I have a 3-month-old set of Obligatos on a carved Juzek, whose previous owneran orchestral player--had Kolstein do the set-up 10 years ago. The bass play well; all the open strings ring and resonate well and evenly when pizzed lightly or forcefully, and bow evenly and openly as well. Playing pizzacato, when I note along the G, A and E strings, I get a pleasing sound on all notes, one that resonates openly, even growls a bit, especially if I add a little vibrato. The sound seems to be open, with lots of overtones and depth. The strings sing. As I play the D string, however, noting from 1st position upwards, the quality of the sound changes. If I pizz lightly, the D resonates with that same growl tone as the G, A and E strings when they are played with the same moderate force, but the growl on the D has a fraction less sustain and volume. But as soon as I start to pull hard across the noted D string, the sound chokes up and sounds thunky, losing its growl and overtones and seeming to be a fundamental tone only, even though the other strings continue to respond well in noted positions when pulled harder. The D string also suffers from a rather severe wolftone at the A-flat/A frets. I have a wolftone eliminator on the A string, which substantially mitigates the A-flat/A wolf in pizzacato on that string, and makes it very manageable in arco But the wolftone of the D string at the noted A-flat/A is quite noticeable in arco and in the pizz mode as well, where it sounds thunky, lacking resonance and overtones. Any thoughts on what might be causing the thunkiness and flat sound on the D string when its noted? Bad string? Fingerboard? Wolftone? Soundpost? Poor technique? Id appreciate any insights into this. Thanks.