Strange Plot with sampled signal

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robschroeder
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Strange Plot with sampled signal

Post by robschroeder » Sat Nov 05, 2016 8:20 pm

Hi there,

I did a NAT session all day long sampling my Passive Tube EQ as I am digging into NAT at the moment. After having a look into VST Analyzer and how to see how my sampling is going I have seen some strange 'Artefacts' in the Plot on certain frequencies and certain levels.

See screenshot:
Artefakt.png
Does someone have any idea what this could be? Reaction of the tubes? Or is my Tube EQ possibly damaged?

Cheers,
Rob

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Re: Strange Plot with sampled signal

Post by mathias » Sat Nov 05, 2016 9:36 pm

vst analyzer has a FullScale (0 dBFS) testsignal.

try reducing the input and check again. if it goes away, it is the "overdriven" harmonics i guess.
system 1: windows 8 32 bit - samplitude prox/x3, tracktion6/7, reaper
system 2: mac osx yosemite - reaper(32+64bit), tracktion6/7(32+64bit)

both systems on: macbook pro (late 2009), core 2 duo 3,06 ghz, 4 gb ram, graphic: nvidia geforce 9600M GT 512 MB

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Re: Strange Plot with sampled signal

Post by robschroeder » Sun Nov 06, 2016 10:23 am

With the ASIOVST host I found a way to connect my Hardware with VST Analyzer (which is amazing) but I didn't find the 0dBFS Testsignal in VST Analyzer.

All I can see under VST Plugins - Generator is Silence, White Noise and Pink Noise. Any hint?

Thanks!

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Re: Strange Plot with sampled signal

Post by mathias » Sun Nov 06, 2016 3:24 pm

when you do a frequency or harmonics measurement, the testsignal is by default full scale.

you get options for the testsignals of all the possible measurements in vstanalyzer, with keyboard-shortcuts.
for example: frequency measurement is ctrl+F,
ctr+shift+F will give you the settings-window for that.

BUT BEWARE: changing the level from 0 dB in that setting window gave me unexpected and wrong results! change things with great care and always remember what was changed (all changes stay until you revert them).
otherwise you could run i to trouble ... ;)

vstanalyzer is a great tool, but there may be a lot of bugs under hood of this freebie, that were never catched and fixed.
system 1: windows 8 32 bit - samplitude prox/x3, tracktion6/7, reaper
system 2: mac osx yosemite - reaper(32+64bit), tracktion6/7(32+64bit)

both systems on: macbook pro (late 2009), core 2 duo 3,06 ghz, 4 gb ram, graphic: nvidia geforce 9600M GT 512 MB

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Re: Strange Plot with sampled signal

Post by robschroeder » Sun Nov 06, 2016 4:30 pm

mathias wrote:when you do a frequency or harmonics measurement, the testsignal is by default full scale.
Ah ok! Then I am doing everything right here :D
mathias wrote:vstanalyzer is a great tool, but there may be a lot of bugs under hood of this freebie, that were never catched and fixed.
Yes I am aware of this. But also happy to have a free tool such VST Analyzer (and I don't know any alternative yet).

As I am completely new to Nebula and NAT I take this tool more for studying and learning but never rely on graphs only and in most cases I trust my ears (which are not the best, but ok).

So thank you so much for your helpful input!

Cheers,
Rob

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Re: Strange Plot with sampled signal

Post by Support » Thu Nov 10, 2016 7:42 pm

Open NAT recorded file in an audio editor for inspection.
Best regards,
Enrique Silveti.
Acustica Audio customer and technical support
http://www.acustica-audio.com

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