confusion about equalizer, greyed out bands

[mhellwig]

Hello,

just started using easyeffects for the first time because I had an issue with a bluetooth speaker (or maybe just this one audio file, not sure yet) where one specific frequency band was extremely over-present. So I enabled the equalizer in easyeffects, dragged down this one slider (53Hz) and things sounded better. So nice, great.

Then I explored a little more and got confused.
Confusion number one: there's 32 bands. Kinda a lot, Maybe I'd like to have coarser control. So I entered "16" in the "bands" box and sure, the number of bands was reduced. But: I was surprised to see that it's not giving me bands of doubled width to control the whole spectrum again but rather it starts at the lowest frequency (22Hz) with the same step size and then just stops after the 16th band (that's 571Hz).

OK weird but whatever. So I re-entered 32 and got really confused because now it's showing all bands again but all the bands above 571 are greyed out and manipulating the sliders of the greyed out bands has no audible effect. The lower ones still work, though. At this point I hadn't really looked at the upper bands before changing from 32 to 16 so I can't say whether they were greyed out from the start (at this point in time I assumed they were).
But then I did another experiment because I like to probe and so I reduced the number of bands from 32 to 5 and again, It just showed me the 5 lowest bands (so really useless but instructive example, I guess). I re-entered 32 in the "Bands" box and got 32 bands again, but now all the ones above the 5th were greyed out and are without function. So it seems as though reducing the number of bands turns off the bands not shown and re-upping the number of bands doesn't turn them back on.

Quitting easyeffects (verified with pgrep that it's actually gone) and re-starting it doesn't make the bands become active again. Quitting easyeffects and restarting pipewire (using systemctl --user restart pipewire) doesn't make the bands become active again.

Even more weird: rebooting doesn't make the bands become active again.

As a completely extreme example, setting the number of bands to 1 makes there to be just one band, the one at 22Hz (and it is still narrow). Setting the number of bands to 32 again, now all of them except the leftmost one are greyed out.

Since I hadn't tried that before, I also removed the equalizer effect and then re-added it, no change.

So. Uh. Am I holding it wrong? Or what?

[mhellwig]

Oh wait.

I just realized, when clicking on the sprocket wheel icon for a greyed-out band, it is showing "Type" as "Off", whereas for a non-greyed out band, it's showing as "Bell" (I assume that means bell-curve?). Changing this value from "off" to "bell" makes the band become active again.

I also discovered that there is a "reset" button at the bottom of the equalizer (this single button is the only one that isn't labeled with a word but only shows an icon and I hadn't really twigged to it meaning "reset" before) and clicking that makes all the bands active again.

So huh.

I guess that changes my question from "how do I turn the bands on again?" to "why does reducing the number of bands turn off the bands that are not shown while increasing the number of bands does not turn them on again?" And also, as before, "why does reducing the number of bands lead to the same width of bands starting from the lowest one, just removes the upper bands from control, instead of giving me coarser (wider) bands to manipulate? Because that would have been my naive assumption."

[mhellwig]

To maybe better explain my confusion:

When setting the number of Equalizer bands to, say, 3, I would assume to get the equivalent of an old Stereo-Amplifier with three knobs labeled "Bass", "Mid" and "Treble".

[wwmm]

When setting the number of Equalizer bands to, say, 3, I would assume to get the equivalent of an old Stereo-Amplifier with three knobs labeled "Bass", "Mid" and "Treble".

It depends. From a technical point of view what we have is a parametric equalizer and not a graphical equalizer. We do have a button that will calculate each band frequency and bandwidth so that it mimics a graphical equalizer with the same amount of bands. It works well in many cases where ordinary people needs an equalizer. But to the eyes of someone with a formal background in audio signal processing it is not exactly the same thing.

In your case it is probably enough to just click on the calculate frequencies button in the equalizer bottom bar. As this is a parametric equalizer it won't automatically do that. That is why I added this button to help in these cases.

it's showing as "Bell" (I assume that means bell-curve?)

Yes. When trying to mimic a graphical equalizer this is the band type that should be used.