Talk:Filter Curve EQ

Peter 27Aug19: removed for 2.3.3:

• Length of Filter: How many samples of audio Audacity processes in each analysis step. Generally, it's best left at the default value of 4001 (a Filter Length, FFT, size) of around 4000 gives a good balance between frequency resolution and time resolution, for technical (Audacity code) reasons the number must be odd.).
  • At high sample rates the actual time represented by a given number of samples will be less and the frequency bands will be broader so as to cover the increased frequency range. As a result, the green curve will fit to the blue line less closely at any given "Length of filter" than for lower sample rates.
  • If the green curve Audacity uses to perform the effect is very different from the blue curve you created, try increasing the length of the filter. Higher settings will process the audio in a greater number of narrow frequency bands, but may introduce ringing artifacts at very high settings.
  • A shorter filter length may sometimes be preferable. It will take less time to process the effect, and the smoother curve produced may actually sound better, unless you are modifying very low frequencies.

Peter 22Aug19: This alternative way to mange curves is removed for 2.3.3 in favor of just the Manage button

• Select curve: Click the dropdown triangle to select from a list of preset equalizations. These are either your own saved presets (see "Save/Manage Curves" below) or built-in presets, such as filters to remove unwanted low frequencies that could cause poor sound, or the RIAA curve to equalize an LP recorded into Audacity without equalization. A curve will display as an "unnamed" curve if it is not yet saved as a preset, or if it is a modified preset.

There will also be the following instances where curves can only be matched approximately, so will display as "unnamed":

• Your own saved presets will always display with their saved name if loaded in the same mode you saved them in. In "Graphic EQ" mode, only presets saved in that mode will display with their saved name. In "Draw Curves" mode, a curve created in "Graphic EQ" mode can be displayed as its saved name if loaded from within "Draw Curves". If that curve is loaded in "Graphic EQ" mode and then switched to "Draw Curves", it will display as "unnamed".
• Any curve in either mode will display as "unnamed" if there are points in the curve that are outside the range of the Horizontal Scale. For example, if you have a point at 10 Hz in a curve saved in linear view (where the scale starts at 0 Hz) then switch to logarithmic view (where the scale starts at 20 Hz), the curve will switch to "unnamed". In that case Audacity will put a point in at 20 Hz at the dB level you wanted at 10 Hz.

• Save/Manage Curves: This opens the "Manage Curves" dialog described below.