As I know Nebula Captures and apply both Frequency Response and harmonic distortion response simultaneously.
Today I have been thinking that a low end harmonic distortion produced by a hardware gear will cause overall frequency response shift,which I think is going to be seen as Low Frequency Boost by NAT. (I haven't work with NAT so I don't know how it works)
The gear will ADD harmonics to the input signal and leave the FREQ of audio untouched
So Wouldn't capturing and applying Both FREQ and THD separately make the the boost double, and the emulation inaccurate?
Or are NAT and Nebula intelligent enough to avoid these kind of issues? If Yes, would you tell me How?
In most every 3rd party library are both manuals and VST Analyzer graphs posted. In those graphs included detailed harmonic/THD/noise data.
Go to any of the Developer sites and download ... it's all free to see.
You can also grab the actual program VSTAnalyzer and view the details in real-time. This is very useful to see how an eq actually responds.
Also ... follow some of the discussion from the library developers themselves. Many of them share their own personal observations, and testing. You may then begin to appreciate the efforts they put into these libraries to create accurate models directly compared to the hardware that's been 'Nebula-tized'.
A thought to consider [if new to the analogue world ... particularly the much sought 'vintage' gear, may enlighten the difference between actual tubes, resistors, coils, values, caps, and transformers ... compared to mathematical formulas and algorithms.
What is the difference between a synthesizer making the sound of a violin as compared to the sound emanating from the actual instrument ? To some ... they are both violins
Presets within a library usually come with several variations, or kernels ... at its simplest, we'd have full harmonic content of the entire hardware unit, and then a 'clean' preset. This allows combinations that can be used to our sonic advantage.
An example technique may be a typical 4 band equalizer, where each individual band is set to a 'clean' preset ... and the combination run serial into a 'full kerneled' Pre-Amp preset [many times included in the library]. The combinations are user defined to customize/tailor the sound beyond the curves.
I like to test my plugins using VSTAnalyzer or Reaper w/SPAN, not to predict how they sound although I know what certain visual signatures sound like by now. But I like to use those tools to see how the controls act, interact and stuff like that. There are lots of diagrams and plots that many devs post and give me a clue about eq bandwidth and relative harmonics as RJ noted. Also Mr G hit the problem that I experienced early on with VSTAnalyzer, I was overloading Nebula and getting the wrong idea. For that reason I use a DDMF plugin so I can insert a FreeG (Sonalksis) plugin and set it to -18db rms max while using VST Analyzer. Otherwise I just place some calibration tones in Reaper and look at SPAN. Good luck!