Thanks, guys! In that case, I'll keep thinking out loud...
Alas, I'm woefully under-read on the advances in viol-family acoustics. So I haven't come across Dr. Hutchins' work yet. I've got enough physics of acoustics theory in my head to get by, from years of doing live sound and tuning rooms and so forth, coupled with a certain amount of basic electronic and mechanical engineering chops. So I can read Siminoff's stuff on tuning the air chamber on a mandolin, and can sorta follow Doc Kasha's stuff with Richard Schneider on structural impedence and boundary effects, but still get lost in the more academic approaches.
As to using the SF-2 to mimic plate resonance peaks, well, yeah it can be done to a degree. The downside is that you have virtually zero ability to control the phase response of the filter, other than by being aware of the basics of a state variable filter.
(The high-pass and band-pass outputs are 180 degrees out of phase to each other, and each is 90 degrees out from ther bandpass output. Then they're summed for the combined output and, often, mixed wet/dry with the original signal which may or may not be 180 degrees out of phase with the bandpass pole.)
And, even being able to discern the phase/amplitude response relationship in the SF-2, you have no way of measuring (or simulating) the same relationships in an instrument or environment you're trying to model.
Ultimately, what the response peaks represent is a combination of the actual generated tone comb-filtered through the plate and cavity amplitude and phase resonances of the environment.
All of which is why DSP processing of audio signals--with the intent of simulating various amps, cabinets, instruments, etc.--has been so difficult until recently. These days, the approach is to make reference recordings of the source item, then use advanced DSP techniques to discover the phase and amplitude structure. Then use that as a baseline with which to adapt the model's signal attributes to match.
Fortunately, the human ear is a much more sensitive measurement instrument than it's given credit for, and with some practice, it's quite possible to get close enough in modeling to achieve satisfactory results. The big hurdle in learning how to do that kind of aural modeling, though, is to gain an understanding of how phase changes affect what you hear. One easy way to do that is to run one channel of a stereo through a phase shifter pedal that's had the sweep function disabled. Listen, then change the phase shift and keep listening. Change it again. You'll get to the point where you recognize the characteristic sounds of a pair of tones at an identical pitch, but with varying degrees of phase delay between them.
Once you can recognize the type of sound of a phase differential, you'll be able to hear it buried in the complex signals you're working with with the SF-2. So you'll have a better idea of what to push or pull, frequency and amplitude-wise, to get closer to the tone and timbre you want to mimic.
It gets back to one of the things Mike Tobias showed me: he had tuned a solid-body bass to D. He could rap the upper horn and get a very clear tone. He could also rap the lower body, near the controls, and get the exact same tone. But when we put it up on the scope, we found that each zone was 90 degrees out of phase with each other. Rap the horn, and the body zone resonated in D, but 90 degrees forward-shifted. Rap the body, and the horn was 90 degrees behind.
Turns out that was pretty much the ideal, for that particular bass design. He had done one earlier where he managed to get the zones in phase, and of course the bass simply wolfed out at that resonance. He realized that where you plucked the string determined which zone has precedence, and so determined the real-time phase angle of the complex signal. It led him to some interesting experiments with pickup placement. Unfortunately, he didn't have any way of measuring the comb-filter effect the pups had in interaction with the string, at any given note. So it was back to tuning by ear, but with a better inate understanding of how a given change in design would change the tone.
