“My guitar has a few notes that buzz. I have taken it to good guitar techs before and it plays great for a while, but eventually starts buzzing again. This time I was thinking I could make some adjustments myself, but when I raise the string height so they don’t buzz the action is too high. What does a guitar tech do to stop fret buzz without raising the action?”
They keep asking us for these trade secrets, as if we’re just going to tell them. Yeah, right! But seriously folks, it takes years of experience to become a really competent guitar technician. Just like mixing, mastering, and many other things we’ve discussed in inSync there is no simple, one paragraph answer that will suddenly turn you into an expert.
However you may want to consider making a neck tension or truss rod adjustment. The truss rod of most guitars can be accessed from an opening at one end of the neck. Some have it up at the headstock and others have it down where the neck enters the body. Quite often it will be covered by a piece of plastic that can be easily removed for access.
The neck of your guitar or bass should have some ‘bow’ in it. In other words it really shouldn’t be perfectly straight. Fret buzz is generally caused by some combination of not enough bow in the neck, the bridge string height being set too low, and possibly a warped or irregular neck. Other important concerns are consistent fret height over the length of the neck and the type and thickness of strings used. ALWAYS set your guitar up with the exact brand and type of strings you use installed, and then continue to use exactly those.
To check the amount of bow in a neck many people look down the length of it and basically eyeball it. There is a slightly more scientific way to do this without any special equipment. Fret your low E string (the big one) at the first fret and at the highest fret (this will obviously require two hands). Look down on the neck from above (like if you were playing) and observe the height relationship of the string with the neck and frets. When the string is held against the highest and lowest fret there should be a gap between the 12th fret and the string. If they are touching or too close to each other you probably need to put more bow in your neck to prevent fret buzz from occurring somewhere on the fingerboard. If they are too far apart you may want less bow in your neck to make it easier to play. These are truss rod adjustments. Turn it about an eighth or quarter of a turn at a time and observe what happens to this string/fret relationship. This technique is useful because it eliminates the bridge and nut (the overall string height, or action) from the equation and lets you look only at the shape of the neck. Personal preferences will differ, but most players prefer this gap at the 12th fret to be between 1/32 and 1/8 of an inch, sometimes more for bass. It also depends on the thickness of the strings and the height of the strings as determined by the bridge. There are many variables that interact with one another, which is why good guitar techs are well worth the money.