Overtone on Takamine Santa Fe

[foxyloxy]

Hi, I recently bought a nice used Tak. Santa Fe with great sustain, but when I play a G chord on open strings - just the D,G and B strings - I get a fairly loud F# overtone. Now I realise F# is an overtone for D - I'm just curious why this overtone is so loud - I am a bit deaf, so it's possible that there are higher overtones that I can't hear. Would it be usual for the lowest overtone to be loudest ? I can hear higher overtones played on the 5th, 7th and 12th frets. Would appreciate any helpful comments.