My JTV-69 has exactly the same issue with F# resonance on the J200 model (which is my preferred acoustic model). It actually starts to resonate somewhat on either side of F#. Just as previously described it happens on the D string 4th fret, A string 9th fret, and E string 14th fret. I believe technically it's F#3, which is at185 Hz. It plays much louder than the surrounding notes. Also as described above, it moves frets when the pitch is changed by a 1/2 step or whole step. I play through FRFR speakers or headphones, and it happens on both. My guitar is also Korean, although I don't think that's an issue. It plays fine everywhere else - no real plinking issues, buzz, etc. Other than this issue, I really enjoy the guitar. The acoustic modeling has been frustrating and disappointing though - and it was one of the major reasons I bought the Variax. I've been trying to EQ the resonance out, but I'm still trying to get a grip on how the Parametic EQ on my Pod HD500X works. rdeshenbaugh would you mind sharing your parametric settings?