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When sampling in offline mode

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When sampling in offline mode

Postby Definity » Thu Dec 22, 2011 10:46 pm

How hard should I be hitting the master buss in my DAW? -18dB -12dB or should I go up to -0.1dB? I have been trying 0.1 and getting some strange results. I'm trying to sample 3 nebula pre-amps in 1 program, would I need to make sure I go into each instance of nebula at -18dB?
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Re: When sampling in offline mode

Postby Henry Olonga » Mon Jan 02, 2012 8:37 pm

Seeing as no-one else has given this a go - :D in my experience it is good to have some headroom for each plugin being sampled and also the Master buss. Add each plugin and as you do make sure the highest signal does not clip or give you the spikes that hitting nebula hard gives. This IMHO is where trouble starts way before the master bus. If even one instance of Nebula goes over the internal limits then you will get wrong deconvolve results. You want to be just under that threshold so that you are sampling the highest kernel possible without the artifacts that going above it gives. You know the huge spike of low freq energy. So you will need to play with nebula's input and output sliders. Then add the next plugin and again make sure the gainstaging is right again etc

You could do well to leave perhaps some headroom per plugin is my suggestion. You can use your trim going into the master bus and then use the gain of your master plugins to deal with appropriate gain staging if it is too hot going into the master. The master bus can handle less headroom. For example if you have a saturation plugin that has soft clipping ( for example - Antares warm ) which is what you may wish to sample but make sure you do not go over the full scale digital signal as you well know.

YMMV
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Re: When sampling in offline mode

Postby giancarlo » Tue Jan 03, 2012 10:54 pm

h-man wrote:Seeing as no-one else has given this a go - :D in my experience it is good to have some headroom for each plugin being sampled and also the Master buss. Add each plugin and as you do make sure the highest signal does not clip or give you the spikes that hitting nebula hard gives. This IMHO is where trouble starts way before the master bus. If even one instance of Nebula goes over the internal limits then you will get wrong deconvolve results. You want to be just under that threshold so that you are sampling the highest kernel possible without the artifacts that going above it gives. You know the huge spike of low freq energy. So you will need to play with nebula's input and output sliders. Then add the next plugin and again make sure the gainstaging is right again etc

You could do well to leave perhaps some headroom per plugin is my suggestion. You can use your trim going into the master bus and then use the gain of your master plugins to deal with appropriate gain staging if it is too hot going into the master. The master bus can handle less headroom. For example if you have a saturation plugin that has soft clipping ( for example - Antares warm ) which is what you may wish to sample but make sure you do not go over the full scale digital signal as you well know.

YMMV

good suggestion
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Re: When sampling in offline mode

Postby voidar » Fri Mar 23, 2012 3:37 pm

I am not sure how helpfull that was really.

Say you open up an offline preamp session in NAT and generate the sweep. NAT spits out this full digital scale file.

If I sample making sure the peaks return no higher than -18dB full-scale, the program will turn out too quiet.

How can I have NAT work at a different level?
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Re: When sampling in offline mode

Postby enriquesilveti » Sat Mar 24, 2012 12:28 pm

-18 dBFS is a nominal RMS value for get EBU r-68 norm. Peak should be between -1 dBFS and -18 dBFS. That means you are working with 17 dB dynamic range audio program. Check if your analog gear and your AD/DA are calibrated to work with those values. So the #19 VTT (due the first VTT should be a -1 dBFS) should have the -18 dBFS value and hit the 0 VU value in the analog gear. Check also the analog gear send 0 VU to the output when internal parameters are in the nominal value if not you should add or remove gain in other to get the same value in the output, that is called pseudo normalization, in Nebula world is GDRIVE parameter.

Please remember that a pure sine has a 3 dB of dynamic range so the difference from RMS to Peak value in a VTT and/or pure sine is a 3 dB or 0 dB if your add +3 dB in RMS value, AES17 norm.
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Re: When sampling in offline mode

Postby voidar » Sat Mar 24, 2012 6:56 pm

So what you are saying is the last frequency swipe should hit your converters at 0VU (-18) max from the analog device?

I use the Klanghelm VU plugin.

What I have done is set it to 0dBfs on the return and have the needle not go above 0 (but close) on the first swipe.

After the deconvolve I edit the global level output because the program always turns out quieter than bypass.

This seems to sound correct.
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