Rasssspppy! Sounds like an old hen gargling with vinegar. When I made it, I just tuned it by sanding the soundboard side on my belt sander, then played with the striker stick until it sounded fairly good to me. Something I did to make it raspy was lightly score the striker at 90 degrees with a toothing plane iron, to make shallow scratches that the sound board would drag across. Plus with that rough finish it holds chalk better for me. There is also about an eighth inch radius on the striker, which seems to engage a smaller bit of the soundboard.