Input Voltage/Gain Calibration for Guitar Plugins

[aciddose]

"How can a company that prides itself having "hyper-realistic" simulation can actually instruct this?"

The problem is simply your amazing naivete.

[aciddose]

Yet again, if you apply this Amplitube method you will have a Telecaster that is equally as hot as an EMG guitar.

What makes you think this? There is some failure of rationale here as it seems you haven't even considered the meaning of the words you're using.

If you adjust the input to handle the peak level of devices A,B, where you use the lower peak device it will produce a lower peak relative to the maximum peak device. This is obvious!

It doesn't matter as you've said yourself what the level is at the input as it can be adjusted losslessly ITB. The only criteria are therefore: 1) headroom 2) SNR 3) THD.

In fact you can improve upon SNR by applying non-linear processing (logarithmic, AKA compressor) at the input to the analog signal and applying the inverse ITB. This also eliminates most concerns regarding headroom.

Once you have the ideal input configuration you can set up the input gain ITB at any level you like. I can almost guarantee it will never be 0 dB and that it will almost always be between -20 to -6 dB for reasons of practicality. I can also guarantee it will differ between plug-ins as well as in some cases between multiple configurations of the same plug-in.

[Ilya-v]

What makes you think this? There is some failure of rationale here as it seems you haven't even considered the meaning of the words you're using.

Adjusting the gain of the preamp for different microphones (for diversity) will make them roughly the same recording volume in the DAW or mixer even if the microphones have radically different sensitivity specs and frequency response.
That also directly applies to guitars.
I have no idea why you are confused about such a simple thing, this is the first thing you learn about preamps/mixers.

I don't see any failure of rational, the hardware and software respond exactly in accordance to thorough understanding of them.
What I do fail to understand is why all your comments are "against the stream" even if they are about the most basic things that already well understood and agreed by both parties.

To preserve this difference in voltage between guitars, we should NOT adjust the gain pot individually for each guitar as suggested by the manuals, but rather keep it at one position for all guitars.
I actually want my guitars to have different voltage values, just like in the real world...

If you adjust the input to handle the peak level of devices A,B, where you use the lower peak device it will produce a lower peak relative to the maximum peak device. This is obvious!

It's obviously obvious, and this is exactly what we want as I already mentioned in the previous sentence.
If we don't change the gain pot on the audio interface, different guitars will have different peak values, as we want.

Seems you don't read my posts attentively, just rush to reply for the sake of arguing.
Can you actually contribute something useful to this thread, besides nay-saying?

It doesn't matter as you've said yourself what the level is at the input as it can be adjusted losslessly ITB.
Once you have the ideal input configuration you can set up the input gain ITB at any level you like.
The only criteria are therefore: 1) headroom 2) SNR 3) THD.

The point is not to re-adjust the level ITB per guitar, the goal is to calibrate once to a reference voltage and be able to change guitars without touching the gain pot on the AI or the the boost in the audio strip in DAW, just like in the real world with a real amplifier...
Can you grasp that concept? It seems I repeat myself over and over.

In my experience, the gain pot on the audio interface raises the noise floor with the gain, so the highest SNR is when the gain is at minimum.
Boosting in DAW will of course raise the noise floor of the input, but so does the gain pot on the AI.

Yes, I am well aware about noise reduction methods like non-linear digital bit arrangement (telephone) or frequency pre/de-emphasis (Vinyl, Cassette, early CD, AxeFx).
But I don't think consumer audio interfaces uses them.

[jacotzen]

When searching more on this topic on gearslutz, I found this

[Ilya-v]

It's well known that DAWs and Plugins work in floating point hence have infinite headroom.
You can easily go over 0.0dbFS on the audio track without clipping or at the Plugin input, it's the master track we should have an eye on.

If I relate this to the topic, 1V Peak at the interface input should reach 0.0dbFS for guitar plugins, but the interface input has more headroom hence may go over 0.0dbFS on the audio track without actually clipping.
This is exactly what the Plugin does with its "Input Level" knob, but we do it before the plugin because the DAW has better meters.

[jacotzen]

In this test, with the same settings as yesterday: first lick (gain knob at minimum on the input interface and +6.8db inside the daw) second lick (knob at noon on the input interface just before clipping when riffing, obviously when soloing this parameter is way below, no added gain inside the daw)

https://www.dropbox.com/s/ylz2t23ohf8xc ... 2.mp3?dl=0

this freaks me out... you have the 'distortion' but how the signal is managed, it is anything close to the real life and it is pretty clear if you pay attention at the sustain

[Ilya-v]

If you look at THIS post again, for your interface (+9dBu) you should boost by 9.8db in your DAW.

...but how the signal is managed, it is anything close to the real life

Good question.
If the amp simulation is accurate and our calculation of 1V input is correct, the simulated amp should behave like the real amp.
AxeFx II does this remarkably well, I don't see a why a VST shouldn't do the same with proper input voltage.

Amplitube is actually very accurate in terms of simulating the electronics of the amplifiers, that's why many respectable companies let them simulate their amplifiers, like Fender, Mesa, Marshall, Orange, etc..
But yet again, they ignore the fact that the input gain has a huge impact on how the simulated amp sounds.

[jacotzen]

EDIT:

Actually the settings I used are directly from the mixing engineer of this album as reported on gearslutz by himself, plus I use the same guitar, I don't care if it sounds identical freq per freq, I care how this sound respond to my fingers first. When reading gain staging threads on hi-gain amps, people, generally, test those sims with new metal riffing (rarely some solos!) that implies some power chords or single note muted, that's all, so in this scenario everything is somehow more manageable. Simulating hard rock guitars, like Van Halen for example, is another world and this is where you can clearly hear all the problems.

EDIT: forget about it: I copied the settings from another one who claimed to have copied them but actually they are not accurate, I will try again later, sorry.

[jacotzen]

https://www.dropbox.com/s/36acatpebpkjm ... 3.mp3?dl=0

Here it is, now the settings are identical at this https://www.gearslutz.com/board/attachm ... img024.jpg

Now, we might argue if the tone is identical but that's not the topic; despite the fact that the tone is pleasing I added one E power chord and a small lick to hear what's going on with the sustain: on single notes placed on the upper fretboard they dead instantly and that's relating to the gain staging I think. As usual the first example is with your settings (+9.8db this time) and the second is with the knob at noon on the interface. All meters are at good level on green, nice and clean BUT something is still wrong! I don't know if a DI could solve the problem or what.

[Ilya-v]

.3

[aciddose]

I'm not sure why you'd "read between the lines" and interpret things I've never said.

Did I once say "individually normalize input levels for each device" ?

As far as I know nobody tried it yet with desktop audio interfaces.

Perhaps none of you have but us engineers are well aware. In fact I explained this process to you in this thread.

[jacotzen]

Aciddose, I'm not an engineer for sure, think about... just discovered the difference between db and dbfs not long time ago

Question: why in your opinion, if you listen to my last mp3, despite your settings too (peaking at -3dbfs with maximum gain from the interface), my sound dies shortly when I play the upper notes? (nothing wrong with my guitar, a real amp reacts in a different way)

[aciddose]

What do you mean "sound dies shortly" ? This could mean almost anything and I'd need to be familiar with the hardware and software you're using. It would be both a waste of time for myself as well as for you since anything I could say would be pure speculation.

While working with this stuff the primary goal should be minimizing noise levels. Once you have the signal ITB you can do whatever you want from that point.

I just found the advice to worry about measuring signal levels quite ridiculous because not only was the rationale flawed and completely disconnected from the action taken, the action taken would have worked to produce nearly the worst possible result.

If you want to worry about sending a signal to your plug-ins which matches what the developer used, you need to follow the instructions the developer provided. If they did not provide instructions you're out of luck!

To assume that any reference level would produce better results is extremely naive. To assume the reference would be 0 dB is worse than just naive, it's just simply stupid.

Part of the naivete I mentioned is in the assumption that these "highly accurate models" are anything even close to that. They're plugins!

If you want to try finding two pieces of hardware and getting them to sound the same you'll begin to realize how foolish it is to give advice on how to operate software other than that repeated verbatim out of the documentation.

If you want proper instructions you'll need to ask the developers, programmers and engineers who design this equipment whether hardware or software.

[Ilya-v]

Removed, Not important

[izonin]

You're putting too much thought/energy into this. If you're not happy with the noise floor of your interface, just invest in a higher quality one. Pro's rely on Apogee and Mytek converters for a reason.