Why do instruments need periodic adjustment? Jun/Jul 2004
Instruments’ playability and tone depend on many parts functioning as a system. If any one part fails to perform properly, the system cannot work perfectly. The cumulative effects of time, string tension and vibration, damage incurred from inappropriate tuning and care, amateur adjustments to the instrument and seasonal variations in temperature and humidity all contribute to the need for periodic skilled adjustments to stringed instruments.
Over time, string tension & vibration promote settling of the angle of the neck relative to the body of the instrument. This change affects playability & tone. As the angle decreases, the strings rise higher off of the fingerboard & the instrument becomes difficult to play. When strings are higher than they should be, the instrument will play sharp, even near the nut, worse in higher positions.
Almost all new instruments shift during the first several months of being played. The newly assembled joints ‘settle in’ as they vibrate under tension. For this reason, new instruments need adjustment in 6 months to a year of play time. In general, the adjustment is small & easy for a qualified technician to perform. We do not recommend do-it-yourself adjustments for reasons we explain more fully below.
Older instruments continue to shift with time. But, well-made instruments shift more slowly after the initial ‘settle in.’ Small adjustments maintain the playability & tone. Eventually, adjustment will require modification of the bridge (violins, banjos, mandolins) or saddle (guitars). Lowering the bridge/saddle lowers the action & restores playability & intonation. Because this modification also slightly reduces the instrument’s volume, repair technicians defer this step as long as possible. But they will lower a bridge/saddle before they perform the last, most drastic adjustment -- neck reset.
Inappropriate tuning & neglect accelerate the process that makes adjustment necessary. Higher-than-st&ard tuning & heavier-than-recommended string gauge increase the tension that the instrument experiences. High temperature softens the glue that holds the neck to the body. Both of these things promote neck rotation & accelerate the need for adjustment. Similarly, poorly executed amateur adjustments can cause problems in otherwise sound instruments & aggravate problems that an experienced repair technician could easily remedy.
Seasonal variations in temperature & humidity also drive the need for periodic adjustment. Low temperature & humidity tend to lower action; warm temperature & high humidity tend to raise action. These changes are cyclic & reversible, but can cause playability & tonal issues that players want corrected. Adjustments for seasonal shifts are generally minimal & non-invasive.
Many musicians perform adjustments to the truss rod in their instruments’ necks, to the bridge & saddle, to the nut, frets, tailpiece & sound post. Certainly, anyone can study authoritative sources of information for instrument set-up & become qualified to make these adjustments. The key words are ‘study’ & ‘become qualified.’ The ways in which instruments’ parts work together is not so complex that an intelligent person cannot understand it, but the relationships are not so simple that the interaction is ‘obvious.’ A partial turn of the truss rod, minute changes to the height or position of the saddle - these adjustments can have large effects.
What can I do?
We recommend that you have these adjustments made regularly to keep your instrument in ideal condition. But, since some of the changes can be damaging & irreversible, we recommend that the person who does them should study & become qualified BEFORE doing them.