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The James Ham
adjustable neck, introduced in June 1995, is the result of my experience
with the conflicting needs of fine bass players to have on one hand the
ultimate in sound, sensitivity and responsiveness from their instrument,
and on the other the ability to adjust the string’s distance from the
fingerboard to compensate for changes due to humidity variations and for
different playing needs. To use it, the player simply inserts a key
(either the fancy one provided with the instrument which matches the
tuning keys or an ordinary 3/16 hex key) and turns it to move the neck
as close to or far from the string as desired. That’s it! There’s no
need to reduce string tension or even retune! Why not? When the neck
moves, it slides on a surface which is designed to have a right angle
relationship with the string. This means that as the neck moves, the
string length (and therefore tension) change is extremely small-so small
that there is no discernible change in pitch. This makes for convenient
action adjustments but is there a sacrifice in sound? Not at all! In
fact I have designed the adjustment mechanism to insure that the neck is
stronger and more secure in the neck root area than a traditional neck
due to the deeper tenon extending into the upper block and to the
titanium rod within the tenon both of which greatly strengthen what has
been a weak spot in the traditional design. Further, by moving the
adjustment function away from the most acoustically sensitive part of
the instrument (the bridge) to the least sensitive (the upper block),
there is no need to compromise the acoustic quality of the bridge with
the added mass and reduced vibrating resilience caused by cutting off
the legs and adding bridge adjusters.
You may have seen pictures of earlier
versions of my adjustable neck in The Double Bassist, The Strad or ISB
Bassworld articles. I have updated and improved some of the components
since then but the basic principles remain the same, in fact the new
parts can be retrofitted to earlier Ham basses. As always, whenever I
make an instrument I’m keeping the future repairabilty of the instrument
in mind and the adjustable neck design has advantages for the repairman
as well as the player. As seen in the photos, the neck can be removed
from the instrument in a few minutes! There is a separate piece of maple
glued to the upper block where the neck tenon is. This gives extra
support to the neck root and reduces the surface where the spruce top
glues at the block to about the same width as the gluing surface around
the ribs. As a result, if the top ever needs to be removed for repairs,
the neck can first be removed and then the top can be removed without
need to disturb the neck junction area. The neck can also be removed
from the bass by the player for shipping or transportation but as with
any fine instrument, the sound will not be at its best until the strings
have been on for a while, and of course there is the possibility of the
sound post falling over. For these reasons I don’t promote the idea of
removing the neck for travel although it is certainly possible. Above are
a few pictures of the adjustable neck on the finished bass and a peek at
the parts inside on basses under construction.
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