Purpose of Spectrum Analyzer -> Flat

Support questions for Neutron Player only.
blaubär
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Joined: Tue Apr 02, 2019 6:48 am

Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Sun Jul 12, 2020 7:24 am

A question regarding the purpose of the new option Settings > User Interface > Spectrum Analyzer > Flat (Make spectrum flat for a pink noise) :
dmitrykos wrote:
Fri Feb 14, 2014 7:22 pm
2.14.4:
* New option UI - Spectrum Analyzer:
- Flat: to switch on/off flattening spectrum for a pink noise;
Pink noise should give a flat curve in the spectrum analyzer using the logarithmic scale, that's how pink noise is defined. So imho having it active is necessary. Can anybody think of a possible reason NOT to have it activated ? ( Playing white noise with the linear scale doesn't make a visible difference one way or the other, so it won't be used for that )

PaBeCa
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Re: Purpose of Spectrum Analyzer -> Flat

Post by PaBeCa » Tue Jul 14, 2020 12:23 pm

how to use this option?

blaubär
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Joined: Tue Apr 02, 2019 6:48 am

Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Tue Jul 14, 2020 1:58 pm

PaBeCa wrote:
Tue Jul 14, 2020 12:23 pm
how to use this option?
I keep it permanently enabled, I wouldn't know why anybody should anytime disable it.

WitzyZed
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Joined: Fri Nov 22, 2019 8:49 pm

Re: Purpose of Spectrum Analyzer -> Flat

Post by WitzyZed » Tue Jul 14, 2020 7:23 pm

I am curious how these options are related:

Say I arbitrarily set the following options:
Screenshot_2020-07-14-14-18-29.png
Screenshot_2020-07-14-14-18-29.png (63.61 KiB) Viewed 2559 times
I click to disable the 'Flat' option, and the scale ratio immediately changes to what seems to be an oddly specific value:
Screenshot_2020-07-14-14-18-34.png
Screenshot_2020-07-14-14-18-34.png (62.4 KiB) Viewed 2559 times
I click to enable the 'Flat' option, and the scale ratio immediately changes to another oddly specific value:
Screenshot_2020-07-14-14-18-39.png
Screenshot_2020-07-14-14-18-39.png (63.58 KiB) Viewed 2559 times
What is the significance of these Scale, Ratio (n) values of 0.505 and 0.615 ?

How are these related to the scale of the spectrum analyzer as it was before this option was even available?

blaubär
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Joined: Tue Apr 02, 2019 6:48 am

Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Wed Jul 15, 2020 6:12 am

Afaik "Scale, Ration(n)" is just a scaling factor, nothing more. "Flat" is two things - another scaling factor, implemented in such a way as two change "Scale, Ratio(n)", and another weighing of the different frequencies. The low ones get amplified, that's probably the reason for the decreased overall scaling. See the representation of pink noise in the logarithmic view with "Flat" enabled :

spect-1.PNG
spect-1.PNG (23.76 KiB) Viewed 2549 times
And with "Flat" disabled :

spect-2.PNG
spect-2.PNG (23.49 KiB) Viewed 2549 times
Pink noise is by definition flat in this view, therefore the "Flat" setting is necessary. ( and I wouldn't know why ever to disable it :D )

blaubär
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Joined: Tue Apr 02, 2019 6:48 am

Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Wed Jul 15, 2020 6:19 am

For the linear scale it looks like this with white noise :

spect-3.PNG
spect-3.PNG (24.35 KiB) Viewed 2548 times
Here the deactivation of "Flat" isn't recognizable in the relative strength of the representation of the different frequencies, but only due to the decreased scaling :

spect-4.PNG
spect-4.PNG (23.03 KiB) Viewed 2548 times

blaubär
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Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Wed Jul 15, 2020 6:29 am

WitzyZed wrote:
Tue Jul 14, 2020 7:23 pm
How are these related to the scale of the spectrum analyzer as it was before this option was even available?
This correction for the logarithmic scale seems to have been introduced with version 2.08 :
dmitrykos wrote:
Fri Feb 14, 2014 7:22 pm
2.08.0:
[...]
* Improved:
- spectrum Log scale: flat for pink noise to show low and high bands with equal power;
And I would think the "Flat" option is just the subsequently implemented switch for that.

blaubär
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Joined: Tue Apr 02, 2019 6:48 am

Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Wed Jul 15, 2020 6:41 am

... and if you look at pink noise ( as a representation of real music ) with the linear scale ( not that this would be sensible :D ) with "Flat" enabled :

spect-pink-log-flat.PNG
spect-pink-log-flat.PNG (24.23 KiB) Viewed 2542 times

And without "Flat" :

spect-pink-log.PNG
spect-pink-log.PNG (23.55 KiB) Viewed 2542 times
So I think there are people who like to watch the spectrum in the linear mode ( why ever ? no idea ! ). And with the introduction of the "Flat" correction without the switch in 2.08.0 for them the spectrum in the low frequencies shifted into the red. So now they can either disable the correction or just scale down.

blaubär
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Re: Purpose of Spectrum Analyzer -> Flat

Post by blaubär » Wed Jul 15, 2020 9:39 am

Get yourself some sine-sweep-testtones and play them with spectrum sensitivity = 1. You'll see that with "Flat" activated the amplitude remains constant, as one would expect. As the sweep has a constant amplitude, that's another argument to always keep it activated.

WitzyZed
Posts: 211
Joined: Fri Nov 22, 2019 8:49 pm

Re: Purpose of Spectrum Analyzer -> Flat

Post by WitzyZed » Thu Jul 16, 2020 12:45 am

I have no problem with it being activated (my first "arbitrary" settings are the ones I specifically use). You don't need to defend the "flat" option. I'm on your side. I am just wondering why it resets the scale value to something seemingly random yet specific by deselecting and selecting that option . . .

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