Nova GE, LP filter, 21-22kHz artifacts?

[Traverser]

Hi,

I observed that using the LP filter in Nova GE some kind of remnants or artifacts appears at 21-22kHz with the following quality modes:

- insane
- precise+
- insane+

BUT NOT with:
- precise

See the attached screenshots.

The same can be observed in surgical mode, and with any db/oct slope.

And I would like to ask if this is the intended proper behavior, or is this a bug in “precise” mode or bug in “insane, precise+, insane+” modes?

Thank you in advance for your kind help in this.

[cantaloupe]

I can't replicate this in any of the modes, for what it is worth.
No artifacts.
In both 96k and 44.1k.

[Traverser]

I used sample rate 44.1kHz.
Nova GE, v2.1.5, Jul 27 2021, 03:30:35
Format: VST2 64bit, Windows 10.

Test tone: pink noise.

Did you increased the “Freq HI” in SPAN above 24kHz?
You should be able to see that thin red vertical line at the end of the usable frequency range.
If not: you are not configured SPAN to show this artifact.

[Traverser]

DAW: Reaper v6.43/win64

[Traverser]

And not just SPAN can show this, even a new instance of Nova GE show this, but not the one which introduces it. See the attached screenshots.

[cantaloupe]

Did you increased the “Freq HI” in SPAN above 24kHz?

Yes.

[Kr3eM]

96 kHz
Nova GE, v2.1.4
VST2 & VST3 64bit, Windows 7

Test tone: pink noise

I see the same...even tried an older version 2.1.2 and got the same result.

[cantaloupe]

Sorry, i must have done something wrong last time. I tried it again and now it happens here as well. Nova GE 2.1.5, VST3

[Traverser]

Kr3eM & cantaloupe thank you for checking the reproducibility of this issue.
Hopefully FabienTDR will also see this topic/issue and will tell his thoughts on this.

[cantaloupe]

FabienTDR will also see this topic/issue and will tell his thoughts on this.

For sure. Or you could file a bug report directly: https://www.tokyodawn.net/fill-a-bug-report/

I have done that with a Nova bug previously, and they were very quick to fix the issue. TDR always had great customer service.

[Traverser]

FabienTDR will also see this topic/issue and will tell his thoughts on this.

For sure. Or you could file a bug report directly: https://www.tokyodawn.net/fill-a-bug-report/

I have done that with a Nova bug previously, and they were very quick to fix the issue. TDR always had great customer service.

I already filed a bug report after I posted the issue here. I received no answer yet. I hope it went through their system.

[FabienTDR]

This is not an issue, it's how Chebychev filters look. We use these for steep filter modes, simply because they sound better.

[Traverser]

And why is that the NovaGE's own analyzer does not show this artifact, just another instance after it?

[FabienTDR]

That's because the stop band ripple of the Chebychev sits below the analyzer's range. Nova's analyzer only goes down to -48dB or -96dB. The Chebychev "wobbles" start right below ~100dB.

[Traverser]

Then why is that a second NovaGE placed after the one which introduces this artifact can show this artifact?

If I understand what you said, the second placed after the first should not show it also. Or?