It struck me just the day before yesterday that all these years, while I have been talking about swapping plastic elements for a bone compensated saddle and nut, I have never really explained compensation, what it is, its importance; intonation, and what part a compensated saddle plays in intonation and all of that.
Before we launch into any of that let me put this out there that these are issues best left to experts – people who really know what they are doing – as opposed to music shop salespersons.
Simply put, compensation means that the saddle is placed at an angle to the strings rather than perpendicular to them, to give more length to the thicker (lower) strings and lesser for the thinner (high) ones.
Whenever a string is pressed to a fretboard, the tension in the string increases. This causes the fretted note to become sharp (slightly) compared to the open string note. This must be ‘compensated’ for. To compensate for this sharpness, the distance from the nut to the bridge saddle is made slightly longer than the stated scale length for the instrument. This lowers the pitch of the fretted notes slightly.
In an acoustic guitar, there are the many ifs and buts that must be factored in before we can say that a saddle is truly compensated. These include how far the string must be pressed to the fingerboard (action), the thickness (gauge) of the string, the tension (tightness) of the string, the scale length, and a person’s playing technique.
In the process of addressing a player’s particular playing style, a knowledgeable guitar technician will cut more accurate notches into the saddle, to properly ‘compensate’ each string. After the tech finishes working on the saddle, the top of it will have a shape akin to a lightning bolt.
Compensating notches on a saddle are generally seen where the e, B and G strings rest. This adjusts the length of the string ‘compensating’ for accurate ‘intonation’ so the guitar sounds in tune when notes are played down the fretboard (closer to the guitar body). The biggest culprit is the B string, which is quite a thick plain-steel string, and on a compensated saddle, it is given a bit more length compared to its neighbours (e and G strings).
A non-compensated saddle doesn’t have any grooves and is flat across the surface.
The guitar tech is then supposed to check the pitch of each string at the 12th fret (the halfway point of a string’s length) to ensure that it’s in tune with the pitch of the open string.
Intonation is the extent to which a particular note continues to remain in tune – down the fretboard – as opposed to sounding flat (lower) or sharp (higher). Usually, intonation issues are seen while playing down the fretboard.
The closer a string is to the frets, the less it needs to stretch since it doesn’t have far to go. This means that low action tends to produce more accurate intonation. And thus, intonation issues can be subtle or dramatic depending on a guitar’s set-up.
And that is why it is imperative to have a guitar set up by someone who knows what he/she is doing as opposed to someone who is just a salesman in a guitar store.
Did you know there are compensated nuts too?
At the nut, where the strings rest before being held by the tuning machines, a thorough inspection is critical. String slots that are not shaped properly, too shallow, or too deep, and the improper placement of the nut, will adversely affect intonation on an instrument.
So, when the compensation on the saddle is near perfect, and yet the intonation on the guitar is off, then compensation in the nut is dialled in. That generally happens because the construction of the guitar itself – the placement of the bridge on the top – is faulty.
The only way to tackle compensation at the nut is to throw the old nut and put in a fresh bone piece, which is then cut to the specific needs of that guitar. The comparative price of taking off the bridge and re-glueing it in the right place vis-a-vis making a compensated bone nut is more or less the same, BUT, a compensated nut is not so big an eyesore as a bridge that has been shifted from its original position. That can be seen from a mile off, unless you decide to refinish the top.
The photographs below show you (clockwise from left) a regular nut and the various modifications that can be made to nuts (compensation) to make the instrument play perfectly in tune.