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New AHD feature and Micro Kernels in NAT

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New AHD feature and Micro Kernels in NAT

Postby Unicorn » Fri Jul 01, 2011 8:27 am

Hello,
in the latest version of NAT there is the possibillity to use Micro Kernels and AHD and I have some questions.

When I select micro kernels is this mode in Nebula playback always selected? Or is it possible to switch them on and off in Nebula? What is the difference in quality?

AHD- Does it mean anti harmonic distortion?
It is centered at 1000 Hz. Does that mean it will work only at 1000 Hz or up at 1000 Hz?
What changes when I turn it lower or higher.

I hope all the questions are understandable and I can get an answer soon. :)
Thanks in advance,

Markus
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Re: New AHD feature and Micro Kernels in NAT

Postby giancarlo » Sat Jul 02, 2011 7:40 am

actually ahd is still in beta. It features a way for improving harmonic distortion precision and a destructive way for getting shorter kernels, so two different things. Sometimes there are issue on dynamic modes, something turns out good and something not due to nebula dynamc interpolation. We'll release a fix
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Re: New AHD feature and Micro Kernels in NAT

Postby Unicorn » Tue Jul 05, 2011 2:52 pm

Thanks for your answer.
I have some more questions because at the moment I am finetuning a NAT session to get the best out of sampled guitar cabinet.

How does the dynamic interpolation work in general?
As I understand it with the "IN" in Nebula and the loudness of the music signal itself you can place the audiosignal in the sampled ranges.
Lets say I sample with 5 dynamic steps where each has 2 dB difference. The loudest sweep generated in NAT3 is around 0 dB, the lowest then at -10 dB.
How loud would the music signal have to be in the DAW to reach the loudest sampling step? (Given that the IN and OUT in Nebula are centered)

We're using Template_dynamic_1h (10K) as basis.
Last edited by Unicorn on Tue Jul 05, 2011 5:29 pm, edited 1 time in total.
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Re: New AHD feature and Micro Kernels in NAT

Postby Ermz » Tue Jul 05, 2011 5:23 pm

What we are attempting to do is get as authentic a representation of the cab exertion and 'air pushing' as possible. So we want to make sure that any guitar preamp signal going into the Nebula Cab Program is hitting the optimal gain range, for its loudest peaks to be triggering the 'loudest' state of the sampled cab, and for all signal content below that for it to constantly be dynamically switching between cab loudness stages, to get around the 'stuck' and 'ringy' effect that normal, static impulses have when modeling cabs.

At the moment we are unsure which templates/options are best in NAT to achieve what we are after, nor do we know how to measure what gain range is ideal to be hitting the programs with our signals.

Any help on that front would be greatly appreciated!

PS. Here are our results as they currently stand. A real cab was mic'ed, and both impulses and Nebula programs were created of that set-up, and tested side by side with identical input signals. As you can hear, the Nebula is very close, but still has the hollow, phasey element that pervades convolution based cab sims. We are hoping to make this less noticeable, or inaudible entirely if possible in order to render using the real cab obsolete.

http://dl.dropbox.com/u/285689/Impulse% ... mpulse.mp3

http://dl.dropbox.com/u/285689/Impulse% ... Nebula.mp3

http://dl.dropbox.com/u/285689/Impulse% ... %20Cab.mp3

Note: All tones are raw off the amp, with a 60Hz HPF.
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Re: New AHD feature and Micro Kernels in NAT

Postby Ermz » Sat Jul 09, 2011 4:41 pm

Any chance to get a response?

We are still working at this, but it would remove so much of the guesswork if we could get pointed in the right direction by a developer.

Thanks!
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Re: New AHD feature and Micro Kernels in NAT

Postby giancarlo » Sat Jul 09, 2011 7:01 pm

I think you should test sessions quickly, than choose the best one for sampling. Without a graph of the original gear I can't guess much. Ahd is great, but still in betatesting, and you can't use many harmonics if your preset is dynamic, we'll improve it asap
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Re: New AHD feature and Micro Kernels in NAT

Postby Ermz » Mon Jul 11, 2011 12:57 pm

We respect that you're working on AHD at the moment, that's great. Can't wait for the feature to become fully ready!

The more immediate concern for us is how to figure out the gain range of our programs.

Much as Alex B has aligned -18dBFS to be his '0VU' point on his console programs, we need to know what levels into the Nebula Cab Programs correspond to what loudness levels of the power amp/cabinet in real life.

Is there a way to define this when sampling the programs using NAT? Or does it just relate to the levels used when doing the sampling procedure? Or something else I'm missing?

Thank you!

PS. What sort of graph would you need of the original gear? Is there no template which corresponds best to modeling power amps/cabinets in general? Just a best approximate starting point.
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Re: New AHD feature and Micro Kernels in NAT

Postby giancarlo » Mon Jul 11, 2011 6:45 pm

the reference is the maximum headroom you reserve for your session, es for -18db your louder tone named 0db should be mapped to +18db input gain in your gear. About graphs I mean harmonic distortion and possibly frequency response. If I'm not wrong both vstanalyzer and nat are good for getting them
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Re: New AHD feature and Micro Kernels in NAT

Postby Unicorn » Sun Jul 24, 2011 6:39 pm

Hi,
I will gladly post the graphics.

harmonic_ji.jpg
harmonic_ji.jpg (209.39 KiB) Viewed 2177 times


fr_ji.jpg
fr_ji.jpg (209.78 KiB) Viewed 2177 times



Could you please elaborate on your last post.
You said the louder tone should be mapped to +18 dB input gain in my gear. Since I am working in the digital domain there is no +18 dB for me.
In NAT there is a Gain that I can adjust. Is that what are you talking about?
But I thought this Gain is just for finding the right level or rather setting the output level of the sweep.
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Re: New AHD feature and Micro Kernels in NAT

Postby enriquesilveti » Sun Jul 24, 2011 9:16 pm

You said the louder tone should be mapped to +18 dB input gain in my gear. Since I am working in the digital domain there is no +18 dB for me.
In NAT there is a Gain that I can adjust. Is that what are you talking about?
But I thought this Gain is just for finding the right level or rather setting the output level of the sweep.


-0.00 dBFSD is distortion in digital. If you are full in digital you can map -0.00 dBFSD to -1.00 dBFSD and after deconvolve you add a +1.00 dBFSD of pad in Nebula.

The same you should do in analog takeing about 1 dB of headroom using gain in NAT.
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