[FEATURE REQUEST] Add more saturation parameters

[SamuelMiller]

Please consider adding more parameters to control the saturation profile. Analyzing the Chow Plugin with plugin doctor, I see that just odd harmonics are being generated, besides the hysteresis STN which seems to generate some very low db even harmonics, which I am not sure are audible. In some, tape emulation plugins such as Softube Tape, the "Tape B" setting generate both even and odd, non-linear low and high-ordered harmonics (https://mixmasterforum.com/t/softube-tape-plug-in-analysis/1334). Although the current GUI is already pretty compact with features, and it may be beyond the scope or goal of this plugin, please consider adding more saturation parameters to control both even and odd harmonics, similar to the excellent free plugin GSatPlus by TBProAudio, which offers saturation settings such as Character, Stages, Fluctuation, Even and Odd. For example, An additional panel called "Sat" could be added to the "Tape/Comp/Tone" section that offers similar parameters (Stages, Fluctuation, Even and Odd), perhaps eliminating the "Character" parameter since the "Hysteresis" settings already seem to serve a similar function. This would allow the user to custom create their own Tape machine emulation with tube characteristics for example, or minimize the need to add another saturation plugin in series to supplement with more even harmonics to get a warmer, tubey sound.

[jatinchowdhury18]

Thanks for the feature request! I had a couple of thoughts:

First, doing "static" harmonic analysis with a sine wave (which I believe is what Plugin Doctor is doing) is not necessarily an accurate way to evaluate the nonlinear characteristics of the plugin. The hysteresis process implemented in the plugin is both time-dependent and input-dependent, meaning that the harmonic characteristic will change with the input.

With that in mind, I'm hesitant to alter the hysteresis implementation, partly because it's quite compilcated under the hood, but also because I wouldn't want to sacrifice the dynamic nature of the nonlinear process in favor of having more control over a more static harmonic process.

Also, I'm quite hesitant to add more parameters at this point. As you mentioned, the GUI is already pretty packed with parameters, to the point that even I sometimes feel overwhelmed by all of the choices.

Finally, I think for users wanting the more tube-like sound that you described, I think adding another plugin might be the better option anyway, since it would give the user more specific control over that part of the sound anyway.

Anyway, more specific control of nonlinear harmonic structure is definitely something I'm thinking about for future plugins, but at the moment I don't plan to implement that sort of thing in ChowTape.

Thanks,
Jatin

[SamuelMiller]

I didn't realize that the hysteresis process was time-dependent and input-dependent, Cool. The Hammerstein analysis in Plug Doctor gives the frequency response of generated harmonics from 20hz up to the Nyquist (e.g., 22khz). From the manual, "this tab provides a more detailed look at the nonlinear behaviour of a plugin or a piece of hardware. Briefly speaking, the Hammerstein model tries to fit the system under investigation with a power series, with each component of the series multiplied by its own linear filter. You can select the order of the power series, with a maximum of 7 allowed. That way you can see not only how much a certain higher harmonic (say, x^3) is contributing to the signal, but also how its response is different across different frequencies. Technically, the Hammerstein model consists of the diagonal terms of the corresponding Volterra kernel."

In case you are interested, below is an example of a Plugin Doctor Hammerstein analysis of the STN hysteresis setting in Chow Tape, with a fundamental at -3db, 7 order harmonics selected.

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