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I'm uncertain how to show the waterfall in a right way and need some clear direction how to adjust it correctly.

Also would be great if someone could briefly explain how to read/interpret the waterfall. I'm not totally oblivious to what it shows, but would probably benefit from a good explanation.
 

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I'm uncertain how to show the waterfall in a right way and need some clear direction how to adjust it correctly.

Also would be great if someone could briefly explain how to read/interpret the waterfall. I'm not totally oblivious to what it shows, but would probably benefit from a good explanation.
The waterfall shows the time it takes low frequency signals to decay (fade to nothing), so you want a fairly high SPL signal when measuring for a waterfall. Typically you’re only concerned with ~ 300 Hz and below, and want to see decay times down to the room’s noise floor. Looks like you have a fairly quiet room, so you might set your vertical graph limit for 25 dB at the lower end.

As you can see from your second graph, you have fairly long decay times in the low frequencies. This is perfectly normal. You can extend the time window out to 600 or even 1000 ms to see how long it takes the signal to decay. This post may be helpful to help understand the relation between signal levels and decay times.

Waterfalls are good for detecting room modes. For instance, it looks like you have one at ~40 Hz. Notice how much longer it takes for the peak at 40 Hz to decay compared to the peak at 60 Hz. This post gives more info about modes and how parametric equalization can minimize them.

Treatments like bass traps can have a dramatic effect on decay times, as you can see from these two graphs.






Anyway, hope this helps. :D

Regards,
Wayne
 
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