02:26Most bridges on acoustic fretted instruments are straight. Occasionally stringed instruments may have intonation problems as you go up the neck and play the lower strings.
There are various causes which contribute to intonation issues. The length-to-diameter ratio can play a part with these issues. A common explanation is that string gauge, or diameter, determines the amount of tension in the string when tuned to pitch and is a major culprit in intonation problems. If you look at the strings on most fretted instruments you will notice that they "fan out" slightly from the nut to the bridge. So, the slightly increased scale length of the "outside" strings also seems quite a plausible explanation as well.
Because the outer strings are slightly longer than the inner strings many fretted instruments may need to have the vibrating string length adjusted so they will play more correctly in tune. Frequently the bridge will be "compensated" by moving it or by cutting the saddle individually for each string to achieve the desired vibrating string length.
Because you can't move frets around as you play, the permanent placement of these individual string adjustments is crucial to the instrument playing in tune. Even minute adjustments to the compensation can make a noticeable difference in intonation.
In compensating a bridge, the luthier is also considering the fact that different strings stretch differently as they are pressed down to the frets. As they stretch, they become sharper in pitch, requiring that the vibrating length be adjusted accordingly.
The small amount of compensation needed varies with the string diameter and tuning. Players who play in unusual and "dropped" tunings may find they have greater need for compensation in those tunings. Some musicians have instruments set up with special compensation and use them for certain tunings only.
Not all fretted instruments will need any compensation. Mandolins, for example, are extremely sensitive to compensation because of their short string length.
Are compensation bridges right for every instrument? Probably not. A great deal depends on individual set-up adjustments and the construction of the instrument itself. There are plenty of fretted instruments that intonate just fine without the need for compensation.
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LAST UPDATED 05-05-2016 13:05