Help me understand compliance!

I think the difference between #5 and #6  is that #5 refers to a mismatch of a low compliance cart to a low mass arm and #6 refers to the mismatch of a high compliance cart to a high mass arm.

Either way... the big thing that is overlooked by everyone thus far is he drastically altered one of the factors (compliance) in the traditionally used formula and kept the other two constant.  His results did not show the expected shift in resonant frequency but did show a decided effect on the damping of the frequency peaks.  I believe his compliance calculator goes more to showing the possible magnitude of the unwanted behaviors resultant from a mismatch and I think situation #5 is problematic and #6 may be quite benign.

As you have heard,  I use a really high compliance cartridge in an insanely high mass tonearm with no apparent ill results.  Even though it breaks just about every matching rule known to man and incites endless lectures on my ignorance,  I have found it to be a sublimely musical combo.

Einstein one said...  “If the facts don't fit the theory, change the theory".  Sadly, in this case I don't see that ever happening.

@intactaudio , I can't be sure what you mean. What to you is an insanely high mass arm (in effective mass please)?  and what is a really high compliance cartridge? It sounds fine to you but, I would like to know what is happening where it does not sound, below 8 Hz. If the tonearm is massive enough some very unhappy things are going to manifest and no cartridge I know of (excluding the Decca) has enough damping to deal with it. Hook your phone stage up to an oscilloscope. 
As I said before, I do not use formula or rely on theory. I measure. Unless you measure one has no idea what is going on. "Sounds good" is a hopelessly inaccurate way of describing the situation where the needle hits the groove. T

This is for certain. If you add mass the resonance frequency is going to drop. If you remove mass the resonance frequency is going up. If you can't see or hear the resonance point with a good test record it is because the system is dampening it out. In which case it is not a problem. If you want to increase your resolution hook up an oscilloscope to your phono stage (assuming it goes down that low) and you will probably see it along with some other scary looking stuff.

Dave, I was using my Acutex LPM320 (C = 42) in an FR64S, albeit with a lightweight headshell.  FR64S has M = 35 with its OEM headshell.  My headshell probably knocked 10g off that. But add back 6g for weight of the cartridge plus screws, for a calculated Fr = 4.4 Hz. Sounded fantastic until I pulled too hard on one of the Acutex leads and evidently disconnected the ground wire on one side.  (This is the cartridge I asked you if you wanted to fix.) Bass was flawless.

PS. I think you're probably right about what Korf meant.