort of british eq and not parametric

I am guessing you need the decimal and the zero to tell it to use FLP not binary

[steve]

@whomper
The Eqcurves.xml is used by the "Equalization" effect in the main "Effect" menu of Audacity 1.3.x.
The list of points in this XML file are the "co-ordinates" (frequency and dB values) of the points that are shown on the "Draw Curves" view.