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How to clone an impulse response?

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How to clone an impulse response?

Postby vicnestE » Thu Nov 24, 2011 9:43 am

Hi.

I've tried to clone a DRC impulse response into nebula.


It's a 44.1KHz 65535 samples wave file.
I used NAT3 with the 3 seconds offline reverb NAT template to clone the IR.
The backupthis.wav is processed in Reaper 4 64bit with Sir2 64bit. No clipping in the chain and resulting wave. And I deconvlved the processed signal into a nebula program.


The sound is different and the sampled nebula program is tilted to high frequency a bit. As shown in attachment, the frequqncy charts are aligned at the low frequency peak point.


I want to clone the IR precisely at least in frequency domain and compare them fairly. The nebula one sounds more clear and open but the frequency curve is not exactly the same.


Any idea what should I do to clone an impulse response?
Attachments
Nebula Reverb.png
Nebula Reverb Curve
Nebula Reverb.png (203.76 KiB) Viewed 1868 times
SIR2 IR Loader.png
SIR2 IR curve
SIR2 IR Loader.png (222.99 KiB) Viewed 1868 times
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Re: How to clone an impulse response?

Postby yr » Thu Nov 24, 2011 12:33 pm

I've tried it many times last month, because I wanted to create a "quasi modulating" Bricasti preset (using multiple IR's). The results always sound different from the source (less depth and often more metallic/brighter) and generate crackles/noises. You can hear it by running the Volterra test tone though your reverb preset. The noises seem to be a limitation of the playback engine.
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Re: How to clone an impulse response?

Postby giancarlo » Thu Nov 24, 2011 5:31 pm

I don't remember which template you should use for reverbs in offline mode. Trouble is that nebula tries to synchronize the main peak, so the beginning of your sample is maybe truncated, here the difference.
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Re: How to clone an impulse response?

Postby enriquesilveti » Thu Nov 24, 2011 5:47 pm

NAT > Sampler > Offline > Sync
1. Un check Sync
2. Click on Generate
After get your processed files, Deconvolve.
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Re: How to clone an impulse response?

Postby yr » Thu Nov 24, 2011 7:35 pm

The sync is un-checked as default in the clean reverb templates (v10)

enriquesilveti wrote:NAT > Sampler > Offline > Sync
1. Un check Sync
2. Click on Generate
After get your processed files, Deconvolve.
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Re: How to clone an impulse response?

Postby vicnestE » Thu Nov 24, 2011 8:33 pm

Same here. In the default "Clean Reverb (3 sec) - OFFLINE.xml", "Sync" is not checked.

Is there a way to set the program so that nebula won't synchronize the main peak?

Or it's the nature of nebula processing?

The DRC signal is measured and calculated by an elder audio pro friend, when I told him the nebula one sounds better and less aritificial. He wanted to know more about nebula.

But once I analyzed the signal, the less than precise result is lack of convincing. Hope there's a way to duplicate the IR.
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Re: How to clone an impulse response?

Postby giancarlo » Fri Nov 25, 2011 10:14 pm

check classic/enhanced convolution
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Re: How to clone an impulse response?

Postby vicnestE » Sat Nov 26, 2011 10:29 am

Using 5sec clean reverb with classic/enhanced convolution.

The difference is smaller but visible.

IR one is the brighter pink, nebula one is the skin color. The difference in 50-250Hz is most obvious.

I shall try longer sweeping time later.
Thank you, G!
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Left Channel small differences.png
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Re: How to clone an impulse response?

Postby vicnestE » Sat Nov 26, 2011 11:30 am

Same problem even with 8sec offline reverb.


I uploaded the IR so someone with more experienced hands might try to clone it using customed NAT3 template.
Attachments
Ken's DRC 20111122 stereo version.wav
(479.96 KiB) Downloaded 95 times
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Re: How to clone an impulse response?

Postby giancarlo » Mon Nov 28, 2011 7:15 am

while nat is able to clone an impulse response perfectly, nebula sometimes can't play the correct predelay. It happens for digital linear eq emulations and sometimes digital reverbs, but you get back phase coherence. They are just few cases. A library dveloper could deactivate synchronization, but it's complicated. So if it can't be cloned, go ahead
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