Adjustable Neck

   
     

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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 stringís 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. Thatís it! Thereís 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 Iím 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 donít 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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