Intonation

It’s not rocket science guys. I recently bought a guitar that is simply stunning, but the intonation was way out. Consequently, it sounded out of tune.

The theory is, that any string that is in tune (open), is also in tune at the 12th and 24th fret. There is one variable that will always defeat this – the amount of pressure you put on the string while fretting it. In theory, the 12th fret is exactly half way between the bridge and the nut. We’ll asume for a moment that you have already set your action, the nut is cut properly and the bridge is in good condition. The reason that the 12th fret is not exactly at the centre point is that when you fret a string, you are bending it until it touches the frets. for this reason, the distance between the nut and the 12th fret is always just a little less than the distance between the 12th fret and the bridge.

I’ve never had any real problem with intonation, I set it when I buy a guitar, and that’s pretty much the last time I ever need to consider it. Part of the reason for this is that my action, neck straightness, string guages, etc. remain constant as does the amount of pressure I use when fretting a string.

You will notice that on most instruments, the saddle of the E (6th) string is further back than the A and D, , and that the pattern almost repeats with the G, B, and E(1st) is further forward. To adjust the intonation, use your guitar tuner. With the instrument in tune, check tuning at the 12th fret. If the 12th fret is sharp, move the saddle back and retune. If it’s flat, move the saddle forward and retune. Then repeat the process until all strings are in tune both open, and at the 12th fret. Normally, this will only take you a few minutes and your guitar will sound much better after it’s done.

Here are some pictures. All of these intonations are correct, even if they all look different. Click on the pictures below to see in more detail.