Thanks for the replies, folks. Sorry for not joining back into the conversation sooner. After the post immediately following my OP, I got a bit turned off and thought I'd focus on other things for awhile.
Ripster, when I went to Brian at EK with the ping issue, he was very forthcoming and gracious about it. He told me that he rarely finds one of the Leopolds that don't have at least "a few" keys or at least "a small area" of the board that will ping at least a little.
He explained to me that it's a design defect of the switches -- and that it's an entirely random, intermittent phenomenon where most switches don't exhibit the issue but a reasonable h percentage do. He pointed out that he boards exacerbate the pinging sound that the switches generate. That has been exactly my limited experience.
Then, well, gee… I really don't remember. He may have offered to send me a temporary replacement board at no charge so I could pick which of the two I preferred. Or I may have volunteered to just buy a second one and keep both, and use the second-choice one at home.
By the way, that experience led me to asking myself, gee… what's proper protocol if you develop a good rapport with a manufacturer and he does you a little favor? Do you tell others so they know how good of a man he is, or do you keep it close to the vest so others aren't expecting favors from him all the time?
And somehow I don’t remember what happened. Isn’t that peculiar?
I can tell you that I ended up trying two Leopolds and they both had pinging, in different ways and different places (though in both cases in was in the right half of the board).
Brian at EK told me that after my having tried two, it probably was a waste of time to try more because it was very unlikely I'd find one that didn't exhibit the issue.
That was back in September. I still have no idea what the “improved” Leopolds are that I think I read something about.
That was my experience with two Leopolds – full-sized.
I can definitely say that the board I got briefly from Weyman at WASD, before returning it right away (he, too, was extremely gracious in all ways), did not exhibit remotely the same kind of pinging as the Leopolds. It was very different.
With the Leopolds, much of the board just felt solid and neither the switches nor the base exhibited any noise at all -- but some switches would really trigger the ringing, and the base would then amplify it nicely.
In the case of the WASD, though, none of the switches made any particularly noticeable pinging noise (it was Browns, just like with my Leopold), but instead the entire board, or base rather, uniformly exhibited a low-level but consistently noticeable dull ringing that I would probably have noticed enough to have found always a bit annoying. But it’s possible I wouldn’t have noticed any noise at all during normal daily work.
It's because of how very differently those two makes of boards seems to be made and to exhibit a pinging that I ended up thinking that maybe a Filco “might” be better, maybe the best of both worlds.
As far as a mod goes, I have almost, sorta come up with a reasonably effective solution, I think... almost.
What I found was that, at least with the Leopold (which I can experiment with since I own that one), if I just laid the keyboard flat, without extending the feet, it reduced the sound considerably. This led me to trying something further, or at least "wanting" to try something further.
It seems to me that it would be really effective if one were to get a few sheets of, say, 1/8" thick rubber, which my local hardware store sells as gasket material, cut them to the size of the keyboard and put them under the keyboard so the base of the keyboard lays right on the rubber and not on the feet – either because of cutting the rubber sheet shy of the feet and layering the rubber sheets it so they’re thicker than the keyboard’s feet, or by just removing the rubber feet that the keyboard came with.
This, of course, means the keyboard is not elevated at the back, which so many people prefer.
But it should be able to dramatically if not entirely eliminate any audible ringing noise. And it even would provide a really solid feel to the keyboard, which I happen to like a lot.
The problem I encountered, though, is that the Leopold is far from flat! It's got so much of a “bend” to it that if I place it on rubber sheet that way that's the full size of the keyboard, the keyboard "rocks" from side to side and is only making solid contact in the middle.! So, I never got to actually try my theory.
Of course, the Leopold not being perfectly flat is never, ever, ever an issue if you just use its four feet.
If a layer of rubber works as expected, and one does want the back of the keyboard elevated, then the next best thing would be a strip of rubber under the front of the keyboard and about half-a-dozen strips stacked up across the back end of the keyboard. It would result in an “angled” keyboard laying on a “flat” surface at the back end and therefore would not provide the same amount of solid surface contact as when the keyboard is actually flat on rubber sheet, but it should do a pretty good job anyway. It would be far more solid support than just the four feet that are provided that come with a keyboard, and it should reduce vibration/ringing substantially.)
I'm actually looking forward to trying something like that. But, uh, does anyone know if the Filco, or Topre, will be flat or close to it?
That’s assuming they even need any sound dampening.
Naturally, another possible solution would be a wedge of rubber, so the keyboard is fully supported and yet is elevated at the back. (That would also provide a really solid feel, and surely prevent any walking.) Two sizes might fit all or most.
Of course, if the keyboard is just not really flat in the first place, I don’t have a solution for that.
I have to say, with all the discussion amongst enthusiasts about this issue, I’m surprised we aren’t seeing just that – rubber wedges to support the entire bottom surface of the keyboard.
EDIT: I turns out that I ended up liking and keeping the WASD. See further explanation in post #30 of this thread.