Impact of aging or playing in on fequency response

[Dominic]

Hi Trevor, apologies if I have missed this in your book somewhere but what is the impact of aging or playing in of a guitar on its frequency response? Do the peak frequencies move or are we hearing something else develop as a guitar plays in?
Is this something you keep in mind when building a guitar?
Cheers
Dominic

[Trevor Gore]

Dominic, There's nothing significant in the book on ageing or playing in, mainly because I have nothing systematic and scientific that I can report. Sure, guitars change over time and even seem to change from day to day (which is as likely to be psychoacoustic as much as the guitar). My own experience is that after a short period of stabilisation the mode frequencies of my guitars don't change very much and that guitars I've built seem to get a little louder sounding with age, but otherwise sound much the same. Other builders have said very different things about their guitars. But I've also measured the mode frequencies of quite a few master built Spanish guitars from the 70's and 80's which have mode frequencies on or very close to 190Hz, which seems too tight a spread to be coincidental. So they seem to have stayed quite stable for 40-odd years.

The side mass concept allows the T(1,1)2 mode frequency (main top mode) to been tuned just by changing the masses, so this is a great way to keep an instrument "on song" without having to mess with the woodwork.

Rgds, Trevor.