updated 4/2016
Page Violin_91
Violin Neck tuning...side vibration...
...This concept came out of the study of wood grain orientation as it relates to the
wood of the violin neck structure.
.. As you may know that it is important to orientate the maple growth rings to be exactly horizontal. The sound is best conducted in the direction of the growth rings and that is why the growth rings are selected vertically on the top and back plates. The vibration of the plates is in the vertical direction (after the bridge turns the horizontal vibrations of the vibrating strings to vertical vibrations down through the bridge feet to the top place and thus to the back plate through the vertical sound post.
The neck, however, picks up horizontal vibrations from the vibrating strings, either through the stopped strings or through the nut during playing of open strings.
This horizontal vibration is thus best conducted to the body of the violin through horizontal orientation of the grain of the neck as well as through the horizontal grain orientation of both the fingerboard and tailpiece (how to discover the grain orientation of pitch black ebony wood is a different subject!).
The vibrating string (through the action of the bow) sets up vibrations that travel to both ends of the string. The bridge effectively turns the vibrations it feels to plate motion, which in turn sends sound waves out to our listeners.
However, at the other end of the violin, those vibrations are also important to be captured and then also transmitted to the violin sound box, to be added to the overall sound produced.
After much study in other areas of violin sound productioin, this area is now studied and I believe that this tap tone frequency should also be a specific frequency: 198HZ, the same tap tone frequency as the back plate (G below middle C)
,,,The adjustment is simple, fast, and really makes a difference in playing performance if it is either too high or too low; or uneven side to side. The side tap tone at the junction of the nut, fingerboard, and maple neck wood; is tapped directly in from the side. Both sides of the neck need to match.
...If the side tap is too low, then wood needs to be removed from the inside back surface of the peg box (the end toward the fingerboard). Remove more wood from the lowest side until both match in tap tone and then raise them evenly until the 198HZ tap tone goal is realized. (please see photos and video instructional file for details).
..Please let me know what you discover with your own instrument.
...Tap here (from both sides) directly from the side to hear the neck side tap tone for the instrument.. We want this to be 198HZ the same as the center of the back plate.
..Wood is removed from this back surface of the peg box to adjust the neck side tap tone.
..If the side tap is too low (below 198HZ) we remove some wood evenly from this surface until the tap tone frequency is correct. If it is lower on one side of the neck than the other, then remove more wood from that side to even the two tap tones out.
..If however, the tap tone is too high, then shape and glue in a piece of matching maple wood until the side tap is then too low. Carve this new surface to raise back to the ideal 198HZ.
..See a companion video instruction 
of this acoustical tap tone adjustment 
by clicking here...