Moderator, CNF Help Please

[Malcolm]

Mr. Maier et al: Your software is absolutely fascinating and highly impressive, but I need some technical explanations to understand what the CNF dialog box represents to shorten my trial and error work on mid-fifties 78s.
What does a blue dot represent? A peak or valley on a band pass or notch curve? An FFT calculation point?
What effect does horizontal movement of blue dots achieve?
Any value in pulling one blue dot below another i.e., stacking at a lower setting?
What is more effective at removing broadband noise without introducing artifacts, higher threshold setting with lower attenuation, or very low threshold with higher attenuation?
Why are the introduced artifacts ?swirley,? or like the intermittent long hiss of an out-of-centre disc?
How do you reduce the ?hollowness? sometimes introduced?
Are blue dot adjustments most useful in the upper end of the recorded spectrum?
The noise at the beginning of the recording is higher than the end of the recording and the result after application of the CNF is a residual "hard noise sound" that is non-uniform in nature and almost appears to be as stated earlier to be generated by an eccentric disc, although observance of the tracking does not indicate such. Should some residual noise be left to be removed by the Medium or other filter? Is there any value in a second application of CNF with another re-sampling -- it seemed to me to be slightly improved, but I expect at some deterioration of the original content. Just how much essential content can be heard in "keep residue"-- how intelligible should it be?

Thanks in advance,
Malcolm

[Craig Maier]

Re: Moderator, CNF Help Please

Here are the answers to your questions in order. (BTW - some of these questions are answered in the users guide.)

What does a blue dot represent? It sets a point through which a line is drawn to the next inflection point. That line establishes the threshold value above which signals are passed through the system between two inflection points.

A peak or valley, etc? It represents the threshold of the feed through signals for the reverse fft.

Horizontal movement of dot? This affects the frequency of the blue inflection point.

Stacking points? Not a useful move since the lower one will take precidence.

Most effective without introducing artifacts? Lower attenuation values produce less artifacts, but also less noise reduction.

Why the swirleys? This artifact is produced by un-even noise distributions associated with the source and settings that are too agressive.

How to reduce hollowness? Go less agressive with the settings. Do not try to achieve a no noise situation, but a balance between reduced noise and pleasing sound.

Are blue dot adjustments most useful in upper end of the spectrum? I adjust the upper ones to get the best hiss reduction, and I adjust the lower ones to get the best rumble reduction without destroying the bottom end.

Noise at beginning vs noise at end. The Continious Noise filter can be applied selectively on a wavefile. If the noise is much different at the end compared to the beginning, use the selective process which is described in the users guide (it is a general process that can be used in conjunction with any filter.)

Keep residue mode intelligibility? This should not be intelligible. If it is, then you are removing much to much from the wavefile. You want to adjust the system so that keep residue contains mostly noise, with little signal.

I hope that this help clarify some things regarding the CNF.

[Malcolm]

Re: Moderator, CNF Help Please

Craig, your explanation regarding CNF operation has been extremely helpful to me and I sincerely appreciate your taking the time for such a detailed response.
malcolm