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I keep hearing about tops dropping in freq as they 'open up'.
I've been tracking the freqs (loosely) of a few of my guitars and have not noticed any discernible change over time.
Is anyone here collecting data like that? Just want to know if it's a predictable phenomenon to be accounted for during building...

Thanks

I've only got long term data on a few guitars (most of mine I rarely see once they've gone). There seems to be no systematic change over ~10 years on the guitars I've got history for. The most rapid movement is in the first few days of new guitars as things settle and whilst you're still tweaking things. The data I have includes some factory built, standard X-braced guitars, too.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Glad to hear.
It would be unfortunate to carefully pitch your plates only to have them drop freqs over time...

...can always re-tune if required just by altering the side masses (bolt in, bolt out).

_________________
Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Seems like another +1 for your method. But with the cf you use, change seems less likely than on a normal guitar...

Likely true. The sample also contains a conventional X-braced guitar, no CF, factory built in 1992. T(1,1)2 of 174Hz then, same yesterday. So that one has gone nowhere, either. In the book I report on a number of Spanish classicals with T(1,1)2's all at 190Hz or very close, which seems too much of a coincidence to be random. They were mostly 70's guitars, but well preserved, and my guess is they were built with tops at that frequency, though, of course, that's impossible to prove. So there's at least some evidence to suggest that well made guitars can hang in there for 20-40 years.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

This is good, thanks...

Denis Merrill is. Run a google on the Sonic Sitka project. The notion here was to give Sitka tops to about 100 builders, have them do their thing (no limits in terms of design or style) and sonically test the guitars over time. (at this point most of the guitars are only about 3 years old, so early yet by any measure.) I was fortunate enough to be one of the 100. Denis has run at least one round of testing on the guitars, so the jury's out in terms of quantifiable data as of yet. I'm sure if you dropped Denis a line he'd give you his perspective.