Wideband dynamic compression bug, or misunderstanding TDR Nova

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macmelon
KVRer
5 posts since 28 Feb, 2020

Post Fri Feb 28, 2020 11:43 am

Hi, TDR Nova seems to me fantastic, but I came across something strange, maybe the error is on my side, I have tried many different scenarios, ratios, even with with noise, but here is an example of the issue.
I have generated a test signal, 5 sec intervals of 880 Hz Sine waves from -72dB to -1dB with 1 dB steps. I have compressed this signal with:
Wideband dynamic, 0 dB Gain, -30 dB Threshold, 10:1 ratio, fastest attack&release, no EQ Gain, no Out Gaing, 0% Dry.

What I expected from the math:
-40 dB -> -40 dB
-30 dB -> -30 dB (with a softer knee less)
-20 dB -> -29 dB (with softer knee slightly less)
-10 dB -> -28 dB
-5 dB -> -28,5 dB
-1 dB -> -28,9 dB

What I got:
-40 dB -> -40.04 dB
-30 dB -> -31.20 dB (OK, not hard knee)
-20 dB -> -23,87 dB (huge difference from the expected -29)
-10 dB -> -14,07 dB (seems almost linear from -20 dB)
-5 dB -> -9,07 dB
-4 dB -> -8,07 dB
-3 dB -> -7,07 dB
-2 dB -> -6,07 dB
-1 dB -> -5,07 dB (on the last few 1dB/1dB, not 10db/1db as the ratio would suggest)

So, this not a compressor? What am I missing?

Thanks in advance!

User avatar
Gamma-UT
KVRAF
5409 posts since 8 Jun, 2009 from UK

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Fri Feb 28, 2020 12:25 pm

> 880 Hz Sine

> fastest attack&release

I can’t help feeling this combination is the source of the problem.

macmelon
KVRer
5 posts since 28 Feb, 2020

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Fri Feb 28, 2020 12:31 pm

Any attack (eg. slowest/slowest, 50/200 ms) produce the same. (And eg. Dead Duck work as expected.)

heavymetalmixer
KVRian
575 posts since 8 Jan, 2017

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Fri Feb 28, 2020 3:46 pm

First: No compressor out there is perfect, not evne NOVA, and they all work differently.
Second: Not many people knows this, but NOVA uses RMS compression with a very small RMS window, it will let go very fast peaks.

macmelon
KVRer
5 posts since 28 Feb, 2020

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Sun Mar 01, 2020 8:45 am

I still don't get it: I have tried a -1 dB 40 Hz square wave, with the same 10:1 ratio, and it is -5,07 dB again. In RMS it is from circa +2 dB to circa -2 dB. And with 2:1 ratio is the same. What does the 10:1 ratio even mean?

My best bet is still a misunderstanding on my side, but please help me understand what it is!

macmelon
KVRer
5 posts since 28 Feb, 2020

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Sun Mar 01, 2020 12:28 pm

Maybe it is something like what we can see on the left, a range for the compression, but a surprisingly small range: https://www.junger-audio.com/uploads/im ... ressor.jpg

cron
KVRAF
3314 posts since 27 Dec, 2002 from North East England

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Sun Mar 01, 2020 12:59 pm

Nova's wideband is unusual in that it can still produce strongly frequency dependent behaviour. Are all bands other than the W-band actually disabled? Parts of the spectrum covered by active bands (even if they don't appear to be doing anything) won't be included in the W-band signal IIRC.

Nova's knee is ratio-dependent incidentally - higher ratio = harder knee.

heavymetalmixer
KVRian
575 posts since 8 Jan, 2017

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Sun Mar 01, 2020 1:02 pm

cron wrote:
Sun Mar 01, 2020 12:59 pm
Nova's wideband is unusual in that it can still produce strongly frequency dependent behaviour. Are all bands other than the W-band actually disabled? Parts of the spectrum covered by active bands (even if they don't appear to be doing anything) won't be included in the W-band signal IIRC.
This, and the fact that all bands (except the Wideband IIRC) have a 3 db per octave HPF in their side-chain, so they don't go absolutely crazy with low frequencies.

macmelon
KVRer
5 posts since 28 Feb, 2020

Re: Wideband dynamic compression bug, or misunderstanding TDR Nova

Post Mon Mar 02, 2020 3:59 am

Yes, I'm aware of the ratio dependent knee.
nova.png
I guess we can even see the -4,07 dB from the yellow line.
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